Why Is My Boiler Making Loud Noises?

Unusual noises in your pipes can be a sign of 'kettling' which is a result of a buildup of limescale within the heat exchanger and can cause ongoing issues in your central heating system. These noises can also be heard if you have low water pressure or a pump failure.

If you react quickly to these signs then the steps to fix the issue could be less complicated and more cost-friendly, you could even save the need for a new boiler.

You will need to call in a Gas Safe heating engineer to repair the issue, but here are some steps you can take to discover the root of the problem first.

Limescale in your heating system

If your boiler is making a loud banging noise, it could be a cause of steam bubbles produced by a build-up of scale. Limescale can be considerably damaging and have a significant impact on the lifespan and energy efficiency of a central heating system. It causes 'hot spots' which are generally treated with a chemical descaler.

How to use a chemical descaler:

1. Shut down the system
2. Add the product to the feed and expansion tank and leave it for a few days
3. Drain, flush and refill the system

Faulty or incorrectly set thermostat

A noisy boiler could be caused by having your thermostat set too high. To stop your boiler making noise, you could try lowering the temperature on your thermostat. Although your home might not be as warm as you'd like, the level of noise from your boiler should quieten.

Insufficient water flow

Poor water flow can often be to blame for boiler noise. Here’s how you can investigate this potential cause further:

1. First of all, you should check that the mains water is switched on. The feed and expansion tank (usually found in the loft) should also be checked if the mains water is switched on.
2. The float valve can be examined by turning off the power supply to the boiler and then make sure that the float valve isn't stuck in the tanks. If you find that the valve is stuck, be sure to reposition its metal arm to release it. 
3. Cold weather can result in frozen water pipes which can cause the noises in your central heating system.

Insufficient water pressure

A lack of water pressure can sometimes cause your boiler to make noises. Check the pressure indicator on your boiler and increase if necessary. Find our guide on how to re-pressurise your boiler here.

Boiler repairs should by law always be carried out by a qualified and Gas Safe engineer, so you should never attempt to carry out any repair work on your boiler yourself. Go to Service & Repairs to book an appointment with one of our expert engineers or give us a call on 0203 805 4581 .