Noisy boiler or heating pipes

If your boiler or heating pipes are making hissing or banging noises, you should address the problem immediately. Ignore it and you might find yourself needing expensive repairs or even a new boiler.

Don't imagine that fixing a noisy boiler is as simple as wielding a spanner yourself. The majority of boiler problems require the skills of a Gas Safe Register approved heating engineer. But there are a few checks that you can perform – which won't endanger lives and could help you give an engineer more information about the nature of the problem.

Scale in the heating system

The build up of scale can cause 'hot spots', which produce steam bubbles that make a loud bang. The problem can be treated with a chemical descaler, found at most DIY stores.

This will involve:

  1. Shutting down the system
  2. Adding the product to the feed and expansion tank
  3. Leaving it to work for a few days
  4. Draining, flushing through and refilling the system

Boiler thermostat is set too high or is faulty

First, try lowering the boiler thermostat. Unfortunately, while this may stop the noise, it might also lower the radiator temperatures. If the boiler thermostat is faulty it will need to be replaced by a Gas Safe Register approved engineer.

Insufficient water flow to the boiler

There are a number of possible reasons why there isn't enough water getting through to your boiler, so you should check the following:

  • Water flow rate
    With modern, wall-hung, light-weight gas boilers, water flow rate is particularly important. Check that the mains water is on. If it is, check your feed and expansion tank (if you have them, they're usually found in the loft).
  • Float valve
    1. First, shut down your central heating boiler.
    2. Locate the tanks and double check that the float valve isn't stuck. If it is, you'll have to move its metal arm to release it.
    3. Check that the open safety-vent pipe is correctly installed. If not, air can get into the system, causing noise in the boiler. If this is the case, you'll need to enlist the help of a professional heating engineer.
  • Frozen water supply pipe
    If this doesn't work and it's currently very cold outside, then it's possible your water supply pipe may have frozen.

Lack of water pressure in your boiler

If the problem is a lack of water pressure, the pressure indicator on your central heating boiler will usually indicate that it needs to be increased.

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