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Table of Contents
Combustion ........................................................................................................................................................... 3
Procedure for carrying out a service with the aid of a Combustion Analyser. ............................................... 3
Appliance testing BS 7967-3 ................................................................................................................................ 4
Carrying out a room test with a Combustion Analyser. ................................................................................... 5
Pipe work inspection .......................................................................................................................................... 6
Re-establishing gas supplies ................................................................................................................................. 6
Testing for tightness (Using Gas) NEW SYSTEMS ......................................................................................... 7
Air testing .............................................................................................................................................................. 7
Testing for tightness (Using Gas) Existing Systems .......................................................................................... 8
Testing for tightness (Using Gas) Maximum Operating Pressure (MOP) greater than 75 MB ................... 9
Tightness testing Flow Chart ............................................................................................................................. 10
Ventilation ........................................................................................................................................................... 11
Meter Standing and Working Pressure ............................................................................................................ 13
Inlet working pressure ....................................................................................................................................... 13
Burner pressure .................................................................................................................................................. 13
Heat Inputs And Gas Rates. .............................................................................................................................. 14
Gas Rate Tables .................................................................................................................................................. 15
Gas safety devices and Controls ........................................................................................................................ 16
Additional Info for Cooker Controls ................................................................................................................ 20
Unsafe situations ................................................................................................................................................. 22
Flue inspection .................................................................................................................................................... 22
Room sealed flues................................................................................................................................................ 22
FLUE TESTING ................................................................................................................................................. 23
SPILLAGE TESTING ....................................................................................................................................... 24
Spillage Testing for room sealed appliances ..................................................................................................... 25
Positive Fan Pressure ......................................................................................................................................... 25
Appliance list ....................................................................................................................................................... 25
Flue Termination Points..................................................................................................................................... 26
Condensation and pluming. ............................................................................................................................... 27
Typical Gas Component Faults on Central Heating Boilers and Circulators ............................................... 28
Typical Gas Component Faults On ................................................................................................................... 29
Cookers ................................................................................................................................................................ 29
Typical Gas Component Faults On ................................................................................................................... 30
Space Heating (gas fires) .................................................................................................................................... 30
Typical Gas Component Faults On ................................................................................................................... 31
Warm Air Units. ................................................................................................................................................. 31
Typical Gas Component Faults On ................................................................................................................... 32
Volume and purge calculations for large installations .................................................................................... 33
Pipe work sizing ......................................................................................................................................................
Notes: ................................................................................................................................................................... 37
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Combustion See www.gb-gas.co.uk for more details.
Visual inspection
The main reasons for incomplete combustion
1. Lack of oxygen (soft yellow flames)
2. Incorrect burner pressure (over gassed / under gassed)
3. Flame impingement (flame chilling)
A good pre-aerated flame should be bright blue with a strong inner and outer cone,
and above all will have a roar. If there is any yellow in the flame then it is incorrect.
(Do not mistake yellow for orange, as orange flames are usually dust being burnt.)
Procedure for carrying out a service with the aid of a Combustion
Analyser.
1. Carry out the service as per manufacturer’s instructions
 Tightness test, clean and inspect.
2. If the appliance is range rated turn to maximum setting
 Traditional boilers adjust to max burner pressure.
 Combination boiler on hot water mode or chimney sweep mode.
 Condensing boilers check manufacturer’s instructions.
 All other appliances burner(s) on full.**
**Be aware that checking a eye level grill when the hob burners are on will cause
incomplete combustion on the grill.
3. Take flue gas analysis
If acceptable:
Reset to original burner pressure / gas rate and retest if ok
Then conduct:
 Flue and spillage test
 Check safety controls.
 Ventilation.
 Confirm safe operation
If unacceptable:
If possible rectify fault(s) then re test
If not possible follow the unsafe situations guidelines.
 At Risk for flued appliances
 Immediately Dangerous for Flueless appliances.
4. Complete job documentation
If using a flue gas analyser acceptable readings vary depending on the
appliance type. Consult manufacturers’ instructions. If the manufacturer
supplies a Co2 reading only then make sure you are very close to that
reading.
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Appliance testing BS 7967-3
APPLIANCE TYPE
Back boiler unit
Boiler
In combination with
fire
CO/CO2 RATIO
0.008
0.020
Central heating boiler
Hot water circulator
Flued space heater
0.008
0.010
0.020 (check man
instructions)
Flueless space heater
0.001
Water heater flued and Flueless
0.020
Warm air heater
0.008
Flueless cooker
Oven
0.008
Hob
Visual inspection of
flames
Grill (CE marked)
0.010
Grill (No CE mark)
0.020
Range oven flued
0.020
Refrigerator (LPG)
0.007
Tumble drier
Flued
0.010
Flueless
0.001
Gas lights (LPG)
0.020
Maximum Carbon Monoxide in a Flue (CO) = 350ppm
Any ratios above these readings maybe through, misuse, lack of maintenance,
damage or aging.
Make sure the probe is placed correctly:
Open flued: centre of the flue, or 200mm
inside the draught diverter.
Room sealed: From the manufacturers
test point or 200mm inside the flue duct
from outside
Flueless appliances: On the flue outlet
using
the spreader bar tester.
COMBUSTION
C
ANALYSER
Natural gas
The appliance has run for 5 mins.
Monitor the Co reading carefully if this
starts rising quickly then remove the tester
as you may damage the equipment.
Co…. 21
O2… 4.8
Co2...8.9
Most analysers work out ratios automatically. The
°
calculation is: °/°2  =
(°2 ×10,000)
Page | 4
If you don’t get the reading you are
looking for let it run for a further 10 mins
and retest.
A full clean and check or repair of the
appliance is essential and then re-tested.
If it is not possible to achieve these levels
then the appliance should be regarded as
At Risk for flued appliances and
Immediately Dangerous for Flueless
appliances.
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Carrying out a room test with a Combustion Analyser.
General
1. Position an open ended sampling probe approximately 2 m above floor level
in the centre of the room and at least 1 m away from any suspect appliance
installation.
2. Close all external doors, windows and customer adjustable ventilation.
3. Record the level of CO over a 15 min period. If the indoor level of CO starts to
rise during this period, check for CO migration from other sources. Maximum
Level with no appliances on is 30ppm.
4. If there is no rise then proceed to test the appliance.
Operate the appliance at full rate until the CO reading stabilizes or begins to fall,
Room
sealed and whichever occurs first.
open flued
appliances
Cookers
Ensure that all permanent ventilation to the space in which the appliance is situated
is unobstructed.
Place a saucepan on each of the pan-supports above the two largest hotplate
burners and put approximately a litre of water in each and cover with a lid. Use a
saucepan with a flat base and a base diameter of between 160 mm and 220 mm.
Place the grill pan in its highest position under the grill.
Open/operate the customer adjustable ventilation in accordance with the cooker
manufacturer’s instructions, e.g. window or extractor fan.
Light the grill, oven and the two hotplate burners at their maximum setting. Turn the
oven down to gas mark 5 (or mid-range if not calibrated in gas mark numbers).
Record the CO levels at 1 min intervals.
Turn the hotplate burners down to simmer when the water boils. Turn the grill off
after 30 min.
If during the test the CO reading:
begins to fall without exceeding 30 ppm, stop the test; the installation and cooker are
satisfactory;
does not exceed 30 ppm for longer than 20 min and begins to fall and does not
exceed 90 ppm at any time, stop the test; the installation and cooker are satisfactory;
Exceeds 90 ppm at any time, stop the test, ventilate the room, identify the cause,
rectify and repeat the test.
Flueless
water
heaters
Flueless
space
heaters
Ensure that all permanent ventilation to the space in which the appliance is situated
is unobstructed.
Close all customer adjustable ventilation to the space in which the appliance is
situated.
Light the appliance and operate it at maximum gas rate for 5 min recording the CO
levels at 1 min intervals.
Ensure that all permanent ventilation to the space in which the appliance is situated
is unobstructed.
Close all customer adjustable ventilation to the space in which the appliance is
situated.
Light the appliance and operate it at maximum gas rate for 30 min recording the CO
levels at 1 min intervals.
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Pipe work inspection See www.gb-gas.co.uk for more details.
Common faults found on the meter installation:
Adopt a step by step procedure to find any faults at the meter installation.
An experienced checklist will find any errors or omissions compared to the British Standards.
Key Word
1
2
3
4
5
6
7
8
Yes / No
Corrosion
Any signs of corrosion?
Secure
Is the meter secure?
Handle
Is the valve handle secure and drops to the off position?
On / Off
Is the on / off label present?
Pipework
Is the inlet anaconda pipe work correct?
Regulator
Is the regulator on the correct way and the cover cap sealed?
Meter
Is the meter the correct way around?
Label
Is the meter label fitted does it display all the details
If any faults are present then the Gas Supply should be contacted for primary meters
Common faults found on pipework installation:
Key Word
Yes / No
Bonding
10mm² Earth bonding within 600mm of the meter or inside house
Sleeves
Is the pipe sleeve correct and sealed inside?
Clipped
Are the Pipes clipped at appropriate distances?
Pipes
Are all the pipes appropriate for gas?
Fittings
Are all the fittings appropriate for gas?
Corrosion
Any signs of corrosion or protected from corrosion?
Electrics
Are the pipes to close to electrical services
25mm from cables and conduits 150mm from outlets
Ducts
8
Are pipes in ducts ventilated where required
Joists
9
Are notches in joists correct depth (1/8) and within distance from
supporting wall (1/4) span
Faults
10 Is there any other unsatisfactory faults
If any faults are present then they must be repaired or dealt with in the unsafe situations procedure
1
2
3
4
5
6
7
Re-establishing gas supplies
This checklist should be conducted every time the gas has been turned off. Even if only conducting a
tightness test.
1. A visual check on the pipework installation
2.
3.
4.
5.
A visual check of the appliances should be made
Visual check & Calculate the ventilation requirements for the installation
Test for Tightness
Purge the meter from the furthest practical point
Purge volume = 5x the meter badge capacity for installations with pipe up to 28mm
e.g. ( imperial meter(ft³) = 5x 0.071ft³ = 0.355ft³) (metric meter(M³) = 5x 0.002m³ = 0.010m³)
If there is pipework greater than 28mm or a meter bigger than a 6m capacity a calculation must be used
U16 meter
Purge volume = pipework length x volume of 1m length x 1.1 (for fittings) plus meter volume x 1.5.
E.g. 3 m of 35mm pipe plus a U16 meter... 3 x 0.00084 x 1.1 + 0.025 x1.5 =0.0416 m³. =0.042 m³.
See page 32 or IGEUP1B FOR MORE DETAIL or visit gb-gas.co.uk
6. Purge the remaining sections of the installation (light and detect method)
7. Re-light each appliance in turn checking that all user controls are working
satisfactorily
8. Check all open flued appliances for spillage
9. Inform customer on appliance use and gas safety
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Testing for tightness (Using Gas) NEW SYSTEMS
See www.gb-gas.co.uk for more details.
After visually inspecting the installation
1. Turn the gas off
2. Make sure all appliances are disconnected
3. Turn all valves on pipework on.
Connect a zeroed manometer to the meter test point and start the test procedure
Test name
Reason
Let-by test
To check if MCV is
passing, if greater than
(max 0.25mb or 0.2mb
with a digital) report to
supplier. To confirm let-by
spray LDF in valve
to allow for temp.
differences
Stabilisation
Tightness
test
(No pressure drop or smell
allowed)
Test pressure
Test time
7-10mb
1 min
20-21mb
1 min
 20-21mb
2 min
4. Make sure all appliances are re-connected
5. Turn all valves on including lifting the cooker lid.
Connect a zeroed manometer to the meter test point and start the test procedure
Test name
Reason
Stabilisation
To allow for temp.
differences
Test pressure
20-21mb
Test time
1 min
Tightness
(record any drops here)
2 min
 20-21mb
test
Gas test for pipework and appliances in new installations
NO DISCERNABLE DROP ALLOWED –(max 0.25mb or 0.2mb with a digital)

The test pressure must never be greater than 23mb as the governor may lock
up, if this happens during the stabilisation, drop the pressure back down.
Spray all the inlet pipework and test points to check for leaks.
Air testing
Connect a zeroed manometer to the TEST TEE and start the test procedure.
Test name
Reason
Test pressure
Test time
Stabilisation
to allow for temp.
20-21mb
1 min
differences
Soundness
(record any drops here)
20-21mb
2 min
test
Air test would be used for pipework in new installations
NO DISCERNABLE DROP ALLOWED -(max 0.25mb or 0.2mb with a digital)
******** Test all test points with leak detector fluid*********
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Testing for tightness (Using Gas) Existing Systems
After visually inspecting the installation
1. Turn the gas off
2. Make sure all appliances are connected
3. Turn all valves on pipework on.
Connect a zeroed manometer to the meter test point and start the test procedure
Test name
Reason
Let-by test
To check if MCV is
passing, if greater than
(max 0.25mb or 0.2mb
with a digital) report to
supplier. To confirm let-by
spray LDF in valve
To allow for temp.
differences
Stabilisation
Soundness
test
(see information below)
Test pressure
Test time
7-10mb
1 min
20-21mb
1 min
 20-21mb
2 min
 If there is no discernable pressure drop in the system and no
smell of gas then the system has passed.
 If there is a drop in the system then all the appliances must be
isolated and the pipework tested on its own (no discernable drop
is allowed in the pipework)
 If the drop is at an appliance and within the limits set (below) and
no gas can be smelled, then the system may be passed.
 The test pressure must never be greater than 23mb as the
governor may lock up, if so you will have to spray all the inlet
pipework to check for leaks.
Maximum drop allowed
U6 meter
4mb over 2min* or
2.5 mb if there is
pipe work greater
than 28mm
E6 meter
or
No meter
8mb over 2min*
4 mb if there is pipe
work greater than
28mm
U16 meter 1mb over 2 min* even if the pipe is greater than 28 mm
* in any situation if the recorded drop is in the pipework it is an immediate fail
* if there is a sell of gas the installation is an immediate fail
******** Test all test points with leak detector fluid*********
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Testing for tightness (Using Gas) Maximum Operating Pressure (MOP) greater than 75 MB
After visually inspecting the installation
1. Turn the gas off
2. Make sure all appliances are connected and no pilot lights
3. Turn all valves on pipework on.
Connect a zeroed manometer to the meter test point and start the test procedure
Test name
How
Reason
Test
pressure
Let-by test
for Meter
Control
Valve (A)
Take the system up to
standing pressure.
Close meter control
valve.
Release pressure e.g. (by
opening a cooker)
Hold open regulator valve
and observe.
Release the regulator
valve pressure should
increase slightly.
Open meter control valve
and observe.
To check if MCV
is passing, if
greater than
(max 0.25mb)
report to supplier.
To confirm let-by
spray LDF in
valve
to check if
regulator is
passing on lock
out, if greater
than (max
0.25mb) report to
supplier
To allow for temp.
differences
Approx. 1 min
Let-by test
for
Regulator
lock out (B)
Stabilisation
Raise pressure to 19 mb
close meter control valve
Soundness
test
Observe
(No discernable
pressure drop or
smell allowed) 
Test
time
710mb
Approx. 1 min
710mb
19mb
1 min
19mb
2 min
 No discernable drop is any drop greater than 0.25mb
 The test pressure must never be greater than 19mb as the governor
may lock up,
 Because the inlet pipework is subjected to pressures up to 2 bar you
must spray all the inlet pipework to check for leaks.
Maximum drop allowed
U6 meter
4mb over 2min* or
2.5 mb if there is
pipe work greater
than 28mm
E6 meter
or
No meter
8mb over 2min*
4 mb if there is pipe
work greater than
28mm
U16 meter 1mb over 2 min* even if the pipe is greater than 28 mm
* in any situation if the recorded drop is in the pipework it is an immediate fail
* if there is a sell of gas the installation is an immediate fail
******** Test all test points with leak detector fluid*********
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Tightness testing Flow Chart
Let by test @
7-10mb for 1 min
Raise greater than
0.25mb?
Fall greater than
0.25mb ?
No discernable raise
or drop?
MCV may have let
by or contact the
E.S.P. This must be
repaired and
complete the let by
test again.
Secondary meters
this could be
confirmed (with LDF
in the valve barrel)
There may be a leak
in the system. This
must be repaired and
complete the let by
test again
Stabilisation @
20mb to 21mb
for 1 min
Fall greater than
0.25mb?
No discernible raise
or drop?
There may be a leak
in the system. This
must be repaired and
complete the let by
test again
All times stated are minimums,
these can be extended.
A no discernible drop of 0.25mb
is for a water gauge, other types
of gauge will differ.
Allowable drops in the two
minute test
NO METER
8MB
E6 METER
8MB
U6 – G4 – R5 4MB
OR
IF PIPE WORK GREATER
THAN 28MM IS FITTED
E6 METER
4MB
U6 – G4 – R5 2.5MB
U16 METER 1MB
Page | 10
Tightness @
20mb to 21mb
for 2 min
Fall greater than
0.25mb?
No discernible raise
or drop?
There may be a leak
in the system.
System passes
with no smell
of gas
ON NEW SYTEMS This
must be repaired and
complete the let by test
again
EXISTING SYSTEMS
may pass if the drop is less
than the allowed limits
and no smell of gas
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Ventilation BS5440 Part 2
“When checking ventilation requirements always observe manufacturers instructions”
Calculate MAX NET heat input
= H.I.
Take MAX GROSS heat input from the
appliance DATA BADGE and  by 1.1
Room sealed
Open Flue
Flueless
IN A ROOM
No vent required
1 Vent to outside
Max H.I. x 5cm2 top
Max H.I. x 5cm2 bottom
Max H.I. x 5cm2 top
Max H.I. x 10cm2 bottom
Max H.I. x 10cm2 top
Max H.I. x 10cm2 bottom
Max H.I. x 10cm2 top
Max H.I. x 20cm2 bottom
Vent to outside
Max H.I. – 7kw x 5cm2
Not preferred for new
installations
Ventilation via the roof
space before the 1985
building regs is classed as
direct to outside. After
1985 this should be
ducted or ventilated as via
a room above
Max heat input – 7kw x
5cm2 =
Vent depends on
appliance type and room
volume. Look up the
table page 12
IN A
COMPARTMENT
VENTED DIRECT TO
OUTSIDE
IN A
COMPARTMENT
VENTED THROUGH
THE ROOM
IN A
COMPARTMENT
VENTED VIA A
ROOF SPACE
There are many
allowable
configurations of top
and bottom
ventilation. Consult
the Manufacturer’s
instructions
OPEN FLUED
VENTED THROUGH
TWO ROOMS TO
OUSIDE
Both vents are the same
size.
Max H.I. – 7kw x 5cm2
OPEN FLUED
VENTED THROUGH
MORE THAN TWO
ROOMS AND OR A
COMPARTMENT
Max H.I. x 10cm2 top . Max
H.I. x 20cm2 bottom
Vent to outside=Max H.I. –
7kw x 5cm2
Intermediate vent 50% bigger
than outside vent
OPEN FLUED additional
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TWO Open flued GAS FIRES in the  additional ventilation may not be
same room (less than 14kW)
required
TWO Open flued GAS FIRES in the Add heat inputs together and calculate as
same room (greater than 14kW)
for one open flued appliance in a room
 IF flue or spillage test fails additional ventilation is required
Two or more DFE fires in a room
FLUELESS APPLIANCES
COOKER
WATER HEATER
TUMBLE DRIER
SPACE HEATERS
OPENABLE
WINDOW OR
SIMILAR
YES
YES
YES
YES
100cm2 for first then 135cm2 for each additional
(extra 35cm2 is adventitious ventilation ie 7kw)
= 235cm2 for two DFE fires.
<5
ROOM SIZE (M³)
5-10
10-15 15-20
>20
100 CM²
50 CM² *
0 CM²
0 CM²
0 CM²
NOT
100 CM²
50 CM²
50 CM²
0 CM²
<3.7m³/kW =100cm²
>3.7m³/kW =0cm²
Consult Manufacturer’s Instructions and/or British Standards
* IF THE ROOM CONTAINS A DOOR TO OUTSIDE THEN A VENT IS NOT REQUIRED
MULTI- APPLIANCE SITUATIONS
All Open flued Space Heating……….
or
All flueless Space Heating……………
or
Biggest of any other appliance
Find the largest requirement from the
three rules below
ADD heat inputs together and calculate
Add all vents sizes together
TAKE largest ventilation requirement
Calculate the free air area (measure the smallest parts
of the holes) the hole MUST be from 5 to 10 mm and
not closeable.
if answer is in MM²  100 to get CM²
Measuring
ventilators
Width
Length
The Radius is
half the circle
For Square / Rectangular Holes
Formula = Length x Width x Number of holes.
Example: 5cm x 0.8cm x 30 holes = 120 cm2
For Round Holes
Formula = 3.14 x Radius x Radius x No# of holes.
Example: 3.14x0.5cmx0.5cmx 30holes = 23.55 cm2
Trapezium
Formula = Length x Width x Number of holes.
Example: 4cm x 0.8cm x 30 holes = 96 cm2
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Pressure testing
STANDING PRESSURE at the meter (APPROX. 25mb)
Test method (see below)
WORKING PRESSURE (must be 21± 2 mb) AT THE
METER
Test method (see below)
Multifunction control
APPLIANCE INLET
WORKING PRESSURE
(max 1mb drop form working
pressure at the meter)
APPLIANCE BURNER
PRESSURE (check
against appliance data
badge)
Meter Standing and Working Pressure
1. Connect a zeroed manometer to the meter test nipple.**
2. Turn on gas slowly and record STANDING PRESSURE (APPROX. 25mb)
3. Then turn on ONE appliance: 1.Cooker 3 hotplates.
2.Fire on full rate.
3.Boiler on full rate.*
4.Other appliance full rate.
*a range rated boiler may cause a problem, if using a combi. Use hot water mode
4. Record reading on the WORKING PRESSURE (must be from 19mb to 23mb) if
to high or to low contact gas supplier for primary meter, if it is a secondary meter
adjust (screw down clockwise to increase pressure.)
**To read the manometer correctly add both legs together and divide by 2**
If the meter is running at full rate (6m³/hr), with an inlet pressure of 19mb at the
governor. The drop or (absorption) through the meter will be as much as 4mb.
Inlet working pressure
This test is prove the pipework is suitable in size and length with no blockages.
1. Connect a zeroed manometer to the boiler inlet test point.
2. Turn on the appliance and record the reading( only 1mb drop allowed through
the pipeline) see page 33 for more details
e.g. working pressure at the meter : 21mb
inlet working pressure :
20mb
installation acceptable.
**To read the manometer correctly add both legs together and divide by 2**
Burner pressure
This test is to prove that the appliance is burning within the limitations set by the
manufacturer.
1. Connect a zeroed manometer to the boiler BURNER PRESSURE test point.
2. Turn on the appliance and record the reading (compare the reading against the
appliance data badge. The reading must be within the range)
**To read the manometer correctly add both legs together and divide by 2**
******** Test all testpoints with leak detector fluid*********
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Heat Inputs And Gas Rates.
See www.gb-gas.co.uk for more details.
The purpose of these tests is to prove how much gas is being burnt by the appliance
METRIC METER (M³): E.G. E6, G4, R5
1. Make sure only the appliance to be tested is on (turn up full)
2. Go to the gas meter and record the reading and at the same time start the stop
watch.
3. Two minutes later (on the stop watch) record the second reading.
4. Subtract the first reading from the second reading and apply into the calculation.
EXAMPLE
Reading after two minutes
First reading on meter
Amount of gas used
E6
1
0
0
7

1
3
3
M³
- 1
0
0
7

0
7
2
M³
= 0
0
0
0

0
6
1
M³
GAS RATE = TWO MINUTES OF GAS X 30
=_______________M³/HR
E6 (gross) HEAT INPUT
= TWO MINUTES OF GAS X 317
=_______________Kw
E6 (net) HEAT INPUT = TWO MINUTES OF GAS X 288
=_______________Kw
Compare the reading against the appliance data badge. The reading must be within
the range.
IMPERIAL METER (ft³): E.G. U6, U16
1. Make sure only the appliance to be tested is on (turn up full)
2. Got to the gas meter and time one complete revolution of the red dial on the
meter.
3. Convert the time into seconds and apply into the calculation.
U6
GAS RATE
= 100.8  TIME IN SEC FOR 1FT³ OF GAS
=_______________M³/HR
U6 (gross) HEAT INPUT= 1064  TIME IN SEC FOR 1FT³ OF GAS
=_______________kW
U6 (net) HEAT INPUT = 967  TIME IN SEC FOR 1FT³ OF GAS
=_______________kW
4. Compare the reading against the appliance data badge. The reading must be
within the range.
CV of gas in these calculations is 38kJ allowable range is + 5% - 10%
a free heat input app is available for all major SMART Phones.
Page | 14
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Gas Rate Tables
Page | 15
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Gas safety devices and Controls
See www.gb-gas.co.uk for more details.
Flame supervision devices or
F.S.D s
1
Thermoelectric
Recognise
FSD
Found
Test
Purpose : To avoid unlit gas entering the
appliance
because it has a push button
and thermocouple
in every type of gas appliance
1. Light pilot and establish.
2. Turn gas off time until click
2
Recognise
Loop of metal
Found
Only found on hot water
circulators
1. Light pilot and establish.
2. Turn pilot off time until
burner turns off
Bi-metallic strip
FSD
Test
3
Liquid
Expansion FSD
Recognise
Found
Test
4
Flame
Recognise
rectification FSD
(electronic
Found
ignition)
Test
Small probe directly on oven
burner, burner lights on low
flame
Only found in cookers now
1. Light burner (should light on
low flame) after approx.
30sec rising to high flame.
2. Turn gas tap off, wait for 90
sec and re-light (should light
on low flame)
Ignition starts automatically to
light the pilot or main burner
On all appliances
1. turn appliance on make sure
flame lights and establishes
2. Keep the demand on the
appliance and turn the gas
off. The appliance should go
into lockout or keep sparking
FSD shutdown times
* BOILERS
* W / AIR HEATERS
* COOKERS
* WATER HEATERS
* D.F.E. GAS FIRES
* OTHER GAS FIRES
*
60 SEC
60 SEC
90 SEC oven
60 SEC other
90 SEC
120 SEC
180 SEC
*Manufacturer’s instructions may differ from the times stated above. *
Page | 16
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Purpose: to control heat
Thermostats
4
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Mechanical
thermostat
(Vapor expansion)
Recognise
Dial with numbers indicated
Found
Test
Mechanical
thermostat
(rod type)
Recognise
Mostly on cooker ovens
1. Turn oven on and heat up for 15
min.
2. Turn control to lowest setting
flame should drop to by-pass
rate
Dial with numbers indicated
Found
Test
Old cookers and water heaters.
Heat up appliance gas should turn
down / or off (depending on
appliance)
5
Electric thermostat Recognise
(Vapor expansion) Found
Test
Dial with numbers indicated
Boilers etc
Heat up appliance, thermostat
should turn the solenoid off or
modulate the burner pressure down
6
Electronic
thermostat
Or Thermistor
Recognise
Electronic PCB Appliances
Found
Combi, Water Heaters, Condensing
Boilers etc.
Heat up appliance, the thermistor
will modulate the gas pressure to
the burner, or the fan Approx. 11 -13
kΏ at room temperature.
Turn the tap down in a combi to
see modulating burner pressure or
hear modulating fan slow down
operates modulating
solenoid valve (older
combi) or modulating
fan (new condensing
boiler)
Test
7
Solenoid
Purpose
Found
Test
An electrically operated gas valve
Boilers etc
1. Turn electricity on valve opens
2. Turn electricity off valve closes
8
Modulating
Solenoid
Purpose
An electrically operated actuator
that adjusts a regulator
Older Combi Boilers
1. Open Tap (Full burner
pressure)
2. Close tap to trickle (burner
pressure drops)
Found
Test
9
Old Multi-function
control
Purpose
Found
Test
Page | 17
A collection of controls in one unit
FSD, Regulator, Solenoid
Old Boilers etc.
If the FSD, Regulator and solenoid
work then the multi-function control
is working.
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Old Combi Multifunction control
Purpose
Found
Test
9
Condensing Multifunction control
Purpose
Found
Test
10
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A collection of controls in one unit
Modulating Solenoid + Zero
Regulator + Additional Solenoids ?
Old Combi Boilers etc.
1. If the Regulator and solenoid
modulate then the multifunction control is working.
A collection of controls in one unit
Zero Regulator, Solenoids, Course
adjustment screw
Old Combi Boilers etc.
1. If the appliance operates and
check the flue gas analysis is
correct.
To turn off the burners, when the
lid drops
Cookers, (hotplates)
1. Turn on gas tap to hotplate.
2. Lower lid or close grill door and
gas should turn off
Lid or Grill Door
safety device
Mechanical safety
cut off
Purpose
11
Gas tap
Purpose
Found
Test
To control the flow off gas safely
Cooker, fires ,etc
1. tap locks in the off position
2. tap functions correctly
12
Atmospheric
Sensing
Device
(ASD) (VSD)
Purpose
To close down the open flued
appliance automatically, if the
appliance and flue operate
incorrectly
Found
All open flued appliances after
1998
1. Light pilot.
2. Close air inlet hole and observe
flame (turn yellow)
Found
Test
Test
13
Atmospheric
Purpose
Sensing
Device / over heat
Thermocouple
interrupter
Found
Test
Page | 18
To close down the open flued
appliance automatically, if the
appliance and flue operate
incorrectly
On water heaters, Flued water
heaters this is usually a overheat
safety device. Flueless used as an
ASD
Visual inspection to check wiring to thermocouple
(no links) and check FSD
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Regulator
Purpose
Found
Test
15
Zero governor on a Purpose
atmospheric
burner
Found
Test
16
Zero governor on a Purpose
Pre Mix burner
Found
Test
17
Medium to low
pressure
Regulator
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Adjuster screw to alter burner
pressure
Boilers etc
1. Attach manometer to test point
2. Adjust screw to alter pressure
To compensate for the negative
pressure caused by the fan, on the
gas valve (this could pull more gas
into the burner than intended)
Fan flued room sealed appliances
with atmospheric burners
1. Attach manometer to burner pressure test point
2. Turn appliance on when the fan comes on the
manometer reads negative pressure, quickly
going to positive pressure when the burner
comes on.
To compensate for the
negative pressure caused
by the fan, on the gas valve
(this will give a zero value or
non-usable burner pressure)
Fan flued room sealed
Condensing appliances
with Pre Mix burners
These units must be checked for the correct Air
Gas Ratio and Co/Co2 Ratio by completing a
flue gas analysis
Compare the results with the manufacturers
information
Purpose
To lower incoming gas
pressure from 2 bar to 21mb
Found
Above the meter control
valve, fitted with a reset
handle
1. make sure working pressure is 21mb
make sure the regulator lockout does not let-by
Test
See MOP Tightness testing sheet for a full test
Page | 19
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Additional Info for the Sequence of events for an electronic ignition fan flued boiler
1
Demand on the system turns pump then fan on.
2
Fan turns on fan pressure switch
(pump turns on pump pressure switch)
3
Pressure switch turns on ignition system.
Proving AC to AC through electrodes
4
Ignition system turns on power to the solenoid via the control stat and high
limit stat.
5
Ignition spark ignites the gas
6
Ignition system proves the flame by rectification of the current through the
ionized layer of the flame AC to DC
7
Ignition system monitors flame by DC current
To test the flame rectification system
1 Put a demand on the system and make sure it fires up and stays lit
2
Turn the gas off system should start sparking again then go into lockout or
keep sparking
Additional Info for the Sequence of events Condensing Pre Mix Burner
1 Demand on the system turns pump then fan on.
The Fan runs for 30 seconds to pump any unburnt gas out the flue
2
The ignition system sparks.
Proving AC to AC through electrodes
3
Ignition system turns on power to the solenoid via the control stat and high
limit stat.
4
Ignition spark ignites the gas
5
Ignition system proves the flame by rectification of the current through the
ionized layer of the flame AC to DC
6
Ignition system monitors flame by DC current
To test the flame rectification system
1
Put a demand on the system and make sure it fires up and stays lit
2
Turn the gas off system should start sparking again then go into lockout or
keep sparking
Page | 20
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Additional Info for Cooker Controls
See www.gb-gas.co.uk for more details.
FSD
Vapour pressure
Test procedure






Light the oven burner, it should light on the low flame
After approx. 30 seconds it should rise to the high flame
Turn oven gas tap off
After 90 seconds re-light the oven burner, it should light on low flame
If it lights on the high flame then the FSD is faulty
If it does not rise to the high flame then the FSD is faulty
OR
Thermoelectric
Test procedure







Push the control handle in and turn to a setting.
Light the burner hold in the control handle for 30
seconds
Release the control handle the flame should stay
on the burner.
If the flame goes out the thermocouple or
thermoelectric valve is faulty
Turn the gas off, at the meter or appliance
isolation valve, after the flame goes out at the
burner time until a click is heard or the time limit is
reached.
Turn the gas back on without pushing in the control knob in ,the gas should
not come back through the burner
If the gas comes back on thermoelectric valve is faulty
Oven thermostat
Test Procedure







Light the oven burner and turn to high setting
Shut the door and leave for 15 min
Open the door to see the flames and turn to the lowest
possible setting
The flame should drop to the bypass rate
If flame goes out (faulty bypass)
If flame does not drop (faulty thermostat)
Page | 21
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Unsafe situations
To find out if a situation is NCS AR or ID consult the unsafe situations document
Category
N.C.S.
NOT TO
CURRENT
STANDARDS
A.R.
AT RISK
I.D.
IMEDIATELY
DANGEROUSE
Action taken
Label used
Notice used
Inform responsible person, and repair
fault if possible. Fill in (notice) and
give copy to responsible person
None
Inform responsible person, and repair
fault if possible. If not turn appliance
off attach (label) and fill in (notice) and
give copy to responsible person.
Inform responsible person, and repair
fault if possible. If not DISCONNECT
appliance and attach (label) and fill in
(notice) and give copy to responsible
person.
Warning label do
not use
Fill in the NCS
section of
warning notice
form
Fill in the A.R.
section of
warning notice
form
Fill in the I.D.
section of
warning notice
form
Warning label do
not use
Copies of the unsafe situations procedure are available to download from the HSE website…………
see website for the latest link
Flue inspection
When visually inspecting a flue, start at one end and work methodically to the other
end making a note of all the problem areas. Common faults to look for are:
Open flues
Key Word
1
2
3
4
5
6
7
8
9
10
Is the catchment area the right size, sealed, with correct
configuration?
Does the catchment area have a data badge / plate?
Is the flue the correct diameter, undamaged and running in the
correct configuration?
Is the flue appropriate for the appliance?
Is the flue clipped adequately?
Are the bends no closer than 600mm from the draught diverter
and less than the maximum angle (45º) or (30º) for precast?
Is the flue pipe to close to combustible material?
Is the terminal the right size, type, and correctly configured?
Are all components sealed appropriately?
Are there any signs of spillage?
Yes / No
Catchment
area
Data plate
Size
Damage
Material
Clipped
Bends
Access
Combustible
Terminal
Sealed
Spillage
Room sealed flues
Key Word
1
2
3
4
5
6
7
8
9
Is the flue length and route ok?
Is the flue joins sealed appropriately?
Have the correct materials been used?
Is the flue supported adequately?
Is the terminal in the correct position?
Does the terminal require a terminal guard (below 2 m)
Does the flue duct have access points 300mm x 300mm hatch
placed within 1.5m of joints in the flue
Is the flue or terminal damaged?
Are there any signs of spillage or fumes entering the building?
Page | 22
Yes / No
Length
Sealed
Materials
Clipped
Terminal
Guard
Ducting
Access
Damage
Spillage
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FLUE TESTING
See www.gb-gas.co.uk for more details.
The purpose of a flue test is to prove a few points about the flue:
1. Flue draws all the products of combustion up the flue.
2. The flue does not leak from any joints or connections.
3. The flue terminates in the correct position.
4. The flue does not leak through any other flue system.
Before carrying out the test a few points MUST be covered.
1. Explain to the customer what you are about to do (in case they panic)
2. Close doors and windows (put the flue under its worst conditions)
3. When testing a flue with a fan in the area (it is not necessary to turn the fan on as
the problems that may occur with back pressure are checked when conducting a
spillage test)
4. Pre testing the pull with a smoke match before putting a smoke pellet into the
flue, can avoid large quantities of smoke in the room and lowers the inhalation of
Co from the smoke.
Flue pellets must produce at least 5m³ of smoke in 30
seconds. (BS5440prt1) Engineers using Smoke Pellets that
produce a lot more than this must be aware of unfair testing
procedures.
i.e. a pellet producing 7 m³ in 45 seconds
45
= = 6.43   ³
7
30
Compared to the standard
= 6   ³
5
These
pellets
would
be
deemed
as acceptable.
IMPORTANT. While completing
the test;
1. *All (the greatest majority of) smoke must be drawn into the flue.
2. The smoke must terminate at the correct point.
3. The flue must not leak into any other flue, room or dwelling
If heating the flue with a blow torch, it may require as much as 30 min to heat
properly. If using an appliance this should be in half this time
Page | 23
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SPILLAGE TESTING
See www.gb-gas.co.uk for more details.
The purpose of a spillage test is to prove a few points about the appliance:
1. The appliance draws all the products of combustion into the flue.
2. The appliance and flue design are working correctly.
3. The appliance has no fumes entering the room
4. The appliance is safe to use
Before carrying out the test a few points MUST be covered.
1. Explain to the customer what you are about to do (in case they panic)
2. Close doors and windows (put the flue under its worst conditions)
3. leave the extractor fans off in the house and complete first test
4. If step 3 passes. Turn extractor fans on in any other room in the house and
leave the door between the rooms open and the appliance. Complete second test
5. If the appliance fails when the fans are on but passes when they are off additional
ventilation is required.
IMPORTANT
while completing the test;
*All (the majority of) smoke should be drawn into the appliance
The appliance must be left on at maximum setting.
Page | 24
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Spillage Testing for room sealed appliances
See www.gb-gas.co.uk for more details.
•
•
•
•
•
This to make sure the appliance is sealed form the room.
Remove the outer case if it is not part of the seal.
Visually inspect for any corrosion, distortion and problems with seals
While the appliance is turned on
Move a lighter or match around
1. All the case seals,
2. Viewing windows,
3. All Pipes and wires entering the
pressurised case
4. Around the flue seals
•
If the lighter flame is distorted or
blows out then this is a fail.
Positive Fan Pressure
Appliance list
Manufacturer and Model
Alde International (UK) Ltd
Alde 2927 Slimline
Brassware Sales Ltd
Ferrolli 76FF
Ferrolli 77FF
Crosslee (JLB) (Pyrocraft)
AWB 23.09 WT Combi
Crosslee (Trisave Boilers Ltd)
Trisave Turbo T45
Trisave Turbo T60
Trisave Turbo 30
Trisave Turbo 22
Glow-worm Ltd
Economy 30F
Economy 40F
Economy 50F
Glow-worm Fuelsaver 35F
Glow-worm Fuelsaver 45F
Glow-worm Fuelsaver 55F
Glow-worm Fuelsaver 65F
Glow-worm Fuelsaver 80F
Glow-worm Fuelsaver 100F
Glynwed Domestic & Heating
AGA A50
AGA A50 A
AGA A50 NG
AGA A50 SS
AGA A50 ANG
AGA A60
AGA A50 NG
AGA A75 NG
Page | 25
Manufacturer and Model
Manufacturer and Model
Glynwed Domestic & Heating (cont.)
Highlight P50
Highlight P50A SC
Highlight P50S
Highlight P50SS
Highlight P50S/A
Highlight P50S/A GLC
Highlight P50S/A SC
Highlight P50/A
Highlight P70
Highlight P70S
Highlight P70SS
Myson (Thorn) Olympic 38/50F
Myson (Thorn) Apollo Fanfare 15/30
Myson (Thorn) Apollo Fanfare 30/50
Supaheat 50/15 with “A” control
Supaheat GC 50/15
Netaheat MkI 10/16
Netaheat MkI 16/22 BF
Netaheat MkII 10/16 BF
Netaheat MkII 16/22 BF
Netaheat MkIIF 10-16 BF
Netaheat MkIIF 16-22 BF
Netaheat Electronic 6/10
Netaheat Electronic 10/16
Netaheat Electronic 16/22
Netaheat Electronic 10/16e
Netaheat Electronic 16/22e
Halstead Heating & Engineering Ltd
Halstead 45F
Halstead 55F
Halstead 65F
Wickes 45F
Wickes 65F
Barlo Balmoral 45F
Barlo Balmoral 55F
Barlo Balmoral 65F
Harvey Habridge Ltd
Impala MkII
Impala MkII Ridgeseal
Impala
Impala Super 2 (VF)
Potterton Myson Ltd
Netaheat Profile 30e
Netaheat Profile 40e
Netaheat Profile 50e
Netaheat Profile 60e
Netaheat Profile 80e
Netaheat Profile 100e
Myson (Thorn) Olympic 20/35F
Stelrad Group Ltd
Ideal Elan 2 40F
Ideal Elan 2 50F
Ideal Elan 2 60F
Ideal Elan 2 80F
Ideal Excel 30F
Ideal Excel 40F
Ideal Excel 50F
Ideal Excel 60F
Ideal Sprint 80F
Ideal W2000 30F
Ideal W2000 40F
Ideal W2000 50F
Ideal W2000 60F
Worcester Bosch
Heatslave 9.24 RSF
Worcester 9.24 Electronic RSF
Worcester 9.24 Electronic RSF ‘S’
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Flue Termination Points
Distances (in mm)
D Below a gutter, or
sanitary pipe work
E Below the eaves
F Below a balcony or
carport roof
G Above ground, roof
or balcony level
H From vertical
drain/soil pipe work
J From an internal or
external corner
K From a surface or
boundary facing the
terminal
L Vertically from
terminal on same wall
M Horizontally from
terminal on same wall
N From a terminal
facing the terminal
P From an opening in a
carport (e.g. door,
window) into the
building
R From a vertical
structure on the roof
[Note $]
S Above an intersection
with the roof
Natural
Fan
draught draught
300 [#] 75 [@]
300 [#]
200
600
200
300
300
75 [@]
75 [@]
600
300
600
600 [+]
1500
1500
300
300
600
1200
1200
1200
n/app
n/app
n/app
n/app
Notes:
@. a terminal serving a natural draught and fanned draught
appliance more than 5kW heat input should be at least 300mm
and 150mm respectively from combustible material.
#. Where a natural draught flue terminates not more than 1m
below a plastic projection or not more than 500mm below a
projection with a painted surface, then a heat shield at least 1m
long should be fitted.
+. The distance from a fanned draught appliance terminal
installed at right angles to a boundary may be reduced to 300mm
$. Vertical structure includes a chimney-stack, dormer window,
tank room, lift motor room or parapet.
Minimum distance to terminal in millimetres
Balanced flue, room-sealed
appliance
Natural draught Fanned draught
A Directly below an
opening, air brick,
opening window, etc
B Above an opening,
air brick, opening
window, etc
C Horizontally to an
opening, air brick,
opening window, etc
Page | 26
(0-7 kW)
(>7-14 kW)
300
600
300
300
(>14-32 kW)
1500
300
(>32-70 kW)
(0-32 kW)
(>32-70 kW)
2000
300
600
300
300
300
(0-7 kW)
(>7-14 kW)
(>14-70 kW)
300
400
600
300
300
300
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Condensation and pluming.
•
•
Facing properties and points of possible extensions in the future
must be a consideration.
A distance of 2m is recommended where pluming may be a
nuisance. To openings or other properties
Page | 27
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Simple gas faultfinding on appliances
Typical Gas Component Faults on Central Heating Boilers and
Circulators

Unsatisfactory Ignition Of Burners / Flame Supervision
Devices;
Flames not igniting,
Explosive ignition due to a range of possible faults;
Pilot flame to small
Pilot flame not in correct position
Faulty FSD
To much gas at the main burner
Not enough gas at the main burner

Unstable Flame Picture
Incorrect flame due to a range of possible faults
Over gassed (Long flames with possible yellow tips)
Lack of oxygen (Yellow flames)
Cracked burners
Blocked burners (Choked with soot)

Signs Of Spillage
Sooting in or around the appliance or appliance seals
Pattern staining from the draught diverter

Inoperative Thermostats
Inoperative operating thermostats giving temperature problems (to hot
or to cold)
If operating thermostat fails on a system boiler. The high limit stat will
lock the boiler out (requires to be manually reset)
If high limit stat also fails steaming hot water will discharge from the
pressure relief valve. This will drop the pressure from the boiler.
(requires to be manually reset)

Inoperative Air Pressure Switch
Symptoms on a fan flued boiler would be
The boiler fan starts up but the ignition sequence does not start
(The fan pressure switch starts the ignition sequence)

Inoperative Multifunction Control Valve
a multifunction control valve contains three main components
a FSD,
a Solenoid
a Regulator
all three components must work correctly.
Page | 28
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Typical Gas Component Faults On
Cookers

Unsatisfactory Ignition Of Burners / Flame Supervision
Devices;
Flames not igniting,
Explosive ignition due to a range of possible faults;
Pilot flame to small
Pilot flame not in correct position
Faulty FSD shut down in (90sec)
To much gas at the main burner
Not enough gas at the main burner
Faulty ignition system

Unstable Flame Picture at Full or Simmer
Incorrect flame due to a range of possible faults
Over gassed ( Long flames with possible yellow tips)
Lack of oxygen (Yellow flames)
Cracked or warped burners
Blocked burners (Choked with grease)

Faulty Thermostat or Oven By-pass
Thermostat out of calibration and undercooking or overcooking food
Oven burner goes out when the oven reaches temperature (blocked
by-pass)

Stiff Burner Control Tap
A control tap that is too loose or too tight may require re-greasing
A control tap must also lock itself in the off position so that it cannot be
turned on by accident check the spring and locking collar

Inoperative Lid or Grill Door Closure Device
Lid safety Device must turn the gas of to the burners
when the lid is lowered or grill door is closed.
Some devices turn all the gas taps off others have a reset button to
push when the lid is lifted again. Check that the device operates
correctly
Page | 29
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Typical Gas Component Faults On
Space Heating (gas fires)
 Unsatisfactory Ignition Of Burners / Flame Supervision
Devices;
Flames not igniting,
Explosive ignition due to a range of possible faults;
Pilot flame to small
Pilot flame not in correct position
Faulty FSD
To much gas at the main burner
Not enough gas at the main burner

Unstable Flame Picture
Incorrect flame due to a range of possible faults
Over gassed ( Long flames with possible yellow tips)
Lack of oxygen (Yellow flames)
Cracked burners
Blocked burners (Choked with soot)

Signs Of Spillage
Sooting in or around the appliance or appliance seals
Pattern staining from the draught diverter

Incorrect position of fuel on the fuel bed
If the wrong size of radiant or the incorrect amount of coals are used on
a gas fire the result could be
Flame impingement
Incomplete combustion
In either case the burner will not operate correctly, with the appliance
becoming sooted

Inoperable or Stiff control tap
Check that the gas tap is easy to work and that it controls the full range of settings on
the appliance

Inoperative Air Pressure Switch
Symptoms on a fan gas fire would be
The boiler fan starts up but the ignition sequence does not start
(The fan pressure switch starts the ignition sequence)
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Typical Gas Component Faults On
Warm Air Units.
 Unsatisfactory Ignition Of Burners / Flame Supervision
Devices;
Flames not igniting,
Explosive ignition due to a range of possible faults;
Pilot flame to small
Pilot flame not in correct position
Faulty FSD
To much gas at the main burner
Not enough gas at the main burner

Unstable Flame Picture
Incorrect flame due to a range of possible faults
Over gassed ( Long flames with possible yellow tips)
Lack of oxygen (Yellow flames)
Cracked burners CRACKED HEAT EXCHANGER/
Blocked burners (Choked with soot)
NO RETURN AIR DUCT

Signs Of Spillage
Sooting in or around the appliance or appliance seals
Pattern staining from the draught diverter

Inoperative Thermostats
Warm air units have a low temperature thermostat this lets the burner
turn on and heat, the heat exchanger before the fan unit turns on.
and a high temperature thermostat this turns the burner off when the
heat exchanger gets too hot, but lets the fan keep running.
If it does not operate in this sequence then the thermostat(s) may be
faulty.

Faulty Heat Exchanger
Symptoms of a cracked heat exchanger would be
The flame picture is very poor (flames blown side ways)
Products of combustion entering all warm air ducting
Pilot flame blowing out.
Fail spillage test at burner.

Inoperative Multifunction Control Valve
a multifunction control valve contains three main components
a FSD,
a Solenoid
a Regulator
all three components must work correctly.
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Typical Gas Component Faults On
Instantaneous Water Heaters
 Unsatisfactory Ignition Of Burners / Flame Supervision
Devices;
Flames not igniting,
Explosive ignition due to a range of possible faults;
Pilot flame to small
Pilot flame not in correct position
Faulty FSD
To much gas at the main burner
Not enough gas at the main burner

Unstable Flame Picture
Incorrect flame due to a range of possible faults
Over gassed ( Long flames with possible yellow tips)
Lack of oxygen (Yellow flames)
Cracked burners
Blocked burners (Choked with soot)

Signs Of Spillage
Sooting in or around the appliance or appliance seals
Pattern staining from the draught diverter

Scaled Heat Exchanger
A scaled heat exchanger usually results in a noisy unit due to the
reduction in flow rate. Also may cause the appliance to over heat

Inoperative Air Pressure Switch
Symptoms on a fan flued boiler would be
The boiler fan starts up but the ignition sequence does not start
( The fan pressure switch starts the ignition sequence)

Defective Gas Valve Assembly
Will result in the main burner failing to light or the main burner
staying on after the water has been turned off.
The problem may be:
Defective Diaphragm
Blocked Venturi
Failure of the mechanism (push rod sticking)
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Volume and purge calculations for large installations
With pipework greater than 28mm or a meter bigger than a 6m³ capacity.
See www.gb-gas.co.uk for more details.
Installation volume
Purge volume
Meter type
Installation purge volume x 1.5
LENGTH 15mm
Multiply D by 1.5
LENGTH 22mm
LENGTH 28mm
LENGTH 35mm
Pipe volume m³
Multiply the lengths by the
volumes from table in orange
Fittings +10%
Multiply A by 1.1 to add the
10% on
Meter volume
A
E
B
If the purging volume is less than 0.02m ³
purging is conducted from the furthest
practical point well ventilated and no
source of ignition.
C
Look up the meter
volume
Total installation
volume
D
Add B and C together
If the volume is greater than 0.035m³ or the meter
capacity is greater than 16m³/hr then the (commercial)
IGE UP 1 or 1A document and qualification must be
used.
If the purging volume is greater than 0.02m
³ purging is conducted from the furthest
practical point and the appliance must be
continually ignited until a flame is
established.
Steel / stainless steel
Copper
15mm
½
0.00024 (m³)
15mm
0.00014 (m³)
20mm
¾
0.00046 (m³)
22mm
0.00032 (m³)
25mm
1
0.00064 (m³)
28mm
0.00054 (m³)
0.0011 (m³)
35mm
0.00084 (m³)
32mm 1¼
Type of meter
FOR VOLUME CALCS
Meter volume (m³) for pipe work
volume calculations
G4 / U6
0.008
U16
0.025
E6
0.0024
Page | 33
ALLOWABLE DROPS IN THE TWO
MINUTE TIGHTNESS TEST
PIPEWORK 28MM OR LESS
NO METER
8MB
E6 METER
8MB
U6 – G4 – R5 4MB
IF PIPE WORK GREATER THAN 28MM
IS FITTED
E6 METER
4MB
U6 – G4 – R5 2.5MB
U16 METER 1MB
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Pipe Sizing to BS6891:2015
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GAS REFERENCE PACKAGE 2016v2
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GAS REFERENCE PACKAGE 2016v2
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GAS REFERENCE PACKAGE 2016v2
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GAS REFERENCE PACKAGE 2016v2
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Notes:
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