hoods handbook
Checklist
for Selecting and Planning
a Cooker Hood
Cooker Hoods
A Handbook for Planning and Selection
www.electrolux.com
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Cover; Size: 160 x 270 mm;
Material: 250gsm Claro silk
CHECKLIST
CHECKLIST
Checklist
6. Extraction or recirculation?
What you need to consider when selecting
and planning a cooker hood.
Island hood
Chimney hood
Designer wall hood
Ceiling extractor
Flat screen hood
–
–
–
–
t check: Is extraction possible?
– Is extractor ducting possible?
7. For recirculating hoods
1. Select the required appliance design:
–
–
–
–
–
– Energy-efficient house
Retractable table-top hood
Extractor module
Built-in hood
Conventional hood
– Active carbon filter required
– Regenerative active carbon filter desired?
8. For extraction hoods
– Are there any ambient air heating appliances?
2. Calculate the required airflow rate/extraction performance
Extraction performance = room volume x 12 (maximum ventilation rate)
3. What hob type is the cooker hood needed for?
Electric or gas hob?
– Observe the installation height/safety distance specified by the manufacturer
– Width of the cooker hood?
t At least the same width as the hob, but wider is better
t Edge extraction is recommended if the cooker hood is the same
width as the hob
t Ensure sufficient intake air
t Window contact switch
– Planning the extractor ducting
t Via a wall vent?
* Observe local building codes and neighbours’ rights regarding
installation of wall vents
* Is there a wall vent?
Is the diameter sufficient?
*
Selecting the wall vent:
-
Exhaust air wall vent
-
Exhaust and intake air wall vent
t Via a chimney? Observe legal regulations!
4. Cooker hood noise level?
t Via a roof outlet? Condensation trap required?
t Exhaust air ducting:
5. Cooker hood features and user-friendliness
Published by:
– Control elements:
Company name and address to be update locally.
Responsible for the content:
to be update locally
1st Edition 2013
Reproduction and photocopying of this text, including extracts thereof,
is only permissible with the publisher's consent.
No liability is accepted for the correctness of technical details or for
any errors occurring during compilation or printing.
BMEECH13LL146002_Cover.indd 4-6
– Features:
t
t
t
t
Buttons
Touch operation
Hob-based controls
Remote control
t
t
t
t
t
Lighting (LED, halogen etc.)
Saturation indicator
Power regulation sensor
Fan run-on
*
Material
*
Shape
*
Diameter: at least 125 mm
*
Length of ducting
*
Number of bends
t Planning the air intake
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Cover; Size: 160 x 270 mm;
Material: 250gsm Claro silk
INTRODUCTION
What is the purpose
of this handbook?
Cooker hoods should look good in the new kitchen, light up the hob and of course
remove cooking vapours. However, the latter, the actual purpose of a cooker hood,
often plays a less important role in the selection process.
Certain basic principles need to be understood and observed during the selection
and planning process to ensure the extraction system works effectively.
This handbook provides you with:
– Background information on planning, including technical aspects of ventilation
– "At a glance" – summary of information and overviews
We would like to thank:
– Naber of Nordhorn who provided us with information on ventilation technology
and extraction ducting
– The Institute for Household Technology and Ecotrophology in Kranzberg for its
support in creating this text.
We wish you successful planning
Electrolux
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160 x 270 mm; Pages: 90
Material: 250gsm Claro silk
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CONTENTS
CONTENTS
Contents
Basic principles of ventilation technology
and cooker hoods
06
Appliance selection
62
Need of a cooker hood in the kitchen.
Ventilation systems
Room climate
09
10
11
Operating modes.
Extraction or recirculation
15
16
Ventilation performance.
Calculating the theoretically required ventilation performance
19
20
65
66
67
67
68
70
73
75
75
Basics – at a glance
22
The technology of cooker hoods.
Design of a cooker hood
Centrifugal fan
Inverter motor
Surface extraction and edge extraction
Grease filter
Odour filter - active carbon filter
Lighting
Operation
Ventilation performance/airflow rate in accordance
with IEC 61591/EN60704-3
Noise levels
Planning
24
Designs of cooker hoods.
Island hoods
Chimney hoods
Wall hoods
Ceiling extractors
Worktop extractors/hob extractors
Retractable table-top hoods
Extractor modules
Built-in hoods
Conventional hoods
79
80
80
81
82
82
83
83
84
85
Appliance selection – at a glance
86
Index
88
Choosing the right cooker hood.
Width of the cooker hood
Installation height/safety distances
Information on woks, deep fat fryers, grill pans and similar
Information on large gas hobs
27
28
29
30
31
Recommended operating mode.
Important aspects of extraction or recirculation hoods
Energy-efficient houses
33
34
35
Important aspects of planning exhaust air ducting
Characteristic curves of a cooker hood
Information on exhaust air ducting
39
40
42
Why does exhaust air need intake air?
Exhaust air needs intake air
53
54
Legal requirements concerning exhaust
air and intake air ducting.
Expelling exhaust air through chimneys
Ambient air heating appliances
Legal regulations for the installation of wall vents
57
58
59
60
Planning – at a glance
61
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76
77
You can find a check-list at the centre of this brochure from page 40.
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Basic principles
of ventilation &
cooker hoods
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BASIC PRINCIPLES
Need of a cooker
hood in the
kitchen
The moisture and odours released during
cooking pose a challenge with regard to
ventilation and hygiene in the kitchen.
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BASIC PRINCIPLES Ventilation systems
Room climate BASIC PRINCIPLES
Ventilation systems
Rooms can be ventilated naturally by
opening windows and doors or
electrically using motorised appliances
such as cooker hoods. A high level of
air exchange is particularly necessary in
kitchens as an increased level of fumes
and steam is released while cooking.
Using open windows as a means of
ventilation and extraction tends to
provide unreliable result as the level of
ventilation is dependent on temperature
and wind conditions. The greater the
temperature difference between
indoors and outdoors, the larger the
lifting force and the greater the
exchange of air. The exchange of air
can be increased by strong wind or by
opening additional windows or doors
(creating draughts). This uncontrolled
exchange of air does, however, result in
the loss of energy and heat. Moreover,
using windows as a means of
ventilation does little to remove grease
particles.
The only way to ensure proper
ventilation and extraction in a kitchen is
to properly control the exchange of air.
Cooker hoods driven by electric motors
are therefore used to ventilate and
extract air from kitchens. Cooker hoods
speed up the exchange of air within the
kitchen, filter out grease particles and
neutralise odours. When operating in
extraction mode, they also convey
moisture outside of the kitchen.
Room climate
In addition to a mixture of moisture,
grease and odorants, which are
collectively referred to as vapour,
cooking also generates heat and dust.
All of these factors have various
negative effects on the air, environment
and furnishings.
Moisture
A large amount of water is used when
cooking food such as rice, pasta or
soup on the hob. Water boils at a
temperature of approx. 100 °C and
then releases a large amount of steam.
This releases approximately 1.5 litres of
moisture into the kitchen over the
course of a day. Once the air in the
room is saturated with water vapour,
the steam condenses on walls,
windows and furniture. If this moisture
remains in the room, it can lead to
excess humidity and therefore to the
formation of mould, structural damage
and swollen, distorted wood (kitchen
fittings), as well as creating an
unpleasant and unhealthy room climate.
order to promote a pleasant room
climate and prevent the formation of
mould. Excess moisture can only be
removed through adequate and correct
ventilation. To this end, it is important
that the moisture is removed at the
point and time of origin. Preferably
through a cooker hood in extraction
mode (if permissible; see chapter on
"Energy-efficient houses", page 29), a
permanent ventilation system or
intensive airing after cooking.
Most people find a relative
atmospheric humidity of between
40% and 60% to be pleasant. The
level at which the air feels “too dry”
or “too humid” is also determined by
the room temperature. The following
diagram shows the comfortable
range.
In energy-efficient houses, it is
particularly important to provide an
efficient means of removing moisture in
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BASIC PRINCIPLES Room climate
Room climate BASIC PRINCIPLES
Solids
In the kitchen, dust particles are
primarily created when baking. Flour,
icing sugar and cocoa powder are
particularly problematic. Household
dust and candles that emit soot can
also be a nuisance. Solids that combine
with vapour in the air and condense
onto walls and fittings can give rise to
large accumulations of dirt. This results
in a need for time-consuming cleaning
activities. People with allergies also tend
to suffer more from the unclean air in
the room.
COMFORT CURVE
100
Relative room air
humidity µ (%)
90
Uncomfortably
humid
80
70
60
COMFORTABLE
50
40
30
JUST COMFORTABLE
20
10
0
Uncomfortably dry
14
16
18
20
22
Grease
When cooking with fat or oil, small
particles of grease are released into
the air and create a thin film on fittings,
appliances and walls. These grease
deposits not only trap dirt but also pose
a hygiene risk as they provide perfect
breeding grounds for bacteria. This
results in a need for time-consuming
cleaning activities.
Odors
Cooking usually releases pleasant and
appetising aromas. Once cooled down,
however, these aromas tend to become
unpleasant. The spread of odours to
neighbouring rooms (living room,
bedroom) is usually undesirable. If the
odorous substances are not expelled
from the house or filtered from the air,
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24
26
28
Room air
temperature (°C)
they can become trapped in many
areas (particularly in textiles) and emit
unpleasant odours throughout the
entire room.
Heat
Most people find a room temperature
of between 18 and 23 °C to be
pleasant. If the temperature in the
kitchen rises due to the heat generated
by household appliances (oven, hob,
refrigerators), it quickly becomes
unpleasant – especially when
compounded by humidity. These
conditions also provide an ideal
environment for bacteria and mould.
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BASIC PRINCIPLES
Operating modes
A cooker hood sucks in the vapours from the hob,
filters them and releases the filtered air either to
the outside (extraction mode) or back into the
kitchen (recirculation mode). While extraction
mode is more effective, the choice of operating
mode depends on many factors.
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BASIC PRINCIPLES Operating modes
Operating modes BASIC PRINCIPLES
Extraction or recirculation
Extraction
In extraction mode, cooker hoods use a
fan to suck in vapours, pass the vapours
through a grease filter made from metal
(permanent filter) or fleece (disposable
Benefits:
– High airflow rate
– Excess moisture is conveyed
outdoors
– High effectiveness at low hood
settings
– No regular replacement costs for
metal filters
– Usually quieter than recirculating
hoods if exhaust ducts are laid
properly
– No additional costs for active
carbon filters
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filter) to remove the grease for hygiene
reasons and blow the filtered air outdoors.
By removing all the vapours generated,
this system also diverts excess moisture,
heat and odorous substances outdoors.
The fan is usually located inside the
cooker hood. Models with an external fan
attached to the outside wall, for instance,
are also available.
The filtered air is conveyed from the room
to the outside via exhaust ducts and a
wall vent or via the roof. Fresh air must be
supplied at the same time to prevent the
formation of negative pressure. In other
words: Exhaust air needs intake air. (See
page 32 and page 46)
Note:
– Structural factors may prevent use
in some situations (need to break
through a wall, lay an air duct)
– Energy loss through heat extraction
– Optimal exhaust air routing
required for high airflow volumes
– Legal regulations (e.g. German
Ordinance on Combustion
Equipment [FeuVO]) need to be
observed
Recirculation mode
In recirculation mode, cooker hoods
use a fan to suck in vapours, pass the
vapours through a grease filter made
from metal (permanent filter) or fleece
(disposable filter) to remove the grease
for hygiene reasons and then absorb
the odours using an integrated active
carbon filter. The cleaned air is then
conveyed back into the room.
Recirculation mode involves a closed
circuit as there is no exchange with the
outdoor air. This prevents the loss of
heat. It is, however, important to
ventilate the room after cooking
(intensive airing) or, where available, to
leave the controlled domestic ventilation
system running to remove excess
moisture. The cooker hood should also
be left running for around 20 min after
cooking to remove any odours present
and dry out the odour filter.
Recirculating hoods are used in
kitchens and houses where it is not
possible to convey the air outdoors for
structural reasons.
TIP
Unless wall units are to be installed
directly adjacent to the cooker hood, it
is advisable to leave an adequate
distance between the cooker hood and
walls or kitchen cupboards when
planning a recirculation hood. This will
reduce the amount of turbulence. A
distance of approximately 2 metres
(from chimney to wall) can be used as a
guide value. The more powerful the
ventilation, the greater the distance
should be.
Benefits:
– Easy installation
– No additional structural work
required (no need to break through
walls)
– Hardly any loss of energy due to
the discharge of warm indoor air
through the cooker hood over a
long period of time
Note:
– Moisture must be removed through
additional intensive airing (leading
to a loss of heat)
– Active carbon filter requires regular
cleaning/replacement
– Relatively high running costs due to
filter replacements
– Usually louder than an extraction
hood (depending on the routing of
air)
– Airflow rate is reduced by the active
carbon filter
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BASIC PRINCIPLES
Ventilation
performance
Cooker hoods have different performance
capacities. A simple formula can be used
to aid selection.
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BASIC PRINCIPLES Calculation of ventilation performance
Calculating the theoretically
required ventilation
performance
Ventilation performance (airflow rate)
indicates how many cubic metres of air
the cooker hood will displace per hour. It
is expressed as m³/h. The required
ventilation performance is determined
primarily by the room volume (floor area
x room height) and the required air
exchange rate.
Ventilation performance is
calculated as follows:
Q = Vxf
Q = Required ventilation performance
V = Room volume
f = Air exchange rate
Kitchen fittings equate to around 20% of
the calculated room volume. This can be
either deducted from the room volume
or retained as a performance reserve to
compensate for any losses, for instance
through active carbon filters.
According to current understanding,
when performing the calculation for an
open-plan living/kitchen area, only the
effective kitchen surface area (without
any deductions) needs to be used as the
basis for the calculation — not the entire
living area.
The air exchange rate describes how
often the entire volume of air in the room
needs to be recirculated or replaced
each hour. Note that the air needs to be
recirculated more frequently in smaller
rooms than in larger rooms. The lower
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volume of air in smaller rooms means
that the vapour content in the room air
increases relatively quickly, which results
in the air becoming saturated more
quickly and increases the need for more
frequent recirculation or replacement.
To ensure optimal air purification, the
hood used should exchange the air in
the room 6 to 12 times per hour. This
rate of air exchange is still low enough to
prevent the formation of draughts.
The required airflow rate is calculated for
both minimum performance (for instance
when simmering vegetables) and
maximum performance (for instance
when frying with lots of oil or fat). To do
this, multiply the room volume once by
the lowest air exchange rate (f = 6) and
once by the highest air exchange rate (f
= 12). You can then use this pair of
values to identify a suitable appliance or
performance level.
Calculation of ventilation performance BASIC PRINCIPLES
Example calculations
Required ventilation
performance
Small kitchen
Large kitchen
Area x height = Room volume
10 m² x 2.5 m = 25 m³ 16 m² x 2.5 m = 40 m³
To replace the air 6 times each
hour, the minimum performance
(e.g. for simmering) is
150 m³/h
240 m³/h
To replace the air 12 times each hour,
the maximum performance (e.g. for 300 m³/h
searing) is
480 m³/h
Ventilation performance
HEIGHT
SURFACE AREA
DE
PTH
H
DT
WI
TIP
The calculation of the theoretically
required airflow rate does not take into
account any losses caused by the
exhaust ducting. Depending on the
design of the exhaust ducting (length
and cross section, surface quality,
bends), the theoretically required airflow
rate is reduced to an effective/actual rate.
Any cross-flow of air in the room will also
affect the effective extraction of vapours.
(See chapter "Why does exhaust air
need intake air?", page 46)
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BASIC PRINCIPLES At a glance
AT A GLANCE
– Cooking generates vapours
containing grease, moisture and
odours that condense on surfaces
in the kitchen.
– In extraction mode, the air is
expelled to the outside to effectively
remove humidity and odours.
– A cooker hood enables controlled
air exchange.
– In recirculation mode, the filtered air
is fed back into the room. Humidity
must be removed through additional
intensive airing.
– The required ventilation
performance of a cooker hood is
calculated as follows: Ventilation
performance = Room volume x air
exchange per hour (max. 12 times)
– Grease is removed from the
vapours by disposable filters or
washable metal filters.
– Extraction and recirculation modes
are available.
– Active carbon filters in recirculating
hoods bind cooking odours. These
must be replaced on a regular
basis; some of them are washable.
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Planning
24
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PLANNING
Choosing the
right cooker
hood
Various aspects need to be considered during
the planning phase to ensure the cooker hood
can be used to its full effect.
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PLANNING Width of the cooker hood
Installation height/safety distances PLANNING
Width of the cooker hood
The movement of air in the kitchen
(cross-flow) causes the vapours created
during cooking to spread more
horizontally rather than vertically. They
therefore tend to rise diagonally
upwards. To ensure that all vapour can
be extracted, the cooker hood should
sufficiently cover the cooking area. The
hood should be significantly wider than
the hob where possible; at the very
least it should be of the same width.
Island hoods in particular need to be
wider and deeper than the hob due to
the cross-flow of air in the room.
Wall hoods with edge extraction are
better at catching vapours due to the
higher operating speed so a wall hood
can be the same width as the hob.
Hob width
Recommended width of the cooker hood
Up to 70 cm
90 cm
Up to 90 cm
120 cm
Installation height/safety
distances
WARNING!
For safety reasons, it is important to
observe the minimum recommended
distance to the hob when determining
the installation height for a cooker hood.
Failure to observe this minimum
distance can cause damage to heatsensitive components in the cooker
hood.
The installation height is primarily
determined by the design of the hob
and cooker hood. The distance
between cooker hood and hob is
usually between 40 and 75 cm. Refer to
the manufacturer's instructions for the
individual cooker hood for further
details. A larger distance is often
required for gas hobs.
Examples depending on model and
manufacturer:
– 500 mm for flat-screen hoods
– 400 mm for headroom-free wall
extractors
– 1500 mm for ceiling extractors
Observe the installation instructions and
technical data provided by the
appliance manufacturer (cooker hood
and hob).
28
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H
When determining an installation height
for a cooker hood, it is also advisable to
ensure that the user has a clear view
and unimpeded access to the hob/
cooking area. If this cannot be achieved
using the values stated, the hood
should be placed higher. However, the
maximum distance of 750 mm or as
stated by the manufacturer should not
be exceeded. If the cooker hood is
installed any higher, it will lose
effectiveness and air extraction will be
less efficient. If the cooker hood is to be
installed at a greater height, it is
advisable to adjust the hood width
accordingly.
29
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PLANNING Information on woks, deep fat fryers, grill pans and similar
Information on woks, deep fat
fryers, grill pans and similar
Woks, deep fat fryers, grill pans and
similar (griddles, teppan yaki, etc.)
generate a great deal of heat in just a
few minutes, causing rapid vapour
generation. This can result in relatively
strong development of smoke and
vapour.
The following aspects should therefore
be taken into consideration when
planning the use of a cooker hood
above these types of cookware:
– An extraction hood should always be
used rather than a recirculation hood.
This type of hood is particularly
effective at cleaning the room air as it
blows smoke and heat outside.
30
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– If possible (e.g. when arranging
individual cooking areas or module
systems), woks, deep fat fryers, grill
pans etc. should always be placed
centrally under the cooker hood.
– Cooker hoods that extract air over an
entire panel or feature multi-zone
edge extraction are better suited than
hoods with edge extraction. These
are better at capturing the vapour
from this type of cooking, which is
generated centrally and rises relatively
steeply.
Information on large gas hobs PLANNING
Information on large gas hobs
Recirculation hoods are not permitted
for large gas hobs with a nominal
output of between 11 and 18 kW (e.g. a
gas hob with more than four burners or
a gas hob with additional wok burner).
An extraction hood and sufficient intake
air or a controlled domestic ventilation
system must be provided.
This must provide a minimum airflow of
15 m3/h per kW total nominal output.
Appropriate intake air openings must
be provided (technical regulations for
gas installations).
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PLANNING
Recommended
operating mode
Extraction is still the most effective method of
removing vapours from the kitchen. Structural
conditions and legal requirements have a
significant influence when deciding which
kitchen ventilation system to install. Heat loss
throughout the house is becoming an increasingly
important consideration.
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PLANNING Extraction or recirculation
Energ y-efficient houses PLANNING
Important aspects of extraction
or recirculation hoods
Aspects to note:
the more important criteria. For detailed
explanations, please see the
corresponding chapters.
Operating modes
Extraction
Recirculation
Required
Required
Not required
Required
Discussion required with
architect, ventilation
engineer, etc.
Possible; discussion
recommended with
architect and/or
ventilation engineer
Extractor ducting
Required
Not required
Wall vent
Required
Not required
Ensure intake air supply,
window contact switch
Possible
Required
Not required
Room airing after cooking
Not required
Required
Grill pans, woks, deep fat
fryers
Possible
Not recommended
Large gas hob (more than
11 kW)
Possible
Grease filter
Odour filter (active carbon
filter)
Energy-efficient house
Low-energy house
Energy-efficient house,
passive house*
Open fireplaces
Intake air
*Ultra low energy house
This section must be updated by local
This section must be updated by local
markets during
markets translation.
during translation
Various aspects need to be taken into
consideration when making a decision
for a recirculation or extraction hood.
The following is an overview of some of
Energy-efficient houses
A number of different terms are
used to describe energy-efficient
houses, depending on the
underlying standard:
– Low-energy house pursuant to the
German Heat Insulation Ordinance
1995 (WSVO 95) or Energy Saving
Ordinance 2009 (EnEV)
– Ultra-low-energy house (passive
house), 3 litre house according to DIN
4108-6 and DIN 4701-10
– Efficient house 40, 55, 70 according
to KfW and EnEV
– Passive house according to the
Passive House Design Package
(PhPP)
– Zero (heat) energy house (no fossil
fuels)
Common to all of these standards is the
fact that the houses have significantly
reduced heating requirements or are
even largely self-sufficient due to their
design.
The ventilation of the kitchen and the
entire house must therefore be taken
into careful consideration when
Energy-efficient house
Not permitted
Low-energy house
(newbuild or refurbished
building)
Passive house
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selecting the type of cooker hood in an
energy-efficient house. The many
complex requirements for energyefficient houses also require due
consideration. In practice, this means
that the architect and/or ventilation
engineer need to be consulted.
Main objectives of ventilation
planning:
– Capturing the grease and dirt
particles from the cooking vapours so
that they do not enter the domestic
ventilation system
– Removing the moisture from the
kitchen air so that it does not cause
any damage through condensation
and enables maximum heat retention
– Ensuring sufficient intake air
(especially in extraction mode)
General rules:
Recirculation hoods can be used in any
energy-efficient house, but extraction
hoods can only be used under certain
conditions.
Extraction
Recirculation
Allowed in some
circumstances
Possible
Allowed in some
circumstances
Possible
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PLANNING Energ y-efficient houses
The availability of a central ventilation
system in the house or apartment plays
Energ y-efficient houses PLANNING
an important role in the choice of
operating mode.
Moisture removal:
By the user when
using a recirculation
hood
Characteristics:
– Manual (brief, intensive – Automatic
airing)
– Controlled
– Uncontrolled
Structural requirements:
– None
Recirculation hoods are often used in
energy-efficient houses with an existing
ventilation system.
A domestic ventilation system with heat
recovery removes the moisture in the
living room air in a controlled manner
and uses a heat exchanger to reclaim
the heat. If a recirculation hood is used,
additional strain is placed on the
domestic ventilation system due to the
moisture generated from cooking.
It is important to note that this will
generally shorten the maintenance
interval for the ventilation system. This is
because the increased strain can lead
to heavier soiling of the ventilation
system and reduce the efficiency of the
heat exchanger and filters.
For reasons of fire prevention, it is
important for recirculation hoods to
capture the maximum amount of
36
BMEECH13LL146002_Pages.indd 37
By extractor hood
– Extractor duct that is
independent of the
domestic ventilation
system
– Intake air
– Energy-efficient wall
vent (blower door
certificate)
vent, heat is lost as soon as the room is
aired — and brief, intensive airing after
cooking is required to remove the
excess moisture. Many users find it
difficult to monitor and control the airing
process. If users do not air the room
enough or if they forget to air the room,
the loss of heat may be relatively low
but too much moisture will be retained
in the room. This will result in
condensation damage and mould (see
chapter "Room climate", page 10).
Airing the room for too long, however,
will lead to excessive loss of heat.
Considering the above, the use of an
extraction hood appears to be the best
solution for energy-efficient houses
without domestic ventilation systems. It
is always advisable to have an expert
(e.g. ventilation engineer) check whether
such hoods are permissible, if sufficient
intake air is guaranteed or if there are
any reasons not to install an extraction
hood — not least because the
regulations and grants available for new
and old buildings, single family
dwellings and apartment buildings are
different.
For this reason, discussions must
always be held with the architect and/or
ventilation engineer in order to devise a
suitable ventilation concept.
grease and dust particles so that these
do not enter the domestic ventilation
system.
An additional intake air source is
required for extraction hoods due to the
increased discharge of air during
cooking. Under no circumstances is it
permitted to connect an extraction
hood to a ventilation system. In addition
to removing grease and dust particles,
extraction hoods also convey moisture
outdoors in a controlled manner. It is
important to select a lossless wall vent
(blower door certificate) for this. This
type of wall vent will only open when
the cooker hood is in operation. When
not in use, it closes to create an air-tight
seal and therefore provides a good level
of heat insulation (see page 43 ff).
Although the use of a recirculation hood
prevents the loss of heat through a wall
37
13.11.13 17:18
PLANNING
Important aspects
of planning exhaust
air ducting
The effectiveness of the cooker hood system results
from the interplay between the cooker hood and
the exhaust ducting components. The decisive
factor here is to keep the frictional resistance in
the ducts as low as possible to prevent any
reduction in fan performance.
38
BMEECH13LL146002_Pages.indd 38-39
39
13.11.13 17:18
PLANNING Characteristic curve of a cooker hood
Characteristic curve of a cooker hood PLANNING
Characteristic curve
of a cooker hood
The characteristic curve of a cooker
hood shows how it behaves under
different operating conditions. This
diagram shows the relationship
between counter pressure and airflow
rate for a specific cooker hood and
connected ducting, as well as the
relationship between counter pressure
and the noise level (acoustic power).
Characteristic curves X, Y and Z show
these relationships for the three power
settings on the cooker hood. For
example, the point where characteristic
curve Z intercepts the baseline (x-axis)
shows that the airflow rate for this hood
is 460 m³/h at power setting 3
(characteristic curve Z) and 0 pascal
counter pressure. Counter pressure of
0 pascal exists only when the airflow
rate is measured directly at the fan
outlet of the cooker hood (= free
blowing, see chapter "Airflow rate in
accordance with IEC 61591", page 67).
When the counter pressure increases
(e.g. by connecting the extractor
ducting), the airflow rate decreases.
Characteristic curves A, B and C show
how greatly the two values change
when three sets of example extractor
ducting (with different cross sections)
are connected. If the extractor ducting
Example:
ACTUAL COOKER HOOD CHARACTERISTIC CURVE X, Y, Z (LOAD
LEVEL 1, 2, 3)
Counter pressure ∆P (Pa)
400
THEORETICAL DUCT
CHARACTERISTIC CURVE
Sound power dB
(A) re 1 pW
Z
Y
X
A Ø 100 mm
200 m3/h
60 Pa
Typical cooker hood
characteristic curve
300
A
200
3
B
70
2
Working points
C
100
0
1
100
40
BMEECH13LL146002_Pages.indd 40-41
200
230
245
260
265
400
310
385
345
420
350
440
360
460
The extractor ducts with characteristic
curves C and A primarily differ in terms
of their cross section. In general, the
larger the ducting cross section, the
lower the counter pressure and the
higher the airflow rate. Extractor ducting
with larger cross sections should
therefore be the preferred approach.
However, the level of counter pressure
is not only influenced by the cross
section of the extractor ducting. It also
depends on the structural design of the
extractor ducting (material and shape,
changes in cross section, number of
diversions etc.). The less favourable the
layout, the more vertical the ensuing
characteristic curve. When designing
the extractor ducting layout, all
necessary measures must therefore be
taken to keep the counter pressure
created by connecting the ducting to a
minimum.
The diagram also shows that an
increase in the counter pressure in the
extractor ducting also involves an
increase in the noise level (acoustic
power). In this case, reducing the cross
section of the extractor ducting from
150 mm (curve C) to 100 m (curve A)
causes the acoustic power to increase
from a whisper-quiet 49 dB (A) re 1 pW
to 70 dB (A) re 1 pW, which is as loud
as a vacuum cleaner. This is another
reason why the counter pressure
created when connecting the ducting
should be kept to a minimum.
Poor extractor ducting cannot be
compensated for by using a more
powerful cooker hood. This would
simply increase the level of loss and
generate more noise.
TIP
It is only possible to achieve a high
airflow volume and low noise level by
using extractor ducting that provides
low resistance (see the chapter
"Information on exhaust air ducting",
page 35).
B Ø 125 mm
200 m3/h
30 Pa
60
50
300
with characteristic curve C is
connected, for example, the counter
pressure increases to 70 Pa and the
airflow rate falls to 440 m³/h. However, if
the extractor ducting with characteristic
curve A is connected, the counter
pressure increases to 180 Pa and the
airflow rate falls to 385 m3/h. In general,
the following applies: the lower the
counter pressure following connection
of extractor ducting, the lower the
impact on the airflow rate of the hood.
C Ø 150 mm
200 m3/h
15 Pa
500
Flow volume
(m3/h)
41
13.11.13 17:18
PLANNING Exhaust ducting
Exhaust ducting PLANNING
Information on exhaust air ducting
The planning and design of extractor
ducting has a significant influence on
the airflow rate and the noise level of the
cooker hood. This is because each
component in the ducting introduces
counter pressure (frictional resistance),
which leads to a reduction in the airflow
rate in the cooker hood and increases
the level of noise.
The frictional resistance within the
ducting is dependent on a number of
factors:
– Cross section of the exhaust air
ducting
– Length of the exhaust air ducting
– Bends/curves in the exhaust air
ducting
– Material and type of ducting (the
material must also be approved for
use with a cooker hood in
accordance with fire prevention
regulations)
The following sections provide
assistance with selecting the right
components when planning extractor
ducting.
Cross section of the exhaust air
ducting
The cross section of the ducting must
be adapted to match the airflow rate of
the cooker hood and the ducting
routing (length and design). A cross
section that is too narrow will result in
significant losses in the airflow rate and
increase the noise level. The ventilation
performance of the cooker hood is the
key factor for determining the ducting
cross section. The more powerful the
ventilation performance, the greater the
ducting cross section must be.
42
BMEECH13LL146002_Pages.indd 42-43
As a rule, the larger the cross section,
the less counter pressure is created in
the ducting.
The following exhaust air ducting
specifications serve as a guide:
Ø 125 mm for a ventilation performance
of < 500 m3/h
Ø 150 mm for a ventilation performance
of > 500 m3/h
Any reduction in the cross section of
the ducting must be avoided.
This would give rise to
turbulence, which
would generate a high
amount of counter
pressure. The more
rapid airflow speed
associated with a
narrowing in the cross
section also cause
the level of noise to
increase.
Unavoidable reductions in the cross
section should always be made at a flat
angle (not a 90° angle). This is the only
way to keep air turbulence and
increased counter pressure to a
minimum.
By contrast, increases in the cross
section have a positive effect on
counter pressure.
Exhaust ducting material and shape
The market for extractor ducting is very
broad and highly diversified. Products
differ in their shape, dimensions and
material (plastic, metal, textile).
Smooth-walled plastic ducts are the
most favourable form of ducting from a
technical airflow perspective and are
particularly suitable for straight duct
routes/runs. These should be used if
the structural requirements are met.
Flexible aluminium ducting (aluflux) also
achieves reasonably good flow values
when elongated. It is more flexible than
rigid plastic ducting and Glattwandiges
adapts well
to
Rohr
differing structural conditions.
Unnecessary bends should, however,
be avoided.
Corrugated and spiral ducts are the
least favourable from a technical airflow
perspective. The wave-like
surface
Aluflex-Rohr
results in a large amount of turbulence,
even if the ducting is pulled taut. When
the film is heated by the extracted air, it
stretches. This leads to even greater
turbulence and the flapping film
generates noise. Glattwandiges Rohr
A distinction is made between round
and flat channels. Flat channels are
often used in practice for both visual
and technical reasons. It used to be
believed that the flow conditions in flat
channels were less favourable.
However, this no Aluflex-Rohr
longer applies as a
general rule. Recent developments in
flat channels can provide similar or
better airflow results than a round
channel.
They are characterised by the following
features:
– The inner cross section of the flat
channel must correspond at least to
the cross section of the exhaust air
Flow resistance: low
–> minor losses
Flachkanal
Smooth-walled
ducting
Glattwandiges Rohr
Glattwandiges Rohr
High
flat channel
Flachkanal
Aluflex-Rohr
Flexschlauch
Aluflex ducting
Aluflex-Rohr
Low
flat channel
Flachkanal
Flexible tubing
Flexschlauch
Flow resistance: high
–> high losses
socket in the cooker hood. The
surface area should therefore equate
to the cross section
of a 150 mm pipe
Flachkanal
if the exhaust air socket has a
diameter of 150 mm.
– The width-to-height ratio must be
optimised. The higher the flat channel,
the more favourable its airflow
qualities (e.g. 89 x 222 mm)
– Bends are equipped with guide plates
that significantly reduce turbulence
(low-resistance diverters).
43
13.11.13 17:18
PLANNING Exhaust ducting
Exhaust ducting PLANNING
Length of the exhaust ducting,
curves and bends
As the length of the exhaust ducting
increases, the counter pressure (duct
resistance) increases and the airflow
rate decreases.
Bends and curves are problematic as
they present deflection surfaces that
dam the airstream and generate
turbulence. This causes an increase in
counter pressure. Bends and curves in
the ducting should therefore be kept to
a minimum. If bends and curves are
required for structural reasons, bends
with the largest possible radius are
advisable. The smaller the bend radius,
the greater the counter pressure.
Corners at right angles should also be
avoided because these lead to even
greater pressure losses and therefore a
loss of performance.
EXHAUST CHANNELS WITH GUIDE PLATES – ADVISABLE
Diverter
Vertical bend
Guide plates can be used in curves and
bends to control the airflow and avoid
disruptive turbulence. When compared
to conventional bends, this results in up
to 79% less pressure loss in flat
channels and up to 70% less in round
channels. (Source: Naber).
45° bend
advisable
90° bend
advisable
90° bend with guide plates
advisable
The following comparison between
different duct types and flat channels
Horizontal bend
TIP
The following rule of thumb applies for
good duct routing: the distance
between two bends should be at least
1 m, although 1.5 m is better.
indicates the extent to which the
material used can influence airflow loss.
COMPARISON BETWEEN CHANNEL SYSTEMS WITH A
SQUARE CROSS SECTION
Airflow rate
100 %
80 %
Exhaust air
route
C: 65 %
60 %
40 %
Square 90° bend
not advisable
90° bend – spiral ductingless
advisable
90° bend – spiral ducting
squashed
not advisable
B: 92 %
E: 83 %
D: 81 %
A: 35 %
20 %
0
Stand pipe 90° bend
Exhaust air pipe
elements
3 m channel 2 x
1 m channel
90° bends
A Flat channel (100 mm)
B Naber Compair Flow 150*
C Flat channel (125 mm)
D Naber Compair Flow 125*
E Flat channel (150 mm)
* with guide plates
At an atmospheric pressure of: 1017.9 mbar, room temperature: 27.7 °C, relative humidity: 43% rH.
(Source: Naber).
44
BMEECH13LL146002_Pages.indd 44-45
45
13.11.13 17:18
0
Stand pipe 90° bend
Exhaust air pipe
elements
3 m channel 2 x
1 m channel
90° bends
D Naber Compair Flow 125*
E Flat channel (150 mm)
PLANNING Exhaust ducting
Exhaust ducting PLANNING
COMPARISON BETWEEN CHANNEL SYSTEMS WITH A ROUND
CROSS SECTION
Airflow rate
100 %
A: 94 %
D: 90 %
B: 89 %
80 %
Exhaust air
route
C: 72 %
F: 71%
Performance loss calculation —
example
The following example serves to explain
the degree of ventilation performance
achieved in consideration of the
individual exhaust ducting and the
ducting material and diameter:
An extraction hood is to be installed in a
kitchen measuring W = 3 m, D = 4 m,
H = 2.4 m. The extractor's maximum
free-blowing output is 670 m3/h.
Exhaust air will be expelled to the
outside through a rigid exhaust duct
with a diameter of 150 mm. The duct
length of 5 m includes two 90° bends,
a backflow trap and an extractor rain
hood.
60 %
E: 54%
40 %
Result:
The required airflow rate is 138–276
m3/h; the cooker hood is therefore
suitable for this kitchen.
A Naber Compair Round 150
G: 23 %
20 %
0
Stand pipe 90° bend
Exhaust air pipe
elements
B Conventional round channel 150
C Conventional round channel 125
D
E
F
G
Naber Compair Round 125
Flexible tubing Ø 125, fixed
Flexible tubing Ø 150, fixed
Flexible tubing Ø 100, fixed
3 m channel 2 x
1 m channel
90° bends
At an atmospheric pressure of: 1017.9 mbar, room temperature: 27.7 °C, relative humidity: 43% rH.
(Source: Naber).
Auxiliary fans
The question of whether to use an
auxiliary fan in longer stretches of exhaust
ducting to maintain ventilation
performance is frequently discussed. The
following needs to be taken into
consideration:
Each fan has its own characteristics with
regard to the blade geometry, drive motor
axis bearing, fan impeller and operating
speed levels. Taken together, these
factors define its characteristic curve.
In the case of an extractor system, an
auxiliary fan would be installed in the
downstream volume flow and would have
to handle the air volume arriving based on
46
BMEECH13LL146002_Pages.indd 46-47
the upstream conditions. Even if the fan
had the same characteristic curve as the
main fan, the "distance between the two"
interference factor, i.e. the non-identical
conditions on the intake and outlet side,
would result in asynchronous
functionality. This would reduce the overall
performance.
This approach would also require the fans
to be triggered electrically at the same
time. Although it would make most sense
to do this using the same switch on the
hood, such an approach - is frequently
not taken into account in the design.
Use of an auxiliary fan is not therefore
recommended.
Answer to 1.:
Kitchen room volume = (W x D x H) 3 x
4 x 2.4 m = 28.8 m³ 28.8 m³ - 20%
(kitchen fittings) = 23 m³
(the decision on whether to deduct
20% for kitchen fittings or keep it as a
performance reserve can be made on
an individual basis)
Required airflow rate:
138 – 276 m³/h
(the air in the room needs to be
recirculated 6–12 times each hour)
Questions:
1. Is the airflow rate of the cooker hood
described above sufficient for the
kitchen in question? How high should
it be?
2. Is the airflow rate still sufficient given
the specifications of the exhaust
ducting? How high is it?
Answer to 2.:
The following examples of calculation
values for duct resistance were
published by the Swiss Kitchen
Association. (Values may vary
depending on shape and manufacturer)
Calculation value for duct resistance
SMS Swiss measuring system for kitchens / EURO Euro measuring system for kitchens
Pipe
–
NW
Ø mm
100
125
150
Airflow
Air speed
Rigid
rate in the in the
metal
pipe
pipe
pipe
3
m /h
m/sec
Pa/m
100
3.5
2.0
150
4.1
3.0
200
7.0
7.0
250
8.8
10
300
10.6
13
400
14.2
28
500
17.4
35
200
4.5
2.0
250
5.7
3.0
300
6.8
5.0
400
9.1
8.0
500
11.3
13
600
13.9
17
700
16.3
21
200
3.1
0.9
300
4.7
1.8
400
6.3
3.3
500
7.8
5.0
600
9.4
7.0
700
10.8
9.0
800
12.4
11
Flexible
Aluflex
pipe
Pa/m
3.0
4.0
9.0
13
17
36
53
3.0
4.0
6.0
10
17
23
30
1.1
2.4
4.3
6.5
9.1
12
16
Rigid
metal
bend
90°
Pa
3.5
5.5
15
23
35
62
95
6.0
10
14
26
40
61
82
3.0
7.0
12
19
28
38
48
Specific resistance values in Pa
Flexible
TeleExhaust
pipe bend scopic
rain
90°
wall pipe hood
Pa
(TWP) Pa
Pa
5.0
36
–
7.5
50
7.0
20
74
22
30
102
32
45
145
48
81
226
84
125
–
122
8.0
40
6.0
13
50
10
18
67
14
34
122
24
52
180
37
80
260
55
105
–
78
4.0
27
4.0
10
55
7.0
16
84
13
25
117
20
37
175
28
50
240
37
63
–
47
Reduction
125/100
150/125
180/150
Pa
–
–
–
–
–
–
–
24
37
53
98
148
218
–
7.0
17
30
45
66
88
118
Backflow
trap
Pa
30
35
42
48
56
80
102
20
22
25
30
44
55
68
13
18
20
24
30
35
47
10 Pa (Pascal) equal 1 mm WC (water column)
47
13.11.13 17:18
PLANNING Exhaust ducting
Exhaust ducting PLANNING
Calculation of the air resistance in the
exhaust duct:
Required pipe material x specific air
resistance
5 m pipe x 9 Pa/m
= 45 Pa
2 x 90° bends x 38 Pa/m = 76 Pa
Backflow trap
= 37 Pa
Exhaust rain hood
= 35 Pa
Total air resistance
= 193 Pa
The characteristic curve for the cooker
hood can now be used to determine
whether the ventilation performance of
the hood is sufficient using this exhaust
ducting.
Condensation in the exhaust duct
Condensation can form when the warm
extracted air flows through cooler
ducting. To allow the condensate to
drain, level extractor ducting must be
installed with an angle of inclination of
approx. 2° to the exterior wall.
ANGLE OF THE EXHAUST DUCTING
2˚
CHARACTERISTIC CURVES
Pa
500
PIPE Ø 125 mm
= 415 Pa
400
300
PIPE Ø 150 mm
= 193 Pa
200
100
0
100
200
300
400
200 m3/h
Result:
Using extractor ducting with a diameter
of 150 mm at a specific air resistance of
193 Pa results in ventilation
performance of 580 m³/h, which is
more than sufficient for the situation in
this example. The specific air resistance
at a diameter of 125 mm is 415 Pa. The
48
BMEECH13LL146002_Pages.indd 48-49
500
600
700
800
m3/h
580 m3/h
ventilation performance at maximum
output is 200 m³/h — the required value
is 273 m³/h.
The longer the extractor ducting and
the more bends it includes, the higher
the performance losses.
The installation of a condensation trap
is recommended if vertical ducting is
fitted (e.g. ducting that passes through
a cold loft). Any condensate in the
ducting is collected in the condensation
trap and evaporates. Make sure the
trap is installed immediately above the
hood's exhaust air socket, i.e. at the
lowest point of the exhaust duct. As a
general rule, sufficient insulation must
be provided in cold areas of the
exhaust ducting and around the air
outlet to prevent the formation of
condensation to the greatest extent
possible.
CONDENSATION TRAP
49
13.11.13 17:18
PLANNING Exhaust ducting
Wall vent
A distinction needs to be made between
exhaust air wall vents and exhaust/intake
air wall vents. An exhaust air wall vent
covers the opening in the wall and is
used to convey the exhaust air from a
cooker hood outside. An exhaust/intake
air wall vent also allows fresh air to flow
into the kitchen.
Both types of wall vent need to fulfil a
number of requirements. They need to
be designed so that the exhaust air can
flow out with as little pressure loss as
possible. They must, however, also be
capable of creating an air-tight seal in the
wall opening so that room heat does not
escape or cold enter the room from
outside when not in use, which is usually
longer than the operational time. These
requirements are fulfilled to a greater or
lesser extent depending on the individual
design and method of operation.
Conventional exhaust air wall vents
consist of an exterior cover, usually in the
form of rigid gravity flaps, and an internal
backflow trap that prevents the
unwanted ingress of outdoor air.
Depending on the design of the gravity
Exhaust ducting PLANNING
flaps, the air stream is deflected to a
greater or lesser extent, which can result
in large pressure losses. This significantly
reduces the efficiency of the cooker
hood and increases the level of noise.
Modern exhaust air wall vents, which are
referred to as "lossless wall vents",
reduce these effects. Optimising the
exhaust outlet cover will significantly
reduce pressure losses. The cover
opens only when the cooker hood is
switched on. When the cooker hood is
not in use, the vent closes to create an
airtight seal, thereby providing improved
heat insulation. Lossless wall vents are
either mechanically operated or motor
driven.
For instance, there is a mechanically
operated exhaust air wall vent designed
so that the outer cover consists of a
stainless steel plate mounted on a slide
with ball bearings. When the cooker
hood is not in use, the slide is held in
place by springs and additional magnets
and the front plate seals the opening.
Once the cooker hood is switched on,
the ensuing air pressure forces open the
front plate on the slides. The pressure
losses with this type of wall vent are
relatively low as it does not require a
backflow trap and the air being expelled
is not diverted to the same extent as
with gravity flaps. When closed, these
wall vents also provide such a good level
of thermal insulation that they are
permitted under EnEV09 (German
Energy Savings Ordinance) and are
suitable for use in energy-efficient
houses (blower door certificate).
Motor-driven wall vents also exist that
are certified for use in energy-efficient
houses (blower door certificate). The wall
vents are opened and closed by the
cooker hood or by an airflow monitor
inside the wall vent. Motorised wall vents
need a power supply (plug socket) and
also an electrical connection (cable)
between the wall vent and hood if
controlled via the hood.
In exhaust/intake air wall vents, the
channels and openings for the exhaust
and intake air are arranged either next to
or on top of each other, depending on
the design. Both channels are fitted with
an air flap that pivots around the same
axis. When the cooker hood is switched
on, the exhaust air forces open both air
flaps. At a low power setting, the air
pressure in the exhaust channel remains
low. The flaps only open slightly and only
a small amount of air can flow in or out.
At the highest power setting, the air
pressure in the exhaust channel is high.
The flaps open to the maximum extent
and a large amount of air flows in or out.
Irrespective of the power setting
selected, the same volume of intake air
enters the kitchen as the volume of air
that is extracted. An exhaust/intake air
wall vent alone will not usually suffice in
conjunction with open heating
appliances (chimney etc., see page 51).
EXHAUST AIR WALL VENT WITH BLOWER DOOR CERTIFICATE
EXHAUST
AIR
EXHAUST
AIR
50
BMEECH13LL146002_Pages.indd 50-51
51
13.11.13 17:18
PLANNING Exhaust ducting
Advantages of installing an
exhaust/intake air wall vent:
– Only one hole is required in the wall.
– There is no risk of the intake air being
routed incorrectly and causing
draughts.
The following sketch shows the
principles behind the operation of
exhaust/intake air wall vents:
PLANNING
When installing a wall vent, it should be
ensured that the nominal width (inner
cross section) matches the nominal
width of the upstream extractor ducting.
It must not be any smaller. A reduction in
the cross section would severely
decrease the performance of the cooker
hood and increase the noise level.
Why does exhaust
air need intake air?
SCHEMATIC DIAGRAM: EXHAUST/INTAKE AIR WALL VENT
INTAKE AIR
EXHAUST AIR
INTAKE AIR
FROM LEAKS
Wall vents are available in the following
three main nominal widths (NW):
NW 200 mm/150 mm/125 mm
If necessary, the nominal width of the
wall vent can be larger than that of the
upstream exhaust duct and connected
to the duct by means of a reducing
adaptor.
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BMEECH13LL146002_Pages.indd 53
Wall vents are usually telescopic, i.e. they
can be fully adjusted to the thickness of
the wall.
A cooker hood that expels the air from the kitchen
to the outside needs an equalising intake air
supply. Certain issues regarding intake air need
to be considered to ensure the cooker hood system
works to full capacity.
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PLANNING Exhaust air needs intake air
Exhaust air needs intake air PLANNING
Exhaust air needs intake air
When cooker hoods are operating in
extraction mode, the filtered room air is
conveyed outdoors and thus leaves the
room. If none or too little fresh air flows
back into the kitchen from outside,
negative pressure is created. If the
negative pressure is not equalised it will
lead to an increase in the hood's motor
speed and noise level and also to a
reduction in airflow and air exchange.
As odorous substances will remain in
the room, the air purification is
significantly lower. Extraction hoods
must have sufficient intake air — equal
to the amount they expel to the outside.
Here are some examples of how
intake air can be provided:
– Tilted window, combined with a
window contact switch if applicable.
The window contact switch ensures
that the cooker hood can be used
only if the window is open.
– Electrically driven windows that open
and close in parallel to the operation
of the cooker hood.
– Ventilation grilles, e.g. at the top of the
kitchen door or above a window.
– Adjoining living rooms if they are not
separated by closing doors.
– Exhaust/intake air wall vent.
To ensure that the vapours rise vertically
to the cooker hood for extraction and
are not blown away by the incoming air,
steady air circulation must be provided
in the kitchen and intrusive cross-flows
or air turbulence must be avoided. In an
ideal situation, cold air will enter the
room from a vent in the wall opposite
the cooker hood. This cold air will
capture any existing vapours in the
kitchen as it drops. As it then rises
above the hob, it will capture as many
of the vapours there as possible and
expel them via the hood.
The following points must be taken
into consideration in order to come
as close to this ideal scenario as
possible:
– The intake air should come from the
opposite side of the room where
possible.
– If the intake air is provided by an open
window on the opposite side of the
room, other windows and doors
should remain closed.
– If possible, install the ventilation grilles
and wall vents directly beneath the
ceiling (not close to the floor).
– The intake air element should be
located at least 2 m from the cooker
hood.
AIR MOVEMENT WITH INTAKE AIR - OPEN DOOR AT OPPOSITE
SIDE OF THE ROOM
INCORRECT
CORRECT
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55
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PLANNING
Please adapt locally
Legal requirements
concerning exhaust
air and intake air
ducting
– German Ordinance on Combustion
Equipment (FeuVO)
– Local building codes (installation of
wall vents)
– Neighbours' rights
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57
MarkUp - TBC - There is content in the brochure
which has to be updated locally!
13.11.13 17:18
PLANNING Expelling exhaust air through chimneys
Ambient air heating appliances PLANNING
Expelling exhaust air through
chimneys
Ambient air heating
appliances
The exhaust air may not be routed
through actively used chimneys or
smoke flues. Approval must be granted
in advance by the responsible chimney
inspector before routing exhaust air
through a chimney or smoke flue that is
no longer in use.
If a disused chimney is used to expel
exhaust air, diverters must be used to
feed the exhaust air into the chimney in
a way that ensures the air is blown
upwards.
The following notes apply to extraction
hoods (not to pure recirculation hoods)
in combination with heating appliances
dependent on a flow of ambient air (not
for self-enclosed heating appliances):
Since brick chimney walls are usually
very rough and uneven, air turbulence
and pressure losses may be
experienced, especially if the chimney
cross section is narrow. Grease
particles will also be deposited on the
rough surfaces (fire hazard). It is
therefore advisable to place extractor
ducting with flat walls in the chimney.
GUIDING EXHAUST AIR THROUGH A CHIMNEY
NOT ADVISABLE
When installing an extraction hood in
rooms with heating appliances
dependent on ambient air such as
wood burners, open fires or gas-fired
boilers, it is essential to ensure a
sufficient supply of intake air. This is
because operating both simultaneously
can result in negative pressure strong
enough to prevent the combustion
gases from escaping through the
chimney/flue and can draw the gases
into the room instead. Combustion
gases are toxic and can prove harmful
or even fatal to the occupants. The
German Ordinance on Combustion
Equipment (FeuVo) specifies that
simultaneous operation must not lead
to a negative pressure in excess of 4 Pa
(= 0.04 mbar).
The installation of an exhaust/intake air
wall vent may provide sufficient intake
air in individual cases. In most cases,
however, the cross section of the air
intake in wall vents is not sufficient to
ensure that the negative pressure does
not exceed 4 Pa. The installation of a
window contact switch (additional
where necessary) is sufficient to
guarantee adequate ventilation. This
ensures that the hood can be operated
only when the window is open. Window
contact switches do not check whether
the heat-producing appliance is in use
when the cooker hood is switched on.
It is now possible to use a radiocontrolled temperature sensor in the
chimney to detect whether the heatproducing appliance is in use. This
enables cooker hood operation even
when the window is closed if the heatproducing appliance is not in use,
thereby preventing heat loss.
TIP
The responsible chimney inspector
must always be consulted when planning the use of an extraction hood in a
room with a heating appliance dependent on ambient air.
ADVISABLE
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59
13.11.13 17:18
PLANNING Legal regulations for the installation of wall vents
Legal regulations for the
installation of wall vents
Local authorities may issue municipal
building codes that apply within their
sphere of influence. These may include
regulations on installing wall vents for
extractor hoods. During the planning
phase, it is therefore advisable to
contact the local building authority and
check whether any such regulations
exist. Any regulations that do exist must
be observed.
Neighbours may soon be annoyed
by kitchen vapours wafted towards their
house. It is therefore advisable to obtain
approval from neighbours for the
location of a wall vent connected to an
extraction hood, especially when there
are no local construction regulations. To
avoid conflicts, it is also advisable to
place the sleeve as high as possible
and maintain the maximum distance
possible from neighbours' windows (at
least 2 m).
At a glance PLANNING
AT A GLANCE
– The cooker hood should be wider
than the hob; at the very least it
should be of the same width.
– Compliance with the minimum
distance between the hob and
cooker hood as specified by the
manufacturer is mandatory.
– Specific hob characteristics (gas
hob, deep fat fryer, etc.) must be
given due consideration
– Energy-efficient houses place
particular demands on the
ventilation system. Recirculation is
always an option. Extraction
systems can only be used in lowenergy houses under certain
circumstances. The architect and/
or ventilation engineer must be
consulted.
The following applies to exhaust
air ducting for extraction hoods:
– Select the largest possible cross
section
– Use pipes and channels with
smooth walls
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BMEECH13LL146002_Pages.indd 60-61
– The higher the flat channel, the
more favourable its airflow qualities.
– The exhaust air duct should be as
short and straight as possible with
no reducing adapters and as few
diverters as possible.
– Diverters (90° bends, etc.) with
internal guide plates are best for
maintaining the ventilation
performance.
– Wall vents that are air-tight when
closed cause less heat loss and are
therefore highly advisable; some
may also be suitable for energyefficient houses.
– Exhaust air needs intake air —
ensure an adequate intake air
source is available.
– Legal requirements must be
considered before installing an
extraction hood.
– An intake air source is mandatory
for heating appliances dependent
on ambient air (e.g. wood-burning
stoves), for instance via a window
contact switch.
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Appliance selection
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APPLIANCE SELECTION
The technology
of cooker hoods
Most cooker hoods feature the same basic
design. They all have a grease filter.
Recirculation hoods also have an active carbon
filter (see chapter "Filter types", page 61).
The main differences with regard to efficiency
and noise levels lie in the type of motor/fan
and also whether kitchen vapours are extracted
via edge or surface extraction.
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65
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Centrifugal fan inverter motor APPLIANCE SELECTION
APPLIANCE SELECTION Design of a cooker hood
Design of a cooker hood
Centrifugal fan
The fan is the heart of every cooker
hood. It comprises a fan wheel and a
drive (motor). The fan sucks up and
expels kitchen vapours. The fan is
In units with centrifugal fans, the air is
sucked in parallel or axially to the fan/
rotor disc drive axis, diverted 90° by the
rotation of the radial rotor disc and
usually incorporated in the hood
assembly. Most cooker hoods use
centrifugal fans.
Backflow trap
Telescopic chimney
blown out radially to the drive axis. The
centrifugal force of the rotating fan
blades causes pressure acceleration of
the air stream, which is further
heightened by a narrowing in the outlet
cross section of the fan housing. The
generation of this relatively high
pressure potential is the key benefit of a
centrifugal fan. This type of fan is
therefore particularly well suited to
longer stretches of ducting with a
narrow cross section. Centrifugal fans
achieve airflow volumes from 250 to
more than 800 m3/h and are the
preferred design for cooker hoods.
Backflow trap
Extractor ducting
Control
Grease filter
Operation
Centrifugal fan
Active carbon filter
Inverter motor
The use of inverter motors in cooker
hoods is increasing. Compared to
conventional brush motors, inverter
motors are characterised by a
particularly high degree of efficiency at
low energy requirements. For instance,
an inverter motor only needs 12 W for
200 m³/h. That equates to around 10%
of the energy consumed by a standard
motor. Savings of up to 50% can be
achieved at the maximum setting (not
the intensive setting).
66
BMEECH13LL146002_Pages.indd 66-67
For example, at ventilation performance
of 700 m³/h, an inverter motor requires
only 150 W, compared to 250 W for a
standard motor. The motor electronics
(speed electronics) allow the motor
speed to be adjusted to any required
level while simultaneously using only a
low amount of energy. This provides
consistent performance over the entire
adjustment range, which allows high
ventilation performance at lower noise
values than those associated with
conventional motors.
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13.11.13 17:18
APPLIANCE SELECTION Surface extraction or edge extraction
Surface extraction or edge
extraction
Surface extraction
Surface extraction is the most well
known and most common form of
extraction used in cooker hoods. The
vapours generated when cooking are
extracted across large parts or the
entire surface of the vapour screen
and conveyed through the immediately
adjoining grease filter(s). This design is
68
BMEECH13LL146002_Pages.indd 68-69
characterised by particularly good
extraction of vapours at the centre of
the cooker hood and is recommended
when using cookware that creates a
particularly large amount of vapour
(see chapter "Information on woks,
deep fat fryers, grill pans and similar",
page 25).
Surface extraction or edge extraction APPLIANCE SELECTION
Edge extraction
Edge extraction is a more recent
variant among cooker hoods and is
often considered to be more
aesthetically appealing. In this design,
the grease filters above the hob are
covered by a glass or metal panel. The
rising vapours are extracted only at the
edge of the cooker hood through a
gap (or several gaps) between the
panel and the cooker hood housing
and then passed through the grease
filter(s). This design offers high airflow
speeds around the gaps of the cooker
hood. As a result, extraction is highly
effective, especially if the vapours are
generated towards the edge of the
hob, and the cooker hood can be
operated very effectively at lower
power settings. The hood also creates
a kind of suction curtain that prevents
vapours from escaping to the side.
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13.11.13 17:18
APPLIANCE SELECTION Filter types
Filter types APPLIANCE SELECTION
Grease filter
All cooker hoods are fitted with grease
filters. These are designed to trap the
grease particles contained in the
vapour when air passes through the
filter.
The grease is filtered out of the vapour
to protect both the kitchen and the
cooker hood itself (particularly the
motor and ducting) from grease
deposits.
When new or kept in a properly cleaned
condition, all grease filters are nonflammable or fire retardant and selfextinguishing.
The ability of a filter to capture grease is
limited. Depending on the filter type,
grease filters must therefore be
replaced (disposable filters) or cleaned
(reusable filters). This is required to
prevent the formation of undesirable
and unhygienic grease deposits and
also to minimise the risk of a grease fire.
Some appliances automatically indicate
when it is time to clean or replace the
filter via a saturation display. Filter
thickness also plays a role.
The thicker the grease filter, the greater
the air resistance and the lower the
suction effect. This reduces the
ventilation performance and usually
increases the hood noise level. Hoods
with a high suction force need filters of
a certain thickness to prevent the
grease from being sucked through the
filter. The optimum thickness and thus
the grease absorption capacity and
efficiency of a grease filter are therefore
determined by carefully matching the
fan type with an acceptable level of
noise.
Comparison of filter types and their characteristics:
Filter type
Filter
Grease
efficiency absorption
capacity
Washable
Service life, Noise
appearance
Fleece filter
tt
tt
–
t
t
Aluminium
mesh filter*
tttt
ttt
tttt
ttt
tt
Stainless steel
mesh filter*
tttt
ttt
tttt
tttt
tt
Stainless steel
fin/labyrinth
filter (baffle
filter)
tttt
ttttt
ttttt
ttttt
tttt
BMEECH13LL146002_Pages.indd 70-71
polyester (fleece thickness approx. 1
mm) or from approx. 5 mm thick
synthetic material such as acrylic or
polyester. Filters usually need to be cut
to size. It is advisable to change the filter
once a month. Some fleeces become
very discoloured when they need
changing. Observe the notes in the
relevant operating instructions.
Metal grease filters/mesh filters (made from aluminium and/or stainless steel)
These are permanent filters that can be
used for years without restrictions if
properly cared for.
Depending on its construction, a mesh
filter can consist of between 4 and 19
aluminium or stainless steel mats in a
filter frame. Metal filters need regular
cleaning — this can be between 15 and
100 hours of operation depending on
the model, but at the latest when the
noise starts to get louder. Cooker
hoods with a saturation display (based
on hours of operation) remind the user
when cleaning is due. A metal grease
filter can be soaked and cleaned by
hand. However, it is usually easier to
clean them in the dishwasher. Setting:
Intensive programme (60–70°C). To
prevent any dirt entering the mesh from
other crockery and becoming trapped,
mesh filters should be cleaned in the
dishwasher by themselves.
Holding frame
tttttWFSZHPPEUPtBEFRVBUFNFUBMHSFBTFGJMUFS
70
Fleece filters
These are disposable filters that must
be discarded and replaced when
saturated. They are not washable. The
fleece is usually made from cellulose or
Metal mesh
Meshed metal baffle
Metal mesh
Holding frame
Grease filter with
metal mesh
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APPLIANCE SELECTION Filter types
Aluminium grease filters may discolour
to light grey or take on a matt
appearance due to the effects of
aggressive, acid components in the
grease particles or aggressive
components in dishwasher detergent.
This does not, however, have an impact
on the filter's efficiency. Some designs
have filter mats with perforated stainless
steel covers. The grease in filters that
Filter types APPLIANCE SELECTION
are not cleaned for extended periods
can resinify and will not be removed
during cleaning. In such cases the filter
will have to be replaced.
Filters are held in place on the cooker
hood by various fastening mechanisms.
Magnetic strips are particularly good at
preventing cooking vapours from
escaping unfiltered.
Fin filters/labyrinth filters (baffle filters)
These are particularly effective and
durable permanent filters. They
comprise a labyrinth of channels with
stainless steel walls. Air can be filtered
FAN MOTOR
through these channels as particularly
high speeds. The air impacts against
the metal walls of the labyrinth at each
bend/loop and the forced change in
direction causes grease to be
deposited.
Labyrinth filters should be cleaned in
the same way as mesh filter: either by
hand or using the intensive programme
(65–70°C) in a dishwasher without other
crockery. As these filters are made
entirely of stainless steel, they will not
discolour like aluminium filters.
Odour filter - active carbon filter
Odour filters are required only for
cooker hoods that recirculate the air.
They are not necessary for extraction
hoods as the vapours containing the
odour are transported outdoors.
In an activated carbon filter, odorants
are captured on the surface of the
carbon (adsorbed). To enable the
maximum amount of odorants to be
filtered out, the carbon surface must be
very large. The carbon particles achieve
this through a combination of their small
size (diameter of 3–4 mm) and the fact
that they are porous or riddled with
narrow channels. This means that just 8
g of activated carbon granules has the
same surface area as a football pitch.
The flow speed of the air must,
however, not be too high. The fan and
filter type used in cooker hoods must
therefore be carefully matched. The
high absorption rate can only be
achieved if the active carbon filter is
replaced/cleaned on a regular basis.
This process is supported by a
saturation display that reminds users to
clean the filter at regular intervals.
The grease filter (typically installed
upstream of the active carbon filter)
must also function correctly. Any grease
particles that enter the activated carbon
filter are deposited, which blocks the
channels in the carbon pellets and
significantly impairs the odour filter's
function. It is therefore necessary to
carefully change and clean both filters
on a regular basis to ensure that the
cooker hood operates correctly.
Active carbon filters are available as
disposable versions or as reusable
versions (washable/regenerative) for
selected cooker hoods.
Regenerative filters are also referred to
as long-life filters.
Comparison:
HOB
Warning These filters are heavier than
conventional metal grease filters. This
must be taken into consideration when
removing them.
Type of activated carbon
filter
Performance
Filter efficiency,
cost effectiveness
Service life
Cost
Disposable
ttttt
tttt
tt
t
Regenerative/
washable
ttttt
ttttt
ttttt
ttt
tttttWFSZHPPEUPtBEFRVBUF
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APPLIANCE SELECTION Filter types
Disposable active carbon filters
This type of filter cannot be washed.
Disposable active carbon filters should
be replaced approx. every 4 months or
after 120–200 hours of operation,
depending on the type of cooker hood.
Refer to the operating instructions for
further details.
In disposable active carbon filters, the
carbon particles are loosely distributed
and contained in a paper sleeve inside
a round or rectangular filter cassette.
With filter cassettes in which the
particles can move around, ensure that
the particles are evenly distributed
before the cassette is inserted into the
filter. This will ensure that odorous
vapours come into contact with a
similar number of carbon particles at
any given point across the filter surface.
Reusable active carbon filters —
washable/regenerative active
carbon filters
Reusable active carbon filters can be
regenerated and reused 5–6 times
before they need to be replaced. They
must be regenerated after about 160
operating hours or every 2–3 months,
depending on the type of cooking.
In reusable filters, the carbon particles
are held in place in polyurethane. This
ensures that the same level of
performance if provided across the
entire filter.
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Lighting, Controls APPLIANCE SELECTION
Regenerating a reusable filter usually
involves two stages. First, the filter is
placed in a dishwasher and cleaned
using an intensive programme (60°C,
no other dishes!). It is then left to dry in
the air or in a preheated oven. Refer to
the operating instructions for further
details. Although regeneration
significantly improves the adsorption
capacity of a reusable activated carbon
filter, it is not possible to restore the
original level of performance. The
expected service life is approx. 3–4
years depending on the individual filter
and its use.
Lighting
Most cooker hoods are equipped with
halogen lamps (between 20 and 40 W)
to illuminate the hob. Energy-saving
lamps (9 to 11 W) are also used.
The use of LED lamps is interesting
from an energy-saving viewpoint and is
on the rise overall. These lamps
consume around 2.5 W each.
Reusable black coal filters are
regenerated by heating them in the
oven (service life approx. 5 years).
Tips for using and operating a
cooker hood:
− The cooker hood should be switched
on a few minutes before starting to
cook so that the air in the kitchen
starts to move in good time.
− Once cooking is finished, the fan
should be left to run for 10 minutes so
that odours in the room can continue
to be absorbed and the active carbon
filter can dry out.
− Kitchens with a recirculation hood
should be aired after cooking to
remove moisture from the room.
Benefits of LED lights vs. normal lamps.
Low energy consumption
- Reduction of energy
consumption up to 70%
Sustainability
- No use of quicksliver, sodium,
plumb or other heavy metals.
- Reduction of air pollution and
heatgeneration.
Good life expectancy
- Life expectancy of 50,000 hours/
10 years.
- Reduction of maintenance cost
Operation
Each cooker hood is equipped with
controls to regulate the power output.
These controls can be buttons, but the
use of touch operation and slide
controls is on the rise.
Cooker hoods with temperature and
humidity sensors regulate the power
setting automatically depending on
vapour development.
Some cooker hoods are available with
a remote control, which can be helpful
for shorter people or wheelchair users.
Recent developments include hoods
that can be operated via an infra-red
signal directly from the hob.
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Noise levels APPLIANCE SELECTION
APPLIANCE SELECTION Ventilation performance in accordance with standard
Ventilation performance/airflow
rate in accordance with
IEC 61591/EN60704-3
Electrolux measures the airflow rate of
cooker hoods (performance data)
exclusively in accordance with the
international IEC 61591 standard. The
measurement set-up specified in this
standard is based on commonly
available extractor ducting arranged to
provide a counter pressure of 15 or 30
Pascal at an airflow rate of 200 m3/h.
In practice, this corresponds to:
– A straight duct length of around 4 m
or
– A run of extractor ducting comprising
a vertical 30 cm section (from the fan
outlet upwards), a 90° bend and a
horizontal section of 1 m.
The "free-blowing" value that is often
provided as an alternative is of less use
to the consumer as it does not apply to
practical use. To obtain this value, the
measurement sensor is placed directly
at the fan outlet and the ducting is not
taken into account.
EMISSION
SOUND POWER DB (A) RE 1 PW
IMISSION
SOUND PRESSURE DB (A)
TIP
When comparing different cooker hood
brands, it is important to note whether
the performance data listed is stated as
"free-blowing" or "in accordance with
IEC 61591" or EN60704-3.
MEASUREMENT SET-UP (BASED ON STANDARD)
1000 mm
300 mm
Noise levels
Noise is generated by pressure waves
that are emitted by an acoustic source,
travel through the air at a speed of
around 333 m/s and are registered as
sound in the human ear. What a person
hears is actually acoustic pressure. The
acoustic source (the cooker hood, in
this case) emits the acoustic or sound
power.
Both of these values can be measured
and are indicated as:
– Sound pressure level in dB (A)
– Sound power level in dB (A) re 1 pW
The sound pressure level refers to the
volume at a certain distance (e.g. 1 m)
from the source of the noise
(immission). Since the sound pressure
level is dependent on the measuring
conditions (distance, reverberance and
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BMEECH13LL146002_Pages.indd 76-77
size of the room, etc.) and can be
compared only under identical
measuring conditions, it is not suitable
for providing comparative noise
information. Sound pressure is
indicated in dB (A) (decibels, A
weighting).
The sound power level refers to the
volume that originates (is emitted)
directly from the acoustic source. Since
it is measured directly at the source of
the noise, this measurement can be
standardised more easily and the
values are better suited for comparison
purposes. Sound power is indicated in
dB (re 1 pW) (decibels, relative
reference level 1 picowatt). The
standardised procedures for measuring
sound power are described in
international standard IEC 60704-3.
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APPLIANCE SELECTION Noise levels
APPLIANCE SELECTION
The sound power level of cooker hoods
is dependent on the selected power
level and lies between
40 and 70 dB (A) re 1 pW.
information about creating low-noise
extractor duct layouts when planning
the ducting (see chapter "Information
on exhaust air ducting", page 35).
Manufacturers of cooker hoods take
various measures to keep the noise
level as low as possible. For instance,
inverter motors are used or drive units
are mounted on bearings such that
their oscillations and vibrations are
transferred to the appliance in
weakened form. Installing noiseabsorbing mats can also help keep the
noise levels low.
Designs of
cooker hoods
TIP
– Any noise level specifications that
appears to be too low should be
queried in detail. What measurement
methodology has been used? Are the
values dB (A) or dB (A) re 1 pW?
– Performing a subjective comparison
"by ear" is only advisable if the
appliances are located directly
alongside each other. Otherwise, the
effects of the room acoustics will be
too great and a comparison may lead
to the wrong conclusion.
Airflow noises in the extractor ducting
have a stronger impact on noise levels
than the cooker hood itself. It is
therefore very important to observe
SOUND POWER OF DIFFERENT NOISE SOURCES
Fridge-freezer
Setting 1
Cooker hood
in extraction
mode
Helicopter
Intensive setting
Cooker hood in
extraction mode
Power saw
Washing machine
during spin cycle
10
20
0
30
Dishwasher
40
50
60
Washing
machine
during
wash cycle
Whisper
70
80
90
dB (A) re 1 pW
100 110
0 120 130
Loud speech,
lively children
Pneumatic
drill
Conversational
speech, typewriter
Consumers can choose from many different cooker
hood designs and widths to suit their kitchen.
All values are examples. Values may differ depending on the appliance.
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APPLIANCE SELECTION Island hoods chimney hoods
Island hoods
These decorative cooker hoods made
from stainless steel, and glass in some
cases, are used in modern kitchens
Wall hoods
with a cooking island. Island hoods
provide either surface or edge
extraction and are mainly available in
widths of 60, 90, 100 and 120 cm.
Island hoods are mounted to the
ceiling. Telescopic flues allow these
hoods to be used in different room
heights. The exhaust air can be routed
through the ceiling or through a lateral
extractor duct. When selecting an
island hood, it is important to keep an
eye on overall proportions in the
kitchen. Above all, it should not interrupt
the view of the living/dining area.
Chimney hoods
This type of hood is decorative and is
used if the hob is located in front of a
wall. Chimney hoods are made from
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Wall hoods APPLIANCE SELECTION
Wall hoods are used if the hob is
located against a wall. They are fitted
with almost vertical or diagonal surface
or edge extraction units and the
vapours are extracted upwards/
backwards. Wall hoods are mainly
available in widths of 55, 60, 80 and 90
cm. The range of different designs
makes them particularly decorative.
Wall hood with edge extraction
In this version, the grease filters are
covered by panels made from stainless
steel or glass. The rising vapour is
sucked into gaps between the panels
and conveyed to the grease filter behind
the panels.
Wall hood with surface extraction
and covered grease filters
In this version, the grease filters are
covered by a sealed glass plate. The
glass plate opens forwards/upwards
when using the hood. This creates a
vapour trap behind the plate and in front
of the inclined grease filters.
Wall hood with surface extraction
and visible grease filters
The grease filters on this design variant
(e.g. labyrinth filters) are clearly visible
(see chapter "Grease filters", page 61).
stainless steel, and glass in some
cases, and are available in a range of
sizes and styles. They all provide either
surface or edge extraction and are
mainly available in widths of 60, 90 and
120 cm. The exhaust air can be routed
through the wall behind the hood or
through a lateral extractor duct.
Chimney hoods can be integrated as a
design element between two wall units
or placed freely on the wall.
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APPLIANCE SELECTION Ceiling extractors worktop extractors/hob extractors
Ceiling extractors
A ceiling extractor is a flat cooker hood
that is preferably installed directly above
the hob in a (suspended) ceiling. Ceiling
extractors are particularly suitable for
cooking islands, especially when an
unimpeded view of the living/dining area
is required. However, they also provide a
visual highlight when placed above other
cooking areas.
Ceiling extractors feature edge
extraction. Ceiling extractors are
primarily available in a width of 90 cm
with a recommended distance of up to
1500 mm, depending on the hood. They
are controlled via a remote control.
Worktop extractors/hob
extractors
Worktop extractors are built into the
worktop between or alongside the
hobs or hob modules. This type of
appliance extracts vapour downwards.
The extraction force creates a crossflow across the hob. This airflow sucks
in the vapours before they have a
chance to rise. It is important to install
the worktop extractor directly adjacent
to the hob.
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Retractable table-top hoods extractor modules APPLIANCE SELECTION
Retractable table-top hood
The new table-top hood design (width
60 or 90 cm) is built into the worktop
behind the hob and can sink into the
worktop. Instead of being extracted
upwards, vapour is drawn backwards
and downwards. The fan is located in
the floor cupboard. This type of
extractor uses edge extraction and its
high performance provides effective
and particularly quiet vapour extraction.
Retractable table-top hoods can be
used in cooking islands.
Extractor modules
Extractor modules are designed for
installation in individual cooker hoods or
flues made from wood, metal or brick
and offer a wide range of planning and
design options. Electrolux extractor
modules are made from stainless steel
and work on the principle of surface
extraction. They are available in widths
of 55, 56 and 80 cm.
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APPLIANCE SELECTION Built-in hoods
Conventional hoods APPLIANCE SELECTION
Built-in hoods
Conventional hoods
Build-in hoods are installed in a wall
unit. The exhaust ducting can be routed
through the ceiling or laterally along the
wall units. Built-in hoods allow for space
to be used to optimal benefit in the
kitchen.
Flat screen cooker hoods
This hood version is either completely
hidden in a wall unit or installed so that
only the narrow stainless steel bar of
the vapour shield can be seen beneath
the wall unit. Before this cooker hood
can be used, the vapour shield must be
extended like a telescope so that it
covers the hob area. Flat screen cooker
hoods provide surface extraction and
are available in widths of 60 and 90 cm.
Owing to the small space requirement
of this cooker hood, part of the wall unit
can still be used for storage, e.g. as a
spice cabinet.
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Conventional hoods are used either
beneath a thin wall unit or mounted
directly to the wall above the hob. When
mounted on the wall, a conventional
hood can be combined with a flue fixture
(stainless steel telescopic flue). This
provides a kitchen appearance. These
hoods provide surface extraction and
are available in widths of 50 and 60 cm.
Integrated hood (built-in hood
behind a cabinet door)
These cooker hoods fill an entire wall
unit (width: 56 cm) or are installed
between two wall units (width: 60 cm)
and fitted with a fold-out cabinet door
or stainless steel front. The hood
cannot be seen when closed. The front
plate opens forwards/upwards when
using the hood. This creates a vapour
trap behind the plate and in front of the
inclined grease filters. The vapours are
extracted using surface extraction.
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APPLIANCE SELECTION At a glance
AT A GLANCE
– Centrifugal fans are the main
choice of fan for cooker hoods.
– Inverter motors in cooker hoods
achieve comparatively high
ventilation performance with up to
50% less energy.
– Surface extraction units are
characterised by very efficient
suction at the centre of the cooker
hood.
– Edge extraction units are often
considered to be visually attractive
and are characterised by high
airflow speeds. This is especially
beneficial when the hob and the
hood are of the same width.
– Grease filters are key to the
functionality of a cooker hood.
Saturation displays (operating hour
counters) indicate when cleaning is
due. Metal grease filters are easy to
clean. Stainless steel filters in
particular are visually appealing
and do not discolour when cleaned
in the dishwasher.
– There are many different designs
and styles on the market to cater
for personal preferences and room
conditions.
– Many cooker hoods are now
equipped with energy-saving LED
lamps.
– Some cooker hoods offer remote
or hob-based controls in addition
to buttons or touch controls.
– The hood's ventilation performance
should be stated in accordance
with the appropriate standard.
When comparing hoods, pay
attention to whether the rate is
stated in accordance with the
standard or as "free-blowing".
– The noise produced by a cooker
hood depends on its motor and
noise insulation. It can be
expressed as a sound power rating
dB (A) re 1 pW or sound pressure
rating dB (A). The power rating
should also be taken into
consideration when comparing
cooker hoods.
– Odour filters are made of active
carbon that binds and retains
odorous substances. These active
carbon filters must be changed on
a regular basis. Some odour filters
are washable and therefore have a
longer service life.
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INDEX
INDEX
Index
A
Exhaust air
Exhaust ducting
B
Operation
Comfort curve
Lighting
Operating modes
Operating hours counter
D
Ceiling extractors
E
Built-in hoods
Energy-efficient houses
16, 34, 54
39, 61
75, 86
12
75
16, 34
71, 86
82
84
11, 35, 61
K
Chimney hoods
Chimneys
Characteristic curve
Active carbon filters
Condensation trap
L
Labyrinth filters
Fin filters
Air exchange
Extractor modules
Airflow rate
Ventilation
performance
Ventilation systems
Air exchange rate
80
58
40, 46, 48
65, 73, 86
49
70, 72
72
10, 22 54
83
20, 53, 76
20, 42, 76, 86
10
20
F
Solids
13
Grease
12, 22, 70
Grease filters
65, 70, 86
Moisture
11, 22
German Ordinance on Combustion
Equipment (FeuVO)
59
Surface extraction
65, 68, 86
Flat screen cooker hoods
84
M
Wall vents
16, 50, 60
Exhaust/intake air wall vents
50, 59
Metal filters
22, 71
Worktop extractors/hob
extractors
82
G
Gas hobs
Noise levels
Odour filters
Odorous substances
P
Passive houses
Planning
H
Domestic ventilation systems
I
Island hoods
Inverter motor
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31, 61
65, 77
73, 86
12, 73, 86
36
28, 80
67, 86
N
Low-energy houses
Q
Air cross-flow
35, 62
S
Saturation displays
Sound pressure level
Sound power level
Safety distances
Airflow speeds
T
Telescopic flues
Temperature and
humidity sensors
U
Recirculation
Recirculating mode
Conventional hoods
V
Retractable table-top hoods
Fleece filters
W
Wall hoods
Heat
Vapours
Z
Auxiliary fans
Integrated hoods
71, 86
77
77
29
69, 86
80
75
16, 37
17, 22, 34
85
83
71
28, 81
12, 36
11
46
84
35
27
20, 28, 82
R
Centrifugal fans
67, 86
Edge extraction
68, 86
Room climate
11
Ambient air heating appliances
59
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