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Common boiler faults.

Common Boiler Faults

So, you have a fault with your boiler? Don't panic, here's a simple guide to understanding what's going wrong. We have compiled the most common faults we have to deal with. You may even be able to fix some of these yourself, however, it is important to know when to call a professional.

No heating but you do have hot water.

Ok so we know your boiler should give you both heat AND hot water, but it's stopped the heat part! Nightmare!

The most common cause of this is a problem with the thermostat, check it, make sure it is on and working - after all it should be controlling the temperature! Failing this, you can try adding pressure to the boiler if you are confident you know how - if not, then it's time to call a professional.

Sometimes you have hot water but no heat.

There are a number of different things that could be going wrong here - like an airlock for example, or maybe one of the motorised valves is playing up. This is the type of problem you should call a qualified engineer about - give us a ring on 01506 444161, one of our gas safe engineers can help you - safely!

Are you finding that there’s no heat or hot water?

Again, there could be a number of different reasons for this. An error code displayed at help you identify the problem, although often these can be confusing - they will, however, be useful to a trained engineer. The reasons can vary from fuel not reaching the boiler (especially applicable if it’s an oil type boiler), the thermostat settings not working or set appropriately, the pipes are frozen due to adverse weather, low boiler pressure, or a pilot light may have gone out if you have an older one.

Noisy boilers.

Noisy boilers can be bothersome with their gurgling, whistling, and banging. It can be down to anything from a build-up of sludge, components coming loose, loose pipework, or malfunctioning electrical components and blockages.

Vibrating noises

A boiler that’s making vibrating noises could be the result of loose brackets that need tightening. You’ll be able to tighten the brackets yourself, but a Gas Safe registered heating engineer will need to diagnose the issue if this doesn’t stop the vibrating noises.

Loud banging noises

If your boiler is making loud banging noises, it may be the result of a faulty thermostat or a build-up of debris on the boiler’s heat exchanger. If there is a build-up of debris, you’ll need a qualified professional to carry out a power flush. A power flush removes the sludge in your system, preventing blockages and heating inefficiency.

Gurgling noises

Gurgling radiators could be the result of trapped air in the system, low water pressure, or a frozen condensate pipe. It is fairly common for a small amount of gurgling within the boiler, however it’s important to investigate further if this becomes loud or constant. There are simple fixes that can be carried out at home yourself, depending on the issue.

Read more below to diagnose the problem:

  1. Check if the system needs bleeding If there is trapped air in the system causing the gurgling you could bleed the radiators to release this air. Leaving trapped air in the system could lead to further troubles, so it’s best to deal with it straightaway.

  2. Check the water pressure Check the pressure gauge on the boiler in case you have low water pressure causing the gurgling noise. Always refer to your user manual, but typically if the reading on the display is below 1 bar, this is a sign of low pressure.

  3. Check for frozen pipes You can usually locate your boiler’s condensate pipe outside of your home, it’s usually a white overflow pipe. You should be able to thaw it with some warm water - not boiling.

Remember, if you are unsure, call us on 01506 444161.


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