Operation of split air conditioning systems with

Operation of split air conditioning systems with
Proklima International
Operation of split air conditioning
systems with hydrocarbon refrigerant
A conversion guide for technicians, trainers and
engineers
Imprint
Published by:
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
– German International Cooperation –
Programme Proklima
Dag-Hammarskjöld-Weg 1-5
65760 Eschborn, Germany
Internet: www.giz.de/proklima
Programme manager: Bernhard Siegele
Contact: [email protected]
On behalf of:
Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)
Programmbüro Internationale Klimaschutzinitiative
Potsdamer Platz 10
10785 Berlin
E-Mail: [email protected]
Phone: +49 (0)30 408 190 - 218
Fax: +49 (0)30 408 190 – 303
Internet: http://www.international-climate-initiative.com
Lead authors:
Dr Daniel Colbourne, Rolf Hühren
Other contributor:
Linda Ederberg
Peer reviewer:
Manuel Azucena, Philippines - Trainer, HPMP consultant
Editor:
Rebecca Kirch
Design:
Jeanette Geppert, www.jeanette-geppert.de
Eschborn, October 2011
2
Operation of split air conditioning
systems with hydrocarbon refrigerant
A conversion guide for technicians, trainers and
engineers
3
PROKLIMA is a programme of the Deutsche Gesellschaft für
Internationale Zusammenarbeit (GIZ) GmbH. Since 2008 Proklima has
been working successfully on behalf of the Federal Ministry for the
Environment, Nature Conservation and Nuclear Safety (BMU) under its
International Climate Initiative (ICI) to disseminate ozone-and climatefriendly technologies.
PROKLIMA has been providing technical and financial support for
developing countries since 1996, commissioned by the German Federal
Ministry for Economic Cooperation and Development (BMZ) to
implement the provisions of the Montreal Protocol on Substances that
Deplete the Ozone Layer.
4
Disclaimer
Whilst GIZ does not condone the conversion of existing equipment using
non-flammable refrigerant to use flammable refrigerants that they were not
initially intended for, we do recognise that such conversion do and will
continue to take place, regardless of recommendations to the contrary.
Therefore, in order to try to help that it is done in the safest manner this
booklet was developed.
However, in doing this, GIZ does not assume liability for any statements
or any actions taken by its readers or users, which may cause unintended
damage or injury as a result of any recommendations or inferences made
within this handbook. Although all statements and information contained
herein are believed to be accurate and reliable, they are presented without
guarantee or warranty of any kind, expressed or implied. Information
provided herein does not relieve reader or user from their responsibility of
carrying out its own evaluation and analysis of the situation, and readers or
users assume all risks and liability for use of the information, actions and
events obtained. Readers or users should not assume that all safety data,
measures and guidance are indicated herein or that other measures may not
be required.
Here only general recommendations are made, which do not compensate
for individual guidance and instructions.
National laws and guidelines must be consulted and adhered to under all
circumstances. The handling of flammable refrigerants and its associated
systems and equipment is to be done by qualified and trained technicians
only.
5
INTRODUCTION
There are currently about 1 billion hydrochlorofluorocarbons (HCFCs)
room air conditioners in operation worldwide, more than 100 million units
are added annually (still with double digit growth rates due to higher
demand). Each unit contains on average 1.6 kg of refrigerant, mainly R22.
The Global Warming Potential (GWP) of R22 is 1810, amounting to
almost 3,000 MT CO2 equivalent of emissions. Servicing needs amount to
annually 800,000 T R22, equal to about 1450 MT CO2 equivalent per year.
In response to the environmental impacts – primarily ozone depletion and
global warming associated – arising from the release of HCFC and
hydrofluorocarbons (HFCs), the use of natural refrigerants as alternatives to
these is becoming more widespread. Amongst these natural refrigerants,
hydrocarbons are being used widely in new air conditioning systems.
Under certain circumstances, there may be a desire to convert a refrigeration
and air conditioning (RAC) system from a non-flammable refrigerant to use
hydrocarbons (HCs). This approach may be considered for a number of
reasons, such as:
•
•
•
•
An intention to improve the efficiency of a system
To minimise the environmental impact
Because it may be more cost-effective than using other refrigerant options
There are no other refrigerant replacements available
Refrigerants that may be used for such purposes could include R290
(propane) or R1290 (propylene), where, for example, the system was
previously charged with R22 or R407C.
Of course, if the existing refrigeration system is working correctly, then
there is normally no need to convert the system to use any alternative
refrigerant.
These guidelines are intended to assist with the safe conversion of air
conditioning systems to use flammable HC refrigerants. Converting a
system from an HCFC to an HFC normally requires basic changes.
However, converting a system from a non-flammable to a flammable
refrigerant requires special considerations, which are summarised here.
6
BASIC PRINCIPLES AND WARNINGS
When applying a flammable refrigerant to a system that ordinarily uses a
non-flammable refrigerant, the term “conversion” is applied. This is important as it distinguishes from other phrases such as “re-fill”, “drop-in” and
“retrofit”. The reason for this is that when a non-flammable refrigerant (such
as R12) is replaced by another non-flammable refrigerant (such as R134a), if
any changes are required to the system, then they relate to performance
(e.g., change of capillary tube length) or compatibility (e.g., change in oil
type). However, when changing from a non-flammable refrigerant (such as
R22) to a HC refrigerant (such as R290), additional considerations must be
taken into account. These include identifying whether or not the HC can be
applied given the particular circumstances from a safety perspective, and if
so, carrying out the required changes to the equipment that are related to
mitigating the flammability risk. A switch from a non-flammable to a
flammable refrigerant should be considered in terms of an entire conversion
of the equipment, not just a change of refrigerant.
It must be emphasised that carrying out a system conversion to use flammable refrigerant necessitates careful consideration of the implications and it is
essential to weigh up the risks and benefits. If a conversion is to take place,
then it should be done comprehensively, with care and with attention to
detail.
Given that a conversion to a flammable refrigerant represents a significant
change in the purpose of the system, it must be understood that the
conversion can only take place provided that the final product meets the
requirements of the relevant safety standards and national regulations.
7
SPECIAL INSTRUCTIONS
• Any technician involved with conversion must be fully trained, competent
and certified to use this flammable refrigerant
• Only convert with permission of building owner
• Only use proper service equipment suitable for use with HC refrigerants
• Multi-split and ducted systems which use large refrigerant charges are
not suitable for conversion to HC refrigerants
• Refrigeration systems with extensive pipe work and multiple evaporators,
such as compound plants, are not suitable for conversions
• If the situation permits, it is recommended that the equipment is
removed from its existing position to a controlled workshop environment
where work can usually be conducted in a more controlled and safer
manner
CONSIDERATIONS AFFECTING CONVERSIONS
When approaching the choice of converting a particular system, it is
important to follow a logical sequence of safety-related considerations to
help make the correct decision. Such considerations include the following
issues:
•
•
•
•
•
•
The type and complexity of the equipment to be modified
The environment and location within which the equipment is installed
The quantities of refrigerant involved (in relation to the system location)
The ease or possibility of modifying parts of the system
The ease or possibility of handling the potential sources of ignition
The necessity to develop specific awareness for the system operation by the
owner
A decision chart to assist with evaluating the suitability of the equipment
(predominantly with respect to the requirements of the safety standards) is
shown in Table 1. This may be used to provide a good indication as to
whether a system can be converted to use an HC refrigerant, although other
specific aspects may need to be considered in addition; i.e., the requirements
elsewhere within this guidebook (for new systems) and the relevant safety
standards.
Since the refrigerant charge and the location of the refrigerant-containing
parts of the system have such a strong influence on whether or not a
conversion is viable (from a safety point-of-view), the suitability can be
approximated according to typical system types. Table 1 provides an
8
indicative overview of the types of systems that have been found to be
acceptable for conversion. The viability is indicated as follows:
✔✔
✔
✘
✘✘
often suitable
sometimes suitable
normally unsuitable
nearly always unsuitable
As previously explained, each situation is unique in terms of the combination of system design and installation location and therefore each must be
evaluated independently.
Table 1: Typical suitability for conversion of systems to use hydrocarbons
Sector
Equipment type
System type
Domestic air
conditioners,
dehumidifiers
and heat pumps
Portable units
Integral
✔✔
Window units
Integral
✔✔
Through-wall units
Integral
✔
Split units
Remote
✔✔
Split units
Remote
✔✔
Multi-split/VRV
Distributed
Packaged ducted
Remote
✘
Central packaged
Remote
✘✘
Positive displace chillers
Integral/Indirect
✔✔
Centrifugal chillers
Integral/Indirect
✘✘
Commercial air
conditioning and
heat pumps
Suitability
✘✘
Two other issues should be considered with respect to carrying out a
conversion.
Firstly, it is strongly recommended that companies set up special conversion
workshops, policies and upgrades of tools and equipment at their facilities.
Thereby, systems can be removed from the site to the dedicated workshop in
order to carry out conversions. There are significant advantages to this:
9
• Access to proper tooling and equipment is more likely
• The working area can be set up to handle the use of flammable refrigerants
• Preparation activities for commissioning with HC will minimise handling
at installation site
• Expert technicians that specialise on HCs are more likely to be present
• There will be better and more immediate access to the required parts and
components
Whilst it is understood that certain types of equipment may not be
portable, this approach should be taken if it is possible.
Secondly, companies involved in frequent conversions of a particular type of
system should prepare “conversion kits” for their technicians, where each kit
is dedicated to a particular type of RAC system. When approaching the
choice of converting a particular system, it is important to follow a logical
sequence of safety-related considerations to help make the correct decision
as to whether it is possible to convert the system or not. The decision chart
in Figure 1 must be used to assist with evaluating the suitability of the
equipment to use HCs.
10
Figure 1: Decision chart for determining whether it is possible to convert a system to
HC refrigerant
11
CONVERSION KITS
If enterprises are involved with carrying out conversions of existing systems,
it is recommended that “conversion kits” are used. The reason for this is that
it can be “inconvenient” for technicians – once at a site and already working
on a system – to avoid using unsuitable methods for the conversion to HC
refrigerants, which of course should be avoided. One way of helping to
implement appropriate conversion methods is to issue technicians with a
comprehensive conversion kit that contains all the necessary tools and parts.
For example, such kits shall contain data sheets (with conversion factors,
room size/charge size estimations, etc.), risk assessment forms, working
instructions, sealed and solid-state electrical components, flammable gas
stickers, valves, special fittings, and so on. If enterprises typically deal with a
range of different systems, then it is sensible to have conversion kits that are
better suited to each different type of system. Besides specific (if requested)
fan motors, pressure switches, capacitor, overload protectors, etcetera, are
needed. An example of a conversion kit is shown in Table 2.
Table 2: Example of a standard conversion kit collection for small AC systems
Set of blade connectors,
ring and spade terminals
etc.
Specific tools for
connectors fixing
Sealed box, size depending
the components to be
inserted (usually the mains
contactor) together with
fastening screws
12
Different type of screwed
cable glands
Mains contactor according
to the capacity required if
replacement of existing
device is indicated
Flexible electric cable
(wiring diameter according
capacity of the system)
Different cable straps for
the fixation of wires and
cables and not intended for
tubes fixing
13
Electrical tape
Commissioning report,
conversion label and
warning sign stickers
(see also annex of this
document)
CONDUCTING CONVERSIONS
When carrying out a conversion, the correct sequence of activities must be
done in a way that both the safety of the workplace is maintained as well as
ensuring the safety of the equipment. A process is provided in the flow chart
in Figure 2.
14
Figure 2: Flow chart indicating the sequence of activities for converting a system to
use HC refrigerant
15
The following steps describe the process in Figure 2 and describe the
important stages in evaluating and carrying out those conversions.
Estimate the required HC refrigerant charge size
This can be done using the existing refrigerant charge. Obtain the current
refrigerant type and charge size from the equipment data-plate and / or
verifying the existing amount of “old” refrigerant during the recovery
process. Using the chart in Figure 3, estimate the equivalent mass of HC
refrigerant.
Existing refrigerant charge (kg)
Figure 3: Conversion to estimate equivalent HC charge size
HC refrigerant charge (kg)
!
Check the refrigerant charge will be permissible
Ensure that the quantity of HC refrigerant to be used is permitted within
the given room size. Calculate the occupied room area for the indoor unit
and compare it with the HC charge size (Figure 4). For further information
refer to GIZ-Proklima publication “Guidelines for the safe use of hydrocarbon refrigerants”, Section 5.3 “Refrigerant charge size limits”.
16
Maximum HC charge (kg)
Figure 4: Minimum room sizes for a given refrigerant charge for air conditioners for
human comfort (above) and air conditioning not for human comfort (below)
wall/ceiling
unit
floor unit
Maximum HC charge (kg)
Room floor area (m2)
Room floor area (m2)
17
Check all necessary tools present
Prior to carrying out any work, it is essential to ensure all the tools,
equipment, instrument and spare parts required for the work are on hands.
In particular, this includes:
• General hand-tools appropriate for
the use at refrigerant circuit
components and electrics
• Refrigerant recovery machine
(suitable for use with flammable
refrigerants)
• Refrigerant recovery cylinder (two
valves) HCFC
• Refrigerant recovery cylinder (two
valves) HC (if it is decided to
recover the HC refrigerant)
• Lubricant recovery cylinder (two
valves)
• Refrigerant venting hose
• Comparator/pressure-temperature
tables for HC refrigerant
• Vacuum pump
• Vacuum gauge (electronic) refrigerant balance (accuracy of at least
±3% full-scale)
• Handheld HC refrigerant gas
detector
• Nitrogen service cylinder set
• Brazing set (oxygen/propane,
oxygen/acetylene)
• Flammable gas (yellow triangle)
stickers
• Flammable refrigerant warning
signs
• Work area warning signs
• Safety gloves and goggles
• Fire extinguisher
The list comprises of both, equipment for work on HCFC and HC
refrigerants.
Check the working area and system
Ensure both the working area and the system is safe. This includes:
• All staff, maintenance staff and others working in the local area must be
instructed that flammable refrigerants are being handled
• The area around the workspace must be sectioned off
• Working within confined spaces should be avoided
• No flammable materials are stored in the work area
• No ignition sources are present within a minimum of two metres anywhere
in the work area
• Suitable fire extinguishing equipment (CO2 or dry-powder type) is
available within the immediate area
• The work area is properly ventilated; ventilation should safely disperse any
released refrigerant
• HC gas detectors are present and operating to warn workers of a dangerous
concentration
• Erect appropriate signage, including “flammable gas”, “no naked flames”
and “do not enter the area”
18
• All appropriate and necessary tools and equipment are available
• The equipment should, whenever possible, be isolated from the electricity
supply
Figure 5: Designated work area where potential Sources of Ignition (SOI) must not be
present during service works
Indoor
Unit
Outdoor
Unit
2 Metres
Safty
Area
Initial leak check
Before removing the existing refrigerant, a leak check must be carried out.
Search for leakage on the high-side of the system (whilst the system is
operating) and on the low side (when the system is off). Use electronic gas
detector and soapy water, where appropriate. If any leak is found, this must
be repaired before conversion.
Access refrigerant circuit
Connect the refrigerant hose to service valve. The system must not be
broken into, by means of cutting, breaking or brazing pipework, if it
contains any flammable refrigerant or any other gas under pressure.
If it is necessary to break into a system, especially to change parts or to carry
out brazing, all of the refrigerant must be recovered from the system and
then flushed with nitrogen.
Recovery
Any remaining refrigerant within the system must be recovered, particularly
since the refrigerant is CFC, HCFC or HFC and therefore if released will be
19
harmful to the environment. Furthermore, there are also safety implications
associated with releasing non-flammable refrigerants. Therefore a recovery
machine should be used to recover the existing refrigerant, and stored in a
recovery cylinder approved for that refrigerant. Identify the existing
refrigerant type and quality in order to decide to recover for recycling or
destruction purpose. Identification may take place, taking the type of
refrigerant from the data plate, comparing with temperature / pressure
method or with the use of a quality identifier. Particular attention must be
paid to prevent mixing refrigerants and to avoid overfilling the cylinder.
Lastly, mark the cylinder appropriately after use.
Figure 6: Example testing the “old” existing HCFC R22 refrigerant quality
If recovering HC refrigerant, the recovery machine should be suitable for
use with flammable refrigerants.
Repairs to the system
It may be necessary to carry out repairs to the system. In this case, all
repairs must be completed before charging with HC refrigerant. If repairs to
the refrigerant circuit have been made, it is necessary to carry out a thorough leak check using pressurised nitrogen before proceeding.
20
At this point, it may also be beneficial to take the opportunity to conduct
other, less critical repairs, such as oil changes, replacing filter driers, internal
cleaning of the circuits, replacing damaged parts, and so on.
Design changes
The design changes that are made to the RAC system are critical to ensure
that the safety requirements are met. It is essential that, based on the system
type, location, occupancy and HC refrigerant charge size, the appropriate
safety features are integrated into the equipment. Failure to do this properly
may result in a serious flammability hazard. The major considerations are
usually:
• Elimination of all mechanical joints from occupied space and
minimisation of the possibility for leakage
• Elimination of all potential sources of ignition
• Setting up of emergency detection/ventilation/alarm system, where
applicable
• Application of relevant markings and modifications to instructions
It is re-emphasised that particular attention must be paid to addressing the
potential sources of ignition. In all cases the following assessment must be
carried out:
• Inspect the system and associated equipment, noting down all electrical
components
• Determine which of the components could act as a potential source of
ignition
• Decide how each of those potential sources of ignition will be handled, for
example:
- by replacing with sealed components
- using solid state devices or types
- placing within a fully sealed enclosure
- re-positioning outside the unit away from leaked refrigerant
• Consider also that electrical terminals and wiring connections must be
adequately secured and sufficient insulation is provided to avoid shorting
of parts
• Carry out the modifications accordingly
An example of aspects to look at is indicated in Figure 7.
21
Figure 7: Check for potential SOI sources and design changes, areas where
interventions can be necessary
Transformer,
display/ LED, swing
motors, fan motor,
connection on block,
PCB (relays, micro
switch)
Capacitors,
connection on block
Flared tube joints
within occupied space
Compressor terminals
(internal overload protector)
Fan motor
and capacitor
Tube flares at the
outdoor unit must be
of good condition
An example of options for modifying a potential source of ignition is
provided in Figure 8.
22
Figure 8: Example of how to prevent electrical contactor acting as a source of
ignition; “option A” is fitting the contactor within an sealed enclosure in its
existing location and “option B” is relocating the contactor outside the
housing within a separate enclosure
The marking of all equipment that contains HC refrigerant is also reemphasised here. The appropriate “flammable gas” stickers must be placed
on equipment housing entries and refrigerant access points, as well as on
exposed piping (Figure 9). This should also be supplemented by a comprehensive warning sign applied to an access panel to provide advice to other
technicians.
23
Figure 9: Appropriate warning sticker (left) and comprehensive warning sign (right) for
use of system access panels
)ODPPDEOH
JDV
Sealing the system
Upon completion of the work to the system, the circuit must be sealed
according to the guidelines. This means through either:
• Using compression (e.g., Lokring) connectors explain
• Brazing the service port (process tube) using pinch-off pliers
• Closing service valves
NOTE: The use of Schrader valves or line-tap valves should be generally
avoided. Schrader valves can leak if not properly sealed and caps can be
easily removed. Line-tap valves are for temporary use only (e.g. refrigerant
recovery) but must not be left on the system.
Testing the integrity of the system
If the refrigerant circuit has been broken into, it is necessary to carry out
leak tightness tests and strength pressure tests.
These may be carried out simultaneously by pressurising the system with
oxygen-free dry nitrogen to the maximum working pressure of the system
(plus 10%) and then check every single joint, connection and component
for bubbles using soapy water or other such fluids.
If a leak is identified, follow the appropriate procedures to repair it.
24
Evacuation
The system must be evacuated.
This requires a use of a suitable vacuum pump and electronic vacuum
pressure gauges; the system should maintain a vacuum of 200 microns, held
for at least 15 minutes (without the pressure changing).
Refrigerant charging1
Provided that the system is proved to be leak free, charge the quantity as
determined above. Charging must be carried out by mass using an electronic balance (accuracy of at least ±3% full-scale). Avoid charging to system
pressure/temperatures only.
Consider the following:
• Ensure there are no sources of ignition nearby
• Place an HC gas detector at floor level to warn of any inadvertent release
• When connecting hoses between the refrigeration system, manifold gauges
and refrigerant cylinder, ensure that the connections are secure
• Ensure that the refrigeration system is earthed prior to charging
• Extreme care must be taken not to overfill the refrigeration system
• After charging, carefully disconnect the hoses so to minimise the quantity
of refrigerant emitted
• The mass of refrigerant charged into the system should be noted in a
log-book and marked on a nameplate
When charging be aware that HC refrigerant have a lower density than
most other refrigerants; only 40 – 50% of the charge expected with HFC/
HCFC is needed. Remember that HC refrigerant blends must be charged in
liquid state.
1 A note on refrigerant purity: Refrigerant grade product should be used for all RAC systems.
Commercial grade HCs (e.g. liquefied petroleum gas, LPG) contains significant quantities of
sulphur, water, and other impurities and could contribute to oil degradation, shorten
compressor life and invalidate warranties. The composition of commercial LPG is variable so
the thermodynamic properties of the fluid may vary significantly from cylinder to cylinder.
Also, unlike commercial LPG, HC refrigerants are not odorised.
25
Final leak check
After charging with refrigerant, carry out leak tightness checks, using a
combination of:
• HC gas detectors – check every single joint, connection and component for
the presence of refrigerant
• Bubble test – check every single joint, connection and component is
checked for bubbles using soapy water or other such fluids
Search for leakage on the high-side of the system (whilst the system is
operating) and on the low side (when the system is off).
If a leak is identified, follow the appropriate procedures to repair it.
Systems may have more than one leak, so the system should be repeatedly
checked (including positions of recently repaired leaks).
Final checks
After charging and leak checking is complete, carry out final checks to
ensure a safety and reliability of the system:
• Repeat checks to electrical components (i.e., there are no potential sources
of ignition)
• Initiate the operation of the refrigeration machine and run the unit for a
period of about 15 – 30 minutes
• Check for correct operating pressures, temperatures and current
• Ensure sealing caps have been replaced
26
CONVERSION EXAMPLE FOR SPLIT AIR CONDITIONER
The following pictures provide an example of the various steps one may take
to convert a split air conditioner from R22 to R290.
Identify problem with air
conditioner
Proper operating RAC equipment generally
should not be converted to any other
refrigerant (do not touch a good running
system). Systems which may bear major
problems, such of corrosion of heat exchanger
and main frame or the system is overaged,
should not be subject for a conversion to HC
refrigerant.
Figure 10: Example of AC system that is
unsuitable for conversion
If the (R)AC system is in a generally good
condition and subject to any repair or service
where a breaking into the refrigerant circuit
is necessary (e.g. damaged compressor,
leaking system) considerations should be
taken to convert the system to a HC
refrigerant if safety considerations permit.
27
Assumption:
A fully functional system does not need to be converted. The only time when
a system may be converted is when there is a problem with the equipment
that at least requires handling of refrigerant and/or breaking into the
system.
AC split system conversion activities from HCFC R22 to HC R290
This example explains the conversion of an HCFC R22 based AC Split
system (2.8 kW / 9000 BTU – cooling only) after repairing a leaky suction
line coupler between indoor and outdoor unit, identified during system fault
finding procedure within the operational HCFC R22 system.
Step 1)
Obtain current charge size
-> 0.68 kg of R22
The charge size is
generally indicated with
the data plate.
If there is no information
available at the outdoorunit (e.g. weather-beaten)
check if there is
information available at
the indoor-unit.
Finally, the charge
amount can also be
estimated from the
amount of recovered
(old) HCFC refrigerant
charge amount (assuming
there was no leak
prevailing).
28
Figure 11: Split AC system data plate
Existing refrigerant charge (kg)
Step 2)
Estimate equivalent HC
charge
-> Conversion to R290,
R22 charge is 0.68 kg and
equivalent HC charge
according diagram (Figure
12) is 0.28 kg of HC R290
0.680 kg
0.280 kg
HC refrigerant charge (kg)
!
Figure
12: Refrigerant charge calculation
diagram
Step 3)
Identify occupancies
-> Outdoor unit is in well
ventilated area, and
general occupancy (category A) is above ground
level
-> Indoor unit within
office for human comfort
Figure 13: Example AC system installation
29
Maximum HC charge (kg)
Step 4)
Check charge size
limits
-> Charge size is below
maximum limit of 1.5 kg
(0.28 kg < 1.5 kg)
-> Room size is 6 m × 5 m
= 30 m2, so below
allowable charge (0.28 kg
< 0.48 kg)
wall/ceiling
unit
floor unit
0.480 kg
Room floor area (m2)
30m2
Figure 14: Maximum charge amount for
existing room size
Step 5)
Check all
necessary tools are
present and the working
area is safe
-> Okay
i)
ii)
iii)
iv)
v)
vi)
vii)
30
General hand-tools appropriate for the
use at refrigerant circuit components and
electrics
Refrigerant recovery machine intended
firstly for the HCFC R22 charge but
suitable for use with flammable
refrigerants (if subsequent service/repair
with HC R290 is necessary)
Refrigerant venting hose (only for venting
of small amounts of HC during service or
repair) and minimum of ½” OD
Refrigerant recovery cylinder (two
valves) for the existing R22
Lubricant recovery cylinder (two valves)
utilised in series between recovery unit
inlet and AC unit service port (oilseparator)
Comparator/pressure-temperature tables
for HC refrigerant (provided with the
annex of this document)
Vacuum pump with connector of the
venting hose at the exhaust port
Step 5)
viii) Vacuum gauge (electronic), to check the
200 micron vacuum level
ix) Electronic refrigerant balance (accuracy
of at least ±3% full-scale)
x) Handheld HC refrigerant gas detector
xi) Nitrogen service cylinder with pressure
regulator
xii) Brazing set (oxygen/propane)
xiii) Flammable gas (yellow triangle) stickers
xiv) Flammable refrigerant warning signs
xv) Work area warning signs
xvi) Safety gloves and goggles
xvii) Fire extinguisher
Further required the spare parts and HC R290
refrigerant.
NOTE!
Whenever possible the system must be
disconnected from power-supply!
Secure unintentional restarting of the system!
31
Step 6)
Eliminate all mechanical
joints from occupied space!
Figure 15: Mechanical connections in occupied space
In this specific case the
identified leaking coupler
within the suction line was
removed and therewith
the leak was repaired.
Before repair: Arrow indicates leaky flared
coupler within the suction line.
Figure 16: Removal of mechanical connections by
joining tubes with brazing
After repair: Both mechanical joints are
removed within the occupied space and doing
so, the identified leak (suction line coupler)
was repaired.
Figure 17: Joining tubes with Lokring couplers
32
Step 6)
-> Okay
Alternative repair: There where brazing is not
possible or as general alternative tube joining
method, pressing connection (Lokring) can be
used.
Figure 18: Lokring coupler for refrigerant transfer
tubes
Step 7)
Reset pressure
device -> Okay
Not applicable
33
Step 8)
Eliminate all potential
sources of ignition
Figure 19: Checking for SOI at the indoor unit
-> Inside unit:
transformer, display/ LED,
swing motors, fan motor,
connection block, PCB
(relays, micro switch) –
all non-SOIs
-> Okay
-> Outdoor unit: – fan
motor, capacitors,
connection block,
compressor terminals
(internal overload) – all
non-SOIs,
In general, wire connection screws must be
fastened and wires have to be in good
condition. All electrical connections should
be subject to quality and functional checks.
Loose connection will, sooner or later,
create sparks and components damage. Dirt
and humidity will create short cuts.
Use blade connectors, ring and spade
terminals and appropriate cable end sleeves.
Ensure insulation of each single connection
and between the different terminals. Loose
flexible wires connected to terminals will
cause arcing and sparks!
Figure 20: Appropriate wire connectors
34
Step 8)
Figure 21: Appropriate cable end sleeves
Compressor terminal
sealing caps must be tight
and the wire connection
screws be fastened.
Wire connections should
be in good condition and
properly isolated to avoid
arcing.
Figure 22: Loose connection causes arcing and
short-cut
Figure 23: Not acceptable capacitor may cause
short-cut and sparks
35
Step 8)
Mains contactors (either
the existing or new one)
must be fitted into a
sealed enclosure.
Figure 24: Replace contactor into isolated box!
The clearance between
fan blade and housing
must be sufficient to avoid
any impact.
Compressor rubber
grommets and sleeves
must be in good condition
to avoid vibration.
The level of vibration
associated with the
system must be within
normal, acceptable limits;
too much vibration implies
that there is a greater
possibility of leakage
therefore compromising
safety.
Refrigerant transfer tubes
most have enough space
in-between to avoid
rubbing on each other, so
that chafing is avoided.
36
Step 8)
Capacitor connections
should be either sealed
with a cap and factory
assembled cable, or the
wires connected via an
isolated spade type
connector.
Potential SOI:
mains contactor
Check capacitor
-> Okay
Check that compressor
terminal is sealed
Check fan motor
and capacitor
Check rubber grommets,
sleeves and tubes
Figure 25: Checking the outdoor unit
Capacitors
acceptable
Terminal and
wiring
acceptable
Mains contactor
replaced
Figure 26: Replacing mains contactor and checking
capacitors
Step 9)
Not applicable
Set-up emergency
ventilation/detection and
alarm system
-> Okay
37
AC system commissioning with HC R290
Step 10)
Integrity test (pressure
test / strength test
Since the refrigerant circuit has been broken
into by replacing the flared tube couplers /
suction and liquid line and the filter-drier, it
is necessary to carry out leak tightness tests
and strength pressure tests.
This is carried out simultaneously by
pressurising the system with oxygen-free dry
nitrogen (OFDN) to the maximum working
pressure (PS) of the system or system
sections (as stated on the data plate) plus
10% (according to EN 378-2).
Pressure Test Value =
1.1 × PS (2.55 × 1,1) = 2.80 MPa (28 bar)
Figure 27: Pressure / strength test with OFDN
38
Step 10)
i)
Nitrogen cylinder is connected with a
common but reliable transfer hose to
the service port of the outdoor unit. For
safety reason, with starting of the test
procedure, the pressure adjusting handle
of the pressure regulator is back-seated
(pressure regulator discharged).
ii) Nitrogen is now transferred to the
system by slowly adjusting and opening
the pressure regulator (pressure
adjusting handle) and carefully applied
at a pressure of 28 bar (2.8 MPa) to the
system.
iii) Check every single joint, connection and
component for bubbles using soapy
water or other such fluids.
iv) If a leak is identified, follow the
appropriate procedures to repair it.
v) If the system is found to be free of
leaks, release the OFDN from the
system slowly and carefully to the
ambient.
Flushing the system with OFDN will require
the same work activities and equipment
provisions but with applying lower pressure
(max. 10 bar).
-> Okay
39
Step 11)
Temporary flammable
zones
Strategically plan the work schedule in order
to have tools and equipment direct available
and to avoid having to change the equipment
and refrigerant hose interconnections during
servicing the AC unit with HC.
When working on systems using flammable
refrigerants, the technician should consider
certain locations as “temporary flammable
zones”. These are normally regions where
at least some emission of refrigerant is
anticipated to occur during the normal
working procedures, such as recovery,
charging, and so on; typically where hoses
may be connected or disconnected.
Place warning signs within
the working area.
Make sure that the gas
detector is operational and
place it on the floor within
the work area. This will
give a clear indication if
HC refrigerant is in the
surrounding environment.
40
In general, the work schedule for refrigerant
handling during service and repair activities
should be arranged in a manner that the
release of refrigerant is not necessary (e.g.
„pumping down“ the system and moving the
refrigerant charge to the high side of the
system). In anticipation of the maximum
quantity of refrigerant that may be released
during such a procedure (such as disconnecting a hose whilst it is full of liquid refrigerant), the minimum distance in all directions
and with respect of the occupied working
area where the service equipment is placed,
should be a minimum of two metres.
Step 11)
Indoor
Unit
Outdoor
Unit
Figure 28: Temporary flammable zones
For any reason and under specific circumstances
where service or repair activities have to be carried
out at the indoor unit (breaking into the refrigerant
caring system), the designated two (2) metres
safety area will apply the same way as indicated
for the outdoor unit!
-> Okay
41
Step 12)
System Evacuation and
charging
The diagram below indicates the arrangement
of equipment and tools and the interconnection with refrigerant hoses for drawing a
vacuum at the system and finally charging
with refrigerant. These are activities in
general where flammable refrigerant can be
present. It is important to respect the temporary flammable zones, as indicated before, for
carrying out intended work activities and
arrangement of the safety area.
The process of evacuation requires the use of
a suitable vacuum pump and electronic
vacuum pressure gauges; the system should
maintain a vacuum of 200 microns (0.5 mbar,
50 Pa), held for at least 15 minutes (without
the pressure changing).
Indoor
Unit
Outdoor
Unit
Figure 29: Equipment and tools arrangement for
vacuuming and charging
42
Step 12)
The process of charging the AC systems with HC
refrigerants is similar to those using halocarbon
(e.g. HCFC R22) refrigerants. Since R290 is a pure
refrigerant the charging can take place in gaseous
or liquid state. For small amounts of refrigerant
(as for this example 0.280 kg) the charging of
this system can be done by taking only vapour from
the refrigerant cylinder and charging to the suction
line of the compressor by measuring the weight of
refrigerant. If charging the refrigerant in liquid
form to the suction side of the system it must be
evaporated before it reaches the system. Interconnect an expansion device (e.g. a short length of
capillary tube) between the hose and the system,
to enable the refrigerants evaporation. The charging
amount should be monitored by the use of an
accurate and sensitive scale. For safety reasons
and to provide accurate charging, the smallest
refrigerant cylinder sizes possible should be used.
-> Okay
43
Step 13)
Apply relevant
documentation and
system markings.
Figure 30:
Warning
sign at the
compressor
Warning sign at the
compressor
-> Okay
Conversion label with
detailed information at
the outdoor unit
Warning signs at the
outdoor unit
Figure 31: Labelling of the outdoor unit
44
Step 14)
Final leak checking
With an HC gas detector
– check every single joint,
connection and component
for the presence of
refrigerant.
Using a bubble test –
check every single
joint, connection and
component is checked
for bubbles using
soapy water or other
such fluids.
Figure 32: Bubble test
-> Okay
End of AC system
conversion
Figure 33: Leak check with electronic leak detector
Note:
For the use with Hydrocarbon refrigerants
(here HC R290) it is important to make sure
that the detector is safe and sensitive for this
refrigerant. Regular used electronic gas
detectors for CFCs, HCFCs or HFCs refrigerants
are in most cases not designed for the use
with HC R290, so check with the equipment
provider and review the product manual if the
gas detector is safe for a specific use.
45
Table 3: PT chart for R290 HC refrigerant
46
47
Table 4: Start-up Record - AC system conversion to HC R290
Start-Up Record – AC system conversion to HC R290 refrigerant Service Company
Service Company
Address
Telephone & Fax
Technician Name
Registration No.
Client / Company
Contact Person / Telephone No.
Installation / Appliance DATA
Manufacturer and type
Refrigeration capacity rating
Date of Installation / year
Initial refrigerant type and charge
Amount of recovered refrigerant
Comments / Repair
Replaced parts and conversion activities
(1)
(2)
(3)
Pressure / strength test – OFDN pressure value
Operating data after conversion – Cooling mode
Refrigerant Type
Refrigerant Name
Refrigerant charge in kg
Suction Pressure
Flammable
Suction Temp
Refrigerant
Air Temp. entering condenser
Air Temp. leaving condenser
Air Temp. entering evaporator
Air Temp. leaving evaporator
Electrical Data
Power Supply
Overall Ampere Reading
Current draw Compressor
Other executions for system commissioning - tick box for completion!
Only use correct and reliable tools / equipment for system commissioning!
All flared (mechanical) connections are removed from occupied space!
There are no sources of ignition (SOI) left at the system (indoor & outoor)
Check system function!
Check the AC system for HC leakage (bubble test and with electronic
leak detector)!
Check that electrical connections are tight and proper insolated!
Check that condensate drain is tight and with down-grade!
Check condition of refrigerant transfer tubes insulation!
Check free run of condenser and evaporator fans!
Check system operation (indoor/outdoor) on abnormal operational noise!
Clean system components including air filter (if indicated)
Check function of remote controller!
Execute briefing of the AC system user!
Company signature and date:
Client signature and date:
48
Table 5: Service label to be place at the outdoor unit after conversion and
service / repair.
Flammable Refrigerant R290 Service
Company
Name of Technician
Address
Telephone & Fax No.
Registration No.
This System
is charged with the natural and
environmental protective
Refrigerant R290
Flammable Refrigerant
Refrigerant Charge in kg
Lubricant Type & Charge
Date:
Signature:
49
This conversion guide is intended to assist with the safe
conversion of air conditioning systems to use flammable
hydrocarbon (HC) refrigerants. Converting an air conditioning
system from a non-flammable to a flammable refrigerant
requires special considerations, which are summarised here.
Deutsche Gesellschaft für
Internationale Zusammenarbeit (GIZ) GmbH
Programme Proklima
Dag-Hammarskjöld - Weg 1 – 5
65760 Eschborn / Germany
Telefon: + 49 61 96 79 - 1022
Telefax: + 49 61 96 79 - 80 1022
E-Mail: [email protected]
Internet: www.giz.de/proklima
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