Heating SOS – Diagnose a heating system fault

Your boiler plays a vital role in making your home a comfortable place to live. By providing hot water and central heating, your boiler is integral to the running of your home, yet it is one of the easiest appliances to take for granted. That is, until something goes wrong. Common boiler issues can be easy to diagnose and a small amount of knowledge on the subject could save you from heating SOS.

Diagnosing Boiler Noise

If your boiler emits a clunking sound (known as kettling) this could be due to a build up of scale in the heat exchanger. This scale is caused by hardness salts within the water which precipitate on the exchanger surface and act as an insulator, creating ‘hot spots’. The clunking sound occurs when these ‘hot spots’ produce steam bubbles.

When left untreated the scale will lower your boiler’s efficiency, just 0.8mm of scale can cause up to 8% heat loss and increase fuel consumption by 2%. In extreme cases a build up of scale could cause the exchanger to overheat and rupture.

During the winter months, boiler lockout on a condensing boiler could indicate that the condensate pipe, which transports condensed water vapour away from the boiler, is frozen. This is assuming the pipe terminates outside of the house. It is best to ask a qualified engineer to fix this issue for you. However, if the pipe is at ground level, and you know what you are doing, you can thaw this yourself using heat wraps or a hot water bottle.

A whistling noise from within your boiler could be caused by kettling or trapped air within your heating system. If the problem is down to trapped air, this can be resolved easily by a boiler engineer who will release the air. They will then be able to investigate how the air got drawn into the system, such as through a defective valve or a pressure leak, and make any necessary repairs.

Diagnosing a Boiler Leak

A boiler leak could be the result of a number of different issues which can usually be diagnosed by identifying the source of the leak, however if a gas boiler is leaking, you should not attempt to repair it yourself; gas boiler repairs should only ever be conducted by Gas Safe Registered engineers.

Common boiler leak issues include:

1. Temperature Valve – If the temperature valve is leaking it could be a sign that your boiler temperature is too high. It may be that the temperature probe, which ensures accurate temperature control of the hot water, is faulty and needs to be replaced.

2. Pressure relief valve – A leaking pressure relief valve is a sign that either the boiler pressure is too high (check expansion vessel) or the valve may have sediment preventing it from closing up. This high pressure could also be caused by a build up of limescale or debris.

3. Corrosion – The leak could be as a result of corrosion, which has resulted in metal wastage and allowed water to escape. You may be able to pinpoint a single corroded component which needs replacing, however, corrosion could be taking place across the whole of heating system and should be checked.

Diagnosing Loss of Boiler Pressure

Constant water pressure is essential for efficient boiler operation, so pressure loss causes the boiler to stop functioning. Most boilers have a pressure dial which will show you whether the pressure is too low; if this is the case it may be an issue which is easy to fix yourself.

It is possible that the system needs to be re-pressurised. The instructions on how to do this will be in the user manual and this is usually a relatively simple process involving re-pressurising the system by adding fresh water. If this does not resolve the problem or if you have any doubts, you should call out an engineer.

A leak may be causing the loss of pressure and if this is the case you may notice damp patches around the central heating fittings or on the ceiling. You can fix the leak yourself if you are confident in doing so but if not you are at risk of making the issue worse or putting yourself in danger. In this case it is always best to call out an engineer to carry out the repairs.

A faulty pressure relief valve could also be causing a drop in boiler pressure. When the valve lifts it releases the system pressure resulting in a low pressure lock out of the boiler. This fault could be caused by corrosion debris preventing the valve from closing properly, weakening with age or splitting, in this instance it is important that you replace the damaged valve.

Once you have diagnosed the issue with your boiler you can decide whether it is something that you can safely fix yourself, if in any doubt you should always call out an engineer. Keeping your boiler and pipe work clean will limit the number of boiler problems that you encounter and keep your boiler functioning efficiently for longer.

Author Bio

Sasha Davison is a digital content writer for Sentinel, an international provider of lifetime protection products and services for heating and hot water systems. Sentinel offer a full range of products supported by experts to achieve best practice protection for domestic and commercial systems.