How to fix a broken boiler

Our Top Most Common Boiler and Central Heating Problem


Your boiler is one of the hardest working appliances in your home as it’s the engine that works hard all year providing you with heating and hot water and it’s working especially hard at the moment with the extended winter we are having.


It quietly goes about its job every day helping keep you warm, comfortable and clean. In fact it’s only when our comfort is disrupted and when things start to go wrong that we give it much thought at all. But it’s inevitable that at some point that a fault will develop and it’s fair to say this is more likely to happen during the winter, the coldest and most inconvenient time of the year.


It’s annoying when any of our larger electrical appliances break down but a malfunctioning or broken boiler can cause untold misery and chaos within your household. But a cold home and cold bath in winter is something you’ll definitely want to avoid.


It’s no coincidence that boilers are more prone to breakdowns during the cold winter months due to the fact that they will have been relatively inactive over the warmer months. This sudden demand as it's forced back into life inevitably puts a considerable strain on your heating system. 


A boiler breakdown is an expensive inconvenience no matter what time of year; however some common boiler problems can be addressed without the need to call in a heating engineer. By asking a few simple questions I sometimes even manage to get my customers to resolve problems over the phone but the reality is the majority do require the services of a qualified and experienced professionals like Conduction (uk) Ltd.


If in doubt, it’s always best to seek professional help from a reputable Gas safe engineer. So from flashing lights, worrying noises to leaks, drips and intermittent faults I have listed below the top most common boiler problems I encounter. This list should guide you on what to look out for:


No heat or hot water

Though this may seem disastrous it’s actually a very common problem. Possible causes range from an airlock, broken diaphragms, to failure of motorised valves. Additionally issues with the thermostat or low water levels could also be contributory factor.


Loss of pressure

A water leak in the system is the most common reason for a loss of pressure however it could also be down to the pressure relief valve, which in turn is caused by the expansion vessel failing. By replacing the pressure relief valve and recharging the expansion vessel with air this problem can be rectified.


Rise in pressure

The expansion vessel failure, plate heat exchanger failure and filling loop/link valve passing may all cause a rise in pressure.


Leaking and dripping

It will depend on where the water is leaking from to determine what is causing the problem as this could be caused by a number of issues.


Banging noise

Banging, whistling, gurgling, yes central heating systems can make some very strange noises.  But when it becomes a nuisance and starts to give cause for concern its time to take action. A number of factors could be causing the problem such as air in the system is a common cause or it might be that the water pressure is too low or its kettling (see below).


Frozen condensation pipe

Most modern energy efficient boilers have a condensation pipe the purpose of which is to transports water away from the boiler.  Unfortunately this can  freeze up in prolonged periods of extremely cold and icy weather, causing a blockage which results in the boiler breaking down.


Thermostat problems

Older thermostats have the potential to develop a fault such as randomly turning the heating on/off, misreading temperature setting and losing accuracy.  Recalibration and cleaning of thermostat can be done but generally it would be sensible to invest in a newer, more energy efficient one.


Pilot light going out

Broken thermostat is a common cause of this problem as it will be affecting the gas supply to the pilot light.  Alternatively it could be down to a draught blowing the pilot light out due to a broken air seal or deposit build up in the pilot light which consequently needs cleaning.


No heat in radiators

Hot water failing to circulate around your heating system could be due to a defective pump.  However it could also be caused by a build up of sludge in your system which is preventing the hot water circulating around the system and reaching your radiators.  Chemically cleaning and power flushing your heating system will remove this build up allowing the free flow of hot water.



This is a common issue if you live in an area that has hard water as lime scale can build up on your boiler’s heat exchange. Build up of lime scale can result in steam bubbles being produced which can be responsible for the banging noise, so if you do start to hear a strange noises this may be a result of kettling.


Boiler keeps switching itself off

A number of the issues outlined above could explain this from problems with the thermostat, lack of water flow due to a closed valve, air or the pump not circulating the water in the system properly. Also low water pressure (check the gauge to make sure the pressure is correct)


Most people will not be confident enough to tackle a boiler and heating problem themselves so rather than postponing the inevitable you need to find yourself a competent Gas safe, Oftec or HETAS engineer.


If you’ve lucky enough to have a reliable trustworthy engineer already think yourself lucky.


The plumbing & heating industry doesn’t have the best reputation and understandably homeowners are very wary of being ripped off. Make sure you ask what costs are involved, is there a call out charge, do you have to pay for the collection of parts and what’s the cost of the return visit to fit the part. It’s worth asking if you will charged a premium for emergency call out as it could work out cheaper if you can wait a day or two. 


You can find out more about our breakdown and repair service and pricing on our web site or give us  a call on 01332 512769.

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