Plumbing Advice – Gas boiler not working

General Plumbing

Plumbing advice – for guidance only


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PLEASE NOTE: It is illegal to work on a gas boiler if you are not qualified to do so. Never remove the casing to your boiler for access, or do work on anything to do with gas pipes, the boiler or the flue! The advice below does not involve working on your boiler and instructions for repressurising can be found in your manual.

It can be both expensive and inconvenient to call our a plumber, so if you are having problems with your boiler, then it may be worth checking out the following points before you do…

There are so many things that can go wrong with a boiler and stop it from working. But here are a couple of simple problems that a householder can sort out without calling out an engineer…

The first one occurs with condensing boilers during very cold spells. If the condense pipe leaves the boiler and passes through the wall to the outside, terminating into a drain or soil pipe etc. there is a good chance that the water inside the pipe has frozen up and blocked the flow from the boiler. If this happens then the boiler will shut down and not work. Try warming the outside condense pipe with hot water to free the ice and then restart the boiler.

The second simple, yet common, problem happens if you have a ‘systems’ boiler where the central heating water is sealed in a closed circuit and filled up by mains water via a filling loop. The boiler will have a pressure gauge and it should read 1.25bar to 1.5bar when cold. However if you have lost pressure and it is below 0.5bar then the boiler has a low water detector and will stop the boiler from working. The solution is… refilling the system via the filling loop to 1.25bar and restart the boiler.



PLEASE NOTE. These instructions are intended as a guide only. I can’t see the particular job you may be attempting so I can not give you definitive instructions. You undertake the work at your own risk and I accept no responsibility for the accuracy of these guidelines.

Your Local Gas Safe Plumbing & Central Heating Specialist