Peter Lennard Heating Repairs & Servicing

Preliminary checks that can be carried out:

If you have a conventional boiler, with a hot water cyclinder:

(combi boiler? Click here)

1) Are there any danger signs?

2) Boiler sounds completely dead

3) Prepayment gas meter - has it run out of money?

4) Pilot out

5) Lockout (if boiler has electronic ignition)

6) Check the Pressure (if boiler has a pressure gauge - it probably doesn't)

7) Heating only works at the bottom of the house

1) Are there any danger signs? Smell of gas or fumes? Loud banging noises? Temperature gauge (if one is fitted) going higher than 80 degrees centigrade? If so do not attempt to relight/restart the boiler - it is safer to switch it off, and ring me. Back to top

2) Does the boiler sound completely dead when either the heating or hot water are switched on?There are a few possible reasons:

a) Are all the controls switched on? Timeclock on? Room thermostat turned up high enough? Turn it up to maximum just to test it. Has someone accidentally turned off the electricity to the boiler at the switch or plug on the wall?

b)  If you can't hear even a very slight hum or whirr and the boiler is completely silent one possibility is that the main fuse in the boiler's electricity supply has failed or someone has accidentally switched off the boiler's electricity thinking they were switching off something else, such as the fridge to defrost it or the washing machine. If the boiler's electricity has not been switched off accidentally then consider replacing the fuse which will be in the fused plug or spur. The correct fuse is three amps for a normal domestic gas central heating system, so never fit any fuse larger than that. If you fit a new 3amp fuse and it immediately blows then the boiler has a short circuit and should be left switched off and an engineer called out. Repeatedly changing the fuse will only risk damage to the boiler's electronic circuits or even ancilliary items such as the timeclock or room thermostat, if fitted.

c) If you've checked the above, then component failure somewhere is likely - ring me. Back to top

3) Do you have a prepayment gas meter - one of those with a rechargeable key? Has the gas run out? (Yes, I have been called out when the gas had run out). Back to top

4) If the boiler normally has a pilot, is it alight? If not, and you know how, and you have no reason to suspect any danger such as a smell of gas then it is normally OK for a user to relight the pilot. If the pilot is alight the problem can sometimes be cured by simply extinguishing the pilot and then relighting it a few minutes later. However, if you have not been shown how to do any of these things then it is better not to try now without guidance. Back to top

5)Lockout - if the boiler has electronic ignition (i.e. it never has a pilot) it may have gone to 'lockout'. The first time this happens it can be reset if you are familiar with the reset procedure. If the boiler repeatedly goes to 'lockout' it is faulty and must be repaired and should not be repeatedly reset. Back to top

6) Check that the pressure shown on the gauge marked 'Pressure' is correct. It should be between 1 and 1.5 bar when the radiators are cold (if the gauge is recording pressure in bars reading 1, 2, 3, 4 etc). Older boilers might display pressure on a gauge reading 10, 20, 30, 40 (mH2O) in which case the pressure should be between 10 and 15 when the radiators are cold. Back to top

7) If the heating only works at the bottom of the house it may be that the ball valve in the small Feed and Expansion tank has got stuck, in which case unsticking it by hand may cure the problem. Normally this tank measures only 18 inches by 12 inches, is rectangular and made of black plastic, and is sited in the loft. However, if you are unsure how this is done, don't try it in case it won't turn off and causes a flood. Always visibly check that the overflow pipe from this tank is securely in place, assuming it was installed in the first place!

Danger Signs - 1
Boiler sounds dead - 2
No money in gas meter - 3
Pilot out - 4
Lockout - 5
Pressure low - 6
Top of house cold - 7

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Peter Lennard, Vaillant, Viessmann & Vokera Specialist
020 8674 1166

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