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GAS REFERENCE PACKAGE 2010v2
Aim To Pass With Gb-Gas
GAS REFERENCE
PACKAGE
This document is free to download and copy from www.gb-gas.co.uk
1
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GAS REFERENCE PACKAGE 2010v2
Aim To Pass With Gb-Gas
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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BS 7967-3
APPLIANCE TYPE
Back boiler unit
CO/CO2 RATIO
Boiler
0.008
In combination with fire 0.020
Central heating boiler
0.008
Hot water circulator
0.010
Flued space heater
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
Any ratios above these readings maybe through, misuse, lack of maintenance, damage
or aging.
COMBUSTI
ON
ANALYSER
Natural gas
Co…. 21
O2… 4.8
Co2...8.9
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.
C
O
M
B
US
TI
O
N
A
N
A
L
YS
IS
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.
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 for carbon monoxide 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.
4. If there is no rise then proceed to test the appliance.
Room
sealed and
open flued
appliances
Operate the appliance at full rate until the CO reading stabilizes or begins to fall,
whichever occurs first.
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.
4
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GAS REFERENCE PACKAGE 2010v2
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Pipe work inspection See www.gb-gas.co.uk for more details.
Common faults found on the meter installation:
Valve handle
Valve handle drops On / off label
missing
to on position
missing
Incorrect or no
No emergency
No governor on
telephone number
procedures label
primary meter
Incorrect materials
at meter
Governor not
sealed
Common faults found on pipework installation:
No 10mm² bonding To close to electric To close to electric
within 600mm of
meters or outlets
cables or conduits
the meter
(150mm)
(25mm)
Incorrect sleaving
Incorrect materials Incorrect fittings
methods
used in pipework
used in pipework
Pipework
inappropriately
supported
Unsatisfactory
workmanship
Re-establishing gas supplies
This checklist should be conducted every time the gas has been turned off. Even if only conducting a
tightness test.
A visual check on the pipework installation
A visual check of the appliances should be made
Calculate the ventilation requirements for the installation
Test for soundness
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 5 x 0. 006m³ = 0.030m³
Purge volume = pipework length x volume of 1m length x 1.1 (for fittings) x 1.5 plus meter purge volume.
Eg 3 m of 35mm pipe plus a U16 meter... 3 x 0.00084 x 1.1x1.5 =0.004158 m³ + 0.030 m³ =0.034158 m³.
See page 26 or IGEUP1B FOR MORE DETAIL or visit gb-gas.co.uk
Material and nominal size of pipe
Steel / stainless steel
Volume of 1m length of pipe
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
Purge the remaining sections of the installation (light and detect method)
Re-light each appliance in turn checking that all user controls are
working satisfactorily
Check all open flued appliances for spillage
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
Soundness test
(No pressure drop or smell
allowed)
Test pressure
Test time
10mb
1 min
20mb
1 min
20mb
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
Soundness test
(record any drops here)
Test pressure
Test time
20mb
1 min
20mb
2 min
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 so you will have to spray all the inlet pipework 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. differences
20mb
1 min
Soundness test (record any drops here)
20mb
2 min
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 testpoints 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
Test pressure
Test time
10mb
1 min
20mb
1 min
(see information below)
20mb
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
8mb over 2min*
4.5 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 testpoints 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
Let-by test
for Meter
Control
Valve (A)
Reason
Test
pressure
Test time
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.
Let-by test
Release the regulator valve
for
pressure should increase
Regulator
slightly.
lock out (B) Open meter control valve and
observe.
Stabilisation Raise pressure to 19 mb close
meter control valve
To check if MCV is
passing, if greater than
(max 0.25mb) report to
supplier. To confirm
let-by spray LDF in
valve
Approx.
2-10mb
1 min
to check if regulator is
passing on lock out, if
greater than (max
0.25mb) report to
supplier
To allow for temp.
differences
Approx.
2-10mb
1 min
19mb
1 min
Soundness
test
(No discernable
pressure drop or smell
allowed)
19mb
2 min
Observe
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
8mb over 2min*
4.5 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 testpoints with leak detector fluid*********
8
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Ventilation
“When checking ventilation requirements always observe manufacturers instructions”
Calculate MAX NET heat input
Take MAX GROSS heat input from the
appliance DATA BADGE and by 1.1
OPEN FLUED
ONE Open flued appliance in a room
MAX net heat input
ONE Open flued appliance in a
compartment vented to outside
MAX net heat input
ONE Open flued appliance in a
compartment vented to a room
MAX net heat input
Advent
Top
Bottom
YES
*
*
Outside
-7kW
X 5cm²
*
X 5cm²
X 10cm²
*
*
X 10cm² X 20cm²
TWO Open flued appliance in a room
MAX net heat input
TWO Open flued appliance in a
compartment MAX net heat input
ADD two heat inputs together and
calculate as above
ADD two heat inputs together and
calculate as above
-7 kW
X 5cm²
TWO Open flued GAS FIRES in the
additional ventilation may not be
same room (less than 14kW)
required
Add heat inputs together and calculate as
TWO Open flued GAS FIRES in the
for one open flued appliance in a room
same room (greater than 14kW)
IF flue or spillage test fails additional ventilation is required
ROOM SEALED
ONE Room Sealed appliance in a room
MAX net heat input
ONE Room Sealed appliance in a
compartment vented to outside
MAX net heat input
ONE Room Sealed appliance in a
compartment vented to a room
MAX net heat input
FLUELESS APPLIANCES
COOKER
WATER HEATER
TUMBLE DRIER
OPENABLE
WINDOW OR
SIMILAR
YES
YES
YES
Top
Bottom
Outside
*
*
*
X 5cm²
X 5cm²
*
X 10cm²
X 10cm²
*
<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
100 CM²
100 CM²
0 CM²
0 CM²
0 CM²
* IF THE ROOM CONTAINS A DOOR TO OUTSIDE THEN A VENT IS NOT REQUIRED
MULTI- APPLIANCE SITUATIONS
SIMILAR flued appliances in a room
MAX net heat input
DISSIMILAR flued appliances in a room
Measuring ventilators
ADD two heat inputs together and
calculate as above
TAKE largest ventilation requirement
Calculate the free air area (measure the holes) the hole
MUST be from 5 to 10 mm and not closeable.
if answer is in MM² 100 to get CM²
9
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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
BURNER
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:
Cooker 3 hotplates.
Fire on full rate.
Boiler on full rate.*
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 27 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
IMPERIAL METER (ft³): E.G. U6
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.
1 revolution = 1ft³ of gas
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.
METRIC METER (M³): E.G. E6, G4
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
1
0
0
7
1
3
3
M³
First reading on meter
-
1
0
0
7
0
7
2
M³
Amount of gas used
=
0
0
0
0
0
6
1
M³
E6 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.
11
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Gas safety devices and Controls
See www.gb-gas.co.uk for more details.
1
Flame supervision devices or F.S.D s
Recognise
Thermoelectric 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
Bi-metallic strip FSD
Recognise
Found
Test
Loop of metal
Only found on hot water circulators
1. Light pilot and establish.
2. Turn pilot off time until burner
turns off
3
Vapor pressure FSD
Recognise
Small probe directly on oven
burner, burner lights on low flame
Only found in cookers
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
Found
Test
4
Flame rectification
FSD
(electronic ignition)
Recognise
Found
Test
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
*Manufacturers instructions may differ from the times stated above. *
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Thermostats
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Purpose: to control heat
Dial with numbers indicated
Mechanical
thermostat
(Vapor expansion)
Recognise
Mechanical
thermostat
(rod type)
Recognise
Found
Test
Old cookers and water heaters.
Heat up appliance gas should turn
down / or off (depending on
appliance)
Electric thermostat
Recognise
Found
Test
Dial with numbers indicated
Boilers etc
Heat up appliance thermostat
should turn the solenoid off
Found
Test
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
6
Solenoid
Purpose
Found
Test
An electrically operated gas valve
Boilers etc
1. Turn electricity on valve opens
2. Turn electricity off valve closes
7
Multi-function
control
Purpose
A collection of controls in one unit
Found
Test
Boilers etc
If the FSD, Regulator and solenoid
work then the multi-function
control is working.
8
Relay valve
Purpose
Found
Test
An automatic gas valve
Old boiler, commercial cookers
1. Weep gas of the top of the unit
and the burner should open.
2. Stop the weep and the burner
will go off.
9
Lid safety device
Purpose
Mechanical safety
cut off
Found
Test
To turn off the burners, when the
lid drops
Cookers, (hotplates)
1. Turn on gas tap to hotplate.
2. Lower lid and gas should turn
off
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10
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
11
Atmospheric
Sensing
Device
(ASD) (VSD)
Purpose
To close down the open flued
appliance automatically, if the
appliance and flue operate
incorrectly
All open flued appliances after 1998
1. light pilot.
2. Close air inlet hole and observe
flame (turn yellow)
Found
Test
12
Atmospheric
Sensing
Device / over heat
Thermocouple
interrupter
Purpose
Found
Test
13
Regulator
Purpose
Found
Test
14
Zero governor
Purpose
Found
15
Medium to low
pressure Regulator
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
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)
New fan flued room sealed
appliances
Test
1. Attach manometer to burner pressure test point
Turn appliance on when the fan comes on the
manometer reads negative pressure, quickly going to
positive pressure when the burner comes on.
Purpose
To lower incoming gas pressure from
2 bar to 21mb
Above the meter control valve, fitted
with a reset handle
Found
Test
1. make sure working pressure is 21mb
make sure the regulator lockout does not let-by
14
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Flame rectification / conductance
Sequence of events for an electronic ignition fan flued boiler
yes no
1 Demand on the system turns pump then fan on.
2 Fan turns on fan 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
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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
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)
16
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GAS REFERENCE PACKAGE 2010v2
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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
Action taken
Label used
Notice used
None
Fill in the NCS
section of
warning notice
form
Inform responsible person, and repair fault if
possible. Fill in (notice) and give copy to
responsible person
Inform responsible person, and repair fault if Warning label do
A.R.
not use
AT RISK possible. If not turn appliance off attach
(label) and fill in (notice) and give copy to
responsible person.
I.D.
IMEDIATELY
DANGEROUSE
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 A.R.
section of
warning notice
form
Fill in the I.D.
section of
warning notice
form
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
Catchment area too
small
Flue not sealed to the
appliance
Joints leaking
Catchment area not
sealed
Flue damaged
Catchment area has
letterbox opening
Flue upside down
Incorrect flue for
appliance
Signs of spillage
Joints not sealed
Flues not clipped
Bend no greater than
45
Terminal not high
enough through the
roof.
Flue too small for
appliance.
Copex liner not fixed
at the top or bottom
To close to
combustible material.
Copex not sealed to
appliance
Minimum of 600mm
between draught
diverter and first bend
Incorrect terminal
Incorrect material or
methods used.
Room sealed flues
Flue not sealed
Flue length to long
Appliance seals
damaged or missing
Flue damaged
Terminating in wrong
position.
Incorrect material or
methods used
17
No terminal guard
Appliance or flue
leaking.
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GAS REFERENCE PACKAGE 2010v2
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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 may not be necessary to turn the fan
on as the problems that may occur with back pressure are checked when
conducting a spillage test)
IMPORTANT
while completing the test;
Test the flue
from cold
↓
→
Pre-test with
a smoke
match
FAIL
Heat the flue
for 10 min and
retest
↓
↗
↓
Test with a
smoke pellet
Pre-test with a
smoke match
↓
↓
OK
Test with a
smoke pellet
All smoke must be drawn into the flue.
The smoke must terminate at the correct point.
The flue must not leak into any other flue, room or dwelling
→
FAIL
Heat the flue
for further 10
min and retest
↗
↓
Pre-test with a
smoke match
↓
↓
OK
Test with a
smoke pellet
→
FAIL
Heat the flue
for further 10
min and retest
↗
↓
Pre-test with a
smoke match
If the flue is
condemned it may
require repair or
cleaning further
investigation is
required. Follow
the unsafe
situations
procedures
→
FAIL
If heating the flue with a blow torch, it
may require as much as 30 min to heat
properly
↓
↓
OK
Test with a
smoke pellet
↓
OK
18
↗
CONDEMN
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GAS REFERENCE PACKAGE 2010v2
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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. Turn the extractor fans on in the room and test
4. Turn extractor fans on in any other room in the house and leave the door
between the rooms open. And re test
5. When testing a flue with a fan in the area test with the fan on and with the fan off.
IMPORTANT
Heat the
appliance for 5
minutes
while completing the test;
All smoke must be drawn
↓
Leave the
appliance on and
place smoke
match in the
desired area
↓
Is all the
smoke drawn
into the
appliance
→
FAIL
Heat the
appliance for
further 10 min
↓
↗
→
Leave the
appliance on and
place smoke
FAIL
match in the
desired area
↓
OK
into the appliance.
The appliance must be left
on at maximum setting.
↓
CONDEMN
↗
Is all the
smoke drawn
into the
appliance
↓
OK
19
If the appliance fails then
further investigation may be
required
The appliance may be;
1. Over gassed.
2. Sooted up.
3. Blocked flue or flue ways.
4. Bad flue design.
5. Faulty appliance.
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GAS REFERENCE PACKAGE 2008.1
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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 its 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.
D Below a gutter, or
sanitary pipe work
E Below the eaves
300 [#] 75 [@]
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
600
200
300
300
300 [#] 200
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.
20
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GAS REFERENCE PACKAGE 2008.1
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Minimum distance to terminal in millimetres
Balanced flue, room-sealed appliance
Fanned draught
(0-7 kW)
(>7-14 kW)
Natural
draught
300
600
(>14-32 kW)
1500
300
(>32-70 kW)
B Above an opening, air (0-32 kW)
brick, opening window, (>32-70 kW)
etc
C Horizontally to an
(0-7 kW)
opening, air brick,
(>7-14 kW)
opening window, etc
(>14-70 kW)
2000
300
600
300
300
300
300
400
600
300
300
300
A Directly below an
opening, air brick,
opening window, etc
300
300
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
POSSIBLE
EXTENSION
21
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GAS REFERENCE PACKAGE 2008.1
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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.
22
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GAS REFERENCE PACKAGE 2008.1
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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.
23
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GAS REFERENCE PACKAGE 2008.1
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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 Closure Device
Lid safety Device must turn the gas of to the burners when the lid is
lowered
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
24
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GAS REFERENCE PACKAGE 2008.1
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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 flued boiler would be
The boiler fan starts up but the ignition sequence does not start
( The fan pressure switch starts the ignition sequence)
25
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GAS REFERENCE PACKAGE 2008.1
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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
Pattelkj ;oinern 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.
26
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GAS REFERENCE PACKAGE 2008.1
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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)
27
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GAS REFERENCE PACKAGE 2008.1
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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
LENGTH 15mm
LENGTH 22mm
LENGTH 28mm
LENGTH 35mm
Pipe volume m³
Multiply the lengths by the
volumes from table 1
Fittings +10%
Multiply A by 1.1 to add the
10% on
A
Total pipe volume
B
Pipework purge volume
x 1.5
F
This is the same as B
G
Multiply F by 1.5
Meter volume
Look up the meter volume
Total installation
volume
C
Meter purge volume
(cyclic volume x5)
H
D
Total purge volume
J
Add G and H together
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.
Steel / stainless steel
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.
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
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.
FOR VOLUME CALCS
FOR PURGE CALCS B
Meter volume (m³) for pipe work
volume calculations
Meter cyclic volume x 5 =Meter purge volume in (m³)
G4 / U6
0.008
0.002 x 5
U16
0.025
0. 006 x 5 = 0.030m³
E6
0.0024
N/A
Type of meter
28
= 0.010m³
=0.0036m³
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GAS REFERENCE PACKAGE 2008.1
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Pipe work sizing
Resistance table:
Discharge in straight horizontal table x copper tube with 1.0 mb differential
pressure between the ends, for gas of relative density 0.6 (air = 1).
When estimating the gas flow rate in pipework of a known length this length
must be increased by 0.5 m for each elbow and tee branch fitted.
Draw a plan of your pipe routs SPLIT THE PIPE WORK INTO SECTIONS and number them 1,2,3,4
etc. details on the plan the number of actual or estimated elbows and tees required.
Appliance / appliances
A
1
2
3
4
5
6
M³/HR
GAS FLOW REQUIRED
THIS IS THE GAS RATE OF THE
APPLIANCES THAT THIS PIPE IS
FEEDING
Pipework
B
LENGTH (how many meters of pipe)
M
C
FITTINGS (0.5m for each elbow or
tee going round the corner)
M
D
ACTUAL LENGTH (add B+C
together)
M
E
ASSUMED PIPE DIAMETER
Make an assumption on the pipe
diameter or use the table to find a
diameter
MM
F
CHART ALLOWABLE LENGTH
Use diameter E in the table read to the
right until you find close to or just
M
greater than A. then run up to the top
of the table to find the allowable length
G
mb
PRESSURE DROP
Chart allowable length D divided by
the actual length F. if this is greater
than one you have divided the wrong
number first.
Total Pressure drop
Adding the pressure drops from the meter to the appliances and all pipework it passes must total less
than one to pass eg. (From the meter to the first tee). + (From the tee to the appliance) = must equal less
than 1mb. See www.gb-gas.co.uk for more details.
Meter to appliance 1
Meter to appliance 2
Meter to appliance 3
Meter to appliance 3
29