Common home heating problems and how to fix them


Thermostatic radiator valve saves you cash


It’s murphy’s law that as soon as you need the central heating to work in your home at the first sign of winter, after a period of being out of use, then it will break down. It’s always a good habit to check up on your heating systems long before winter to make sure you’ll stay warm throughout the cold season. By doing this, you can schedule ahead for repairs, maintenance or even a boiler installation if necessary.

But instead of paying over-the-odds for a central heating engineer or plumber, it might be worth having a go at fixing it yourself first.

The most common problems home-owners are likely to face with their heating systems are as follows.


1) The radiators are cold at the top but warm at the bottom. This may be caused by air in the radiator, which can be rectified quite easily by bleeding it using a radiator key.

Loosen the nut, either at the top right or the top left of the radiator. Hold a towel or a piece of rag below the nut to catch any water seeping out of the radiator once it has been loosened.

Then, if there is air in the system, it will rush out with a hissing sound. If water starts to come out, immediately tighten the nut back up and the problem should be resolved.


2) If the radiators are cold at the bottom but warm at the top, this indicates there could be sludge in the radiator. Fixing this involves flushing out the individual radiator or the whole system.

If more than one radiator is affected, this may indicate a problem with the pump that circulates hot water around the system, (if so, a Grundfos selectric may be a good replacement), or it may be that there is sludge in the pipe work between the radiators.

If the heating system has been badly designed, you would probably be best advised to call in a certified heating engineer or a plumber experienced in domestic central heating systems.


3) If the radiators are cold but the water is still heating up, make a few checks yourself before calling out an engineer.

Start with the room thermostat or zone thermostats, and make sure they are set to between 17 C and 20 C.

If the radiators are still cold, go to your system’s control panel and check that both the central heating and the hot water are set to come on.

If they have been set, then check the diverter valve and the heating pump, although this may be something you would prefer to leave to the experts.

You could try turning off the electrical supply to the diverter valve and then switching it on again. If resetting it doesn’t work, call a heating engineer.

If the problem is with the heating pump it may just be that there is an air lock. Or, in the worst-case scenario, the pump may be broken.

Removing the air lock is relatively easy to fix by bleeding it. If this doesn’t work, the pump may have to be replaced. One of the most cost-effective is the Grundfos selectric, which retails for about £79.


4) If the boiler is making a strange noise, try turning the power off then switching it on again. The noise might be caused by the water heating up after the pilot light has come on.


5) If water is running out of the overflow, this could be due to a jammed or faulty ball-cock in the water tank. This may need to be adjusted or replaced.


If there is still a problem after looking at all the above, it might be time to seek the help of a professional – but at least you can let the plumber know what you’ve tried to help to make the process a lot faster. You may also be entitled to a free boiler, you can check your eligibility at, where you simply answer a few questions and get an answer in minutes.





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