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Page | 2

Online Gas Training at www.gb-gas.co.uk.

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 ................................................................................................................................................. 21

Flue inspection .................................................................................................................................................... 21

Room sealed flues................................................................................................................................................ 21

FLUE TESTING ................................................................................................................................................. 22

SPILLAGE TESTING ....................................................................................................................................... 23

Spillage Testing for room sealed appliances ..................................................................................................... 24

Positive Fan Pressure ......................................................................................................................................... 24

Appliance list ....................................................................................................................................................... 24

Flue Termination Points..................................................................................................................................... 25

Condensation and pluming. ............................................................................................................................... 26

Typical Gas Component Faults on Central Heating Boilers and Circulators ............................................... 27

Typical Gas Component Faults On ................................................................................................................... 28

Cookers ................................................................................................................................................................ 28


Space Heating (gas fires) .................................................................................................................................... 29


Warm Air Units. ................................................................................................................................................. 30


Volume and purge calculations for large installations .................................................................................... 32

Pipe work sizing .................................................................................................................................................. 33

Notes: ................................................................................................................................................................... 34


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Hours of videos and quiz questions @ www.gb-gas.co.uk

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.

http://www.gb-gas.co.uk/


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Appliance testing BS 7967-3 APPLIANCE TYPE CO/CO2 RATIO

Back boiler unit 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

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. 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.

COMBUSTION

ANALYSER

Natural gas

Co…. 21 O2… 4.8

Co2...8.9

C

Most analysers work out ratios automatically. The

calculation is: 𝐶°/𝐶°2 𝑟𝑎𝑡𝑖𝑜 = 𝐶°

(𝐶°2 ×10,000)


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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.

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


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.

Flueless space heaters


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:

Valve handle missing

Valve handle drops to on position

On / off label missing

Incorrect materials at meter

Incorrect or no telephone number

No emergency procedures label

No governor on primary meter

Governor not sealed

Common faults found on pipework installation:

No 10mm² bonding within 600mm of

the meter

To close to electric meters or outlets

(150mm)

To close to electric cables or conduits

(25mm)

Pipework inappropriately

supported

Incorrect sleaving methods

Incorrect materials used in pipework

Incorrect fittings used in pipework

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.

1. A visual check on the pipework installation

2. A visual check of the appliances should be made

3. Visual check & Calculate the ventilation requirements for the installation

4. Test for Tightness

5. 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) x 1.5 plus meter purge volume. Eg 3 m of 35mm pipe plus a U16 meter... 3 x 0.00084 x 1.1 + 0.024 x1.5 =0.042 m³.

See page 32 or IGEUP1B FOR MORE DETAIL or visit gb-gas.co.uk

Material and nominal size of pipe Volume of 1m length of pipe

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)

32mm 1¼ 0.0011 (m³) 35mm 0.00084 (m³)

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



Page | 7


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

Test pressure Test time

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

7-10mb 1 min

Stabilisation to allow for temp. differences

20-21mb 1 min

Tightness test

(No pressure drop or smell allowed)

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

20-21mb 1 min

Tightness test

(record any drops here)

20-21mb 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 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. differences

20-21mb 1 min

Soundness test

(record any drops here) 20-21mb 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 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

7-10mb 1 min

Stabilisation To allow for temp. differences

20-21mb 1 min

Soundness test

(see information below) 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



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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

Test time

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.

To check if MCV is passing, if greater than (max 0.25mb) report to supplier. To confirm let-by spray LDF in valve

Approx.

7-10mb

1 min

Let-by test for Regulator lock out (B)

Release the regulator valve pressure should increase slightly. Open meter control valve and observe.

to check if regulator is passing on lock out, if greater than (max 0.25mb) report to supplier

Approx.

7-10mb

1 min

Stabilisation Raise pressure to 19 mb close meter control valve

To allow for temp. differences

19mb 1 min

Soundness test

Observe (No discernable pressure drop or smell allowed)

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



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Tightness testing Flow Chart

Raise greater than

0.25mb?

No discernable raise

or drop?

fall greater than

0.25mb ?

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

Tightness @ 20mb to 21mb

for 2 min

No discernible raise

or drop?

No discernible raise

or drop?

There may be a leak

in the system. This


complete the let by

test again

Fall greater than

0.25mb?

Fall greater than

0.25mb?

There may be a leak

in the system. ON NEW SYTEMS This


complete the let by test

again

EXISTING SYSTEMS

may pass if the drop is less

than the allowed limits

and no smell of gas

System passes

with no smell

of gas

Let by test @ 7-10mb for 1 min

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 4.5MB

U6 – G4 – R5 2.5MB

U16 METER 1MB


Page | 11


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 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

Max H.I. x 5cm2 top Max H.I. x 5cm2 bottom


IN A COMPARTMENT VENTED THROUGH THE ROOM


Max H.I. x 10cm2 top Max H.I. x 20cm2 bottom Vent to outside

Max H.I. – 7kw x 5cm2

IN A COMPARTMENT VENTED VIA A ROOF SPACE

There are many allowable configurations of top and bottom ventilation. Consult the Manufacturer’s instructions

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

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


Page | 12


OPEN FLUED additional

TWO Open flued GAS FIRES in the same room (less than 14kW)

additional ventilation may not be required

TWO Open flued GAS FIRES in the same room (greater than 14kW)

Add heat inputs together and calculate as 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 100cm2 for first then 135cm

2 for each additional

(extra 35cm2 is adventitious ventilation ie 7kw)

= 235cm2 for two DFE fires.

FLUELESS APPLIANCES OPENABLE WINDOW OR

SIMILAR

ROOM SIZE (M³)

<5 5-10 10-15 15-20 >20

COOKER YES 100 CM² 50 CM² * 0 CM² 0 CM² 0 CM²

WATER HEATER YES NOT 100 CM² 50 CM² 50 CM² 0 CM²

TUMBLE DRIER YES <3.7m³/kW =100cm² >3.7m³/kW =0cm²

SPACE HEATERS YES 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 Find the largest requirement from the three rules below

All Open flued Space Heating………. or

ADD heat inputs together and calculate

All flueless Space Heating…………… or

Add all vents sizes together

Biggest of any other appliance TAKE largest ventilation requirement

Measuring ventilators

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

Length

Width

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

The Radius is

half the circle

Trapezium Formula = Length x Width x Number of holes.

Example: 4cm x 0.8cm x 30 holes = 96 cm2


Page | 13


Pressure testing

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 29 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*********

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)

APPLIANCE INLET

WORKING PRESSURE

(max 1mb drop form working

pressure at the meter)

APPLIANCE BURNER

PRESSURE (check

against appliance data

badge)

Multifunction control


Page | 14


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 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.

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. See website for details



Page | 15


Gas Rate Tables


Page | 16


Gas safety devices and Controls See www.gb-gas.co.uk for more details.

Flame supervision devices or F.S.D s

Purpose : To avoid unlit gas entering the appliance

1 Thermoelectric FSD

Recognise because it has a push button and thermocouple

Found in every type of gas appliance

Test 1. Light pilot and establish. 2. Turn gas off time until click

2 Bi-metallic strip FSD

Recognise Loop of metal

Found Only found on hot water circulators

Test 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

Found Only found in cookers

Test 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)

4 Flame rectification FSD

Recognise Ignition starts automatically to light the pilot or main burner

(electronic ignition)

Found On all appliances

Test 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 60 SEC * W / AIR HEATERS 60 SEC * COOKERS 90 SEC oven

60 SEC other * WATER HEATERS 90 SEC * D.F.E. GAS FIRES 120 SEC * OTHER GAS FIRES 180 SEC * *Manufacturers instructions may differ from the times stated above. *



Page | 17


Thermostats Purpose: to control heat

4 Mechanical thermostat

Recognise Dial with numbers indicated

(Vapor expansion) Found Mostly on cooker ovens

Test 1. Turn oven on and heat up for 15 min.

2. Turn control to lowest setting flame should drop to by-pass rate

Mechanical thermostat

Recognise Dial with numbers indicated

(rod type) Found Old cookers and water heaters.

Test Heat up appliance gas should turn down / or off (depending on appliance)

5 Electric thermostat Recognise Dial with numbers indicated

Found Boilers etc

Test Heat up appliance, thermostat should turn the solenoid off or modulate the burner pressure down

6 Electronic thermostat

Recognise Electronic PCB Appliances

Found Combi, Water Heaters, Condensing Boilers etc.

Or Thermistor Test Heat up appliance, the thermistor will modulate the gas pressure to the burner, or the fan Approx. 11 -13 kΏ at room temperature

7 Solenoid Purpose An electrically operated gas valve

Found Boilers etc

Test 1. Turn electricity on valve opens 2. Turn electricity off valve closes

8 Multi-function control

Purpose A collection of controls in one unit

Found Boilers etc

Test If the FSD, Regulator and solenoid work then the multi-function control is working.

9 Relay valve Purpose An automatic gas valve

Found Old boiler, commercial cookers

Test 1. Weep gas of the top of the unit and the burner should open.

2. Stop the weep and the burner will go off.


Page | 18


10 Lid or Grill Door safety device

Purpose To turn off the burners, when the lid drops

Mechanical safety Found Cookers, (hotplates)

cut off Test 1. Turn on gas tap to hotplate. 2. Lower lid or close grill door and

gas should turn off

11 Gas tap Purpose To control the flow off gas safely

Found Cooker, fires ,etc

Test 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

Test 1. Light pilot. 2. Close air inlet hole and observe

flame (turn yellow)

13 Atmospheric Sensing Device / over heat

Purpose To close down the open flued appliance automatically, if the appliance and flue operate incorrectly

Thermocouple interrupter

Found On water heaters, Flued water heaters this is usually a overheat safety device. Flueless used as an ASD

Test Visual inspection to check wiring to thermocouple (no links) and check FSD

14 Regulator Purpose Adjuster screw to alter burner pressure

Found Boilers etc

Test 1. Attach manometer to test point 2. Adjust screw to alter pressure

15 Zero governor on a atmospheric burner

Purpose To compensate for the negative pressure caused by the fan, on the gas valve (this could pull more gas into the burner than intended)

Found Fan flued room sealed appliances with atmospheric burners

Test 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.


Page | 19


16 Zero governor on a Pre Mix burner

Purpose 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)

Found Fan flued room sealed Condensing appliances with Pre Mix burners

Test 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

17 Medium to low pressure Regulator

Purpose To lower incoming gas pressure from 2 bar to 21mb

Found Above the meter control valve, fitted with a reset handle

Test 1. make sure working pressure is 21mb make sure the regulator lockout does not let-by

See MOP Tightness testing sheet for a full test

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

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


Page | 20


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

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


Unsafe situations

To find out if a situation is NCS AR or ID consult the unsafe situations document

Category Action taken Label used Notice used

N.C.S. NOT TO

CURRENT STANDARDS

Inform responsible person, and repair fault if possible. Fill in (notice) and give copy to responsible person

None Fill in the NCS section of

warning notice form

A.R. AT RISK

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.

Warning label do not use

Fill in the A.R. section of

warning notice form

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 I.D. section of

warning notice form

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 Catchment area too small

Catchment area not sealed

Catchment area has letterbox opening

Incorrect flue for appliance

Flue not sealed to the appliance

Flue damaged Flue upside down Signs of spillage

Joints leaking Joints not sealed Flues not clipped Minimum of 600mm between draught diverter and first bend

Bend no greater than

45

Flue too small for appliance.

To close to combustible material.

Incorrect terminal

Terminal not high enough through the roof.

Copex liner not fixed at the top or bottom

Copex not sealed to appliance

Incorrect material or methods used.

Cement lined flues must have a completion certificate; New Chimneys must have a data badge attached in the catchment area.

Room sealed flues Flue not sealed Appliance seals

damaged or missing Terminating in wrong position.

No terminal guard

Flue length to long Flue damaged Incorrect material or methods used

Appliance or flue leaking.

SE Duct U Duct and other shared flue systems must not be altered unless it can be certificated on completion. Multi duct systems for Fan flued appliances must be installed as per the manufacturer, alterations must be certificated.

All flues in ducts or ceiling voids must have access for inspection… minimum size for hatch is 300mm x 300mm and placed within 1.5m of a joint in the flue (1 hatch could service three joints)


Page | 22


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)

Test the flue

from cold

IMPORTANT while completing the test;

*All (the majority of) 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

Pre-test with a smoke match

Heat the flue for 10 min and retest

Test with a smoke pellet


Heat the flue for further 10

min and retest

OK



Heat the flue for further 10

min and retest

OK



CONDEMN

OK


OK

If heating the flue with a blow torch, it may require

as much as 30 min to heat properly

If the flue is

condemned it

may require

repair or

cleaning

further

investigation

is required.

Follow the

unsafe

situations

procedures

Lengt

way



Page | 23


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.

Heat the appliance for 5

minutes

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.

Leave the appliance on

and place smoke match in the desired area

Heat the

appliance for further 10 min

Is all* the smoke drawn

into the appliance

Leave the appliance on

and place smoke match in the desired

area

CONDEMN

OK Is all* the smoke drawn

into the appliance

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.

OK

o

Test



Page | 24


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 Manufacturer and Model Manufacturer and Model

Alde International (UK) Ltd Glynwed Domestic & Heating (cont.) Myson (Thorn) Olympic 38/50F

Alde 2927 Slimline Highlight P50 Myson (Thorn) Apollo Fanfare 15/30

Highlight P50A SC Myson (Thorn) Apollo Fanfare 30/50

Brassware Sales Ltd Highlight P50S Supaheat 50/15 with “A” control

Ferrolli 76FF Highlight P50SS Supaheat GC 50/15

Ferrolli 77FF Highlight P50S/A Netaheat MkI 10/16

Highlight P50S/A GLC Netaheat MkI 16/22 BF

Crosslee (JLB) (Pyrocraft) Highlight P50S/A SC Netaheat MkII 10/16 BF

AWB 23.09 WT Combi Highlight P50/A Netaheat MkII 16/22 BF

Highlight P70 Netaheat MkIIF 10-16 BF

Crosslee (Trisave Boilers Ltd) Highlight P70S Netaheat MkIIF 16-22 BF

Trisave Turbo T45 Highlight P70SS Netaheat Electronic 6/10

Trisave Turbo T60 Netaheat Electronic 10/16

Trisave Turbo 30 Halstead Heating & Engineering Ltd Netaheat Electronic 16/22

Trisave Turbo 22 Halstead 45F Netaheat Electronic 10/16e

Halstead 55F Netaheat Electronic 16/22e

Glow-worm Ltd Halstead 65F

Economy 30F Wickes 45F Stelrad Group Ltd

Economy 40F Wickes 65F Ideal Elan 2 40F

Economy 50F Barlo Balmoral 45F Ideal Elan 2 50F

Glow-worm Fuelsaver 35F Barlo Balmoral 55F Ideal Elan 2 60F

Glow-worm Fuelsaver 45F Barlo Balmoral 65F Ideal Elan 2 80F

Glow-worm Fuelsaver 55F Harvey Habridge Ltd Ideal Excel 30F

Glow-worm Fuelsaver 65F Impala MkII Ideal Excel 40F

Glow-worm Fuelsaver 80F Impala MkII Ridgeseal Ideal Excel 50F

Glow-worm Fuelsaver 100F Impala Ideal Excel 60F

Impala Super 2 (VF) Ideal Sprint 80F

Glynwed Domestic & Heating Ideal W2000 30F

AGA A50 Potterton Myson Ltd Ideal W2000 40F

AGA A50 A Netaheat Profile 30e Ideal W2000 50F

AGA A50 NG Netaheat Profile 40e Ideal W2000 60F

AGA A50 SS Netaheat Profile 50e

AGA A50 ANG Netaheat Profile 60e Worcester Bosch

AGA A60 Netaheat Profile 80e Heatslave 9.24 RSF

AGA A50 NG Netaheat Profile 100e Worcester 9.24 Electronic RSF

AGA A75 NG Myson (Thorn) Olympic 20/35F Worcester 9.24 Electronic RSF ‘S’



Page | 25


Flue Termination Points

Distances Natural draught

Fan draught

D Below a gutter, or sanitary pipe work

300 [#] 75 [@]

E Below the eaves 300 [#] 200

F Below a balcony or carport roof

600 200

G Above ground, roof or balcony level

300 300

H From vertical drain/soil pipe work

75 [@] 75 [@]

J From an internal or external corner

600 300

K From a surface or boundary facing the terminal

600 600 [+]

L Vertically from terminal on same wall

1500 1500

M Horizontally from terminal on same wall

300 300

N From a terminal facing the terminal

600 1200

P From an opening in a carport (e.g. door, window) into the building

1200 1200

R From a vertical structure on the roof [Note $]

n/app n/app

S Above an intersection with the roof

n/app n/app

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

(0-7 kW) 300 300

(>7-14 kW) 600 300

(>14-32 kW) 1500 300

(>32-70 kW) 2000 300

B Above an opening, air brick, opening window, etc

(0-32 kW) 300 300

(>32-70 kW) 600 300

C Horizontally to an opening, air brick, opening window, etc

(0-7 kW) 300 300

(>7-14 kW) 400 300

(>14-70 kW) 600 300

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.


Page | 26


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


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


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



Space Heating (gas fires)



Incorrect flame due to a range of possible faults Over gassed ( Long flames with possible yellow tips) Lack of oxygen (Yellow flames) Cracked burners


Signs Of Spillage


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


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)


Page | 30



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


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


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.


Page | 31



Instantaneous Water Heaters



Incorrect flame due to a range of possible faults Over gassed ( Long flames with possible yellow tips) Lack of oxygen (Yellow flames) Cracked burners


Signs Of Spillage


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


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)


Page | 32


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 in orange

A Installation purge volume x 1.5 Multiply D by 1.5

E

Fittings +10% Multiply A by 1.1 to add the 10% on

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.

Meter volume Look up the meter volume

C

Total installation volume Add B and C together

D

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)

32mm 1¼ 0.0011 (m³) 35mm 0.00084 (m³)

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


Pipe work sizing

Resistance table for copper pipe only: 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 1 a-b 2 b-c 3 b-d 4 5 6

A GAS FLOW REQUIRED THIS IS THE GAS RATE OF THE APPLIANCES THAT THIS PIPE IS FEEDING

M³/HR

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 greater than A. then run up to

the top of the table to find the allowable length

M

G 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.

mb

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




a-c

a-d



Page | 34


Notes:

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