boiler noisy woman holding hands over ears

Why Is My Boiler Noisy?

Why is my boiler noisy? There are numerous reasons that a boiler or central heating starts to produce unwanted rattles, knocks, squeaks, etc. In fact, there are so many potential issues we have split this blog into three parts, just to make it easier to digest.This is a very common fault we call engineers out to solve. As you know, your central heating boiler is the source of heat for your home. It requires input from three elements to make it work: fuel, such as gas or oil; electricity, to power the components; and water to transfer the heat around the heating system from your boiler (radiators, underfloor heating etc.). There is a lot ensuring these three supplies work safely and efficiently. In this blog, we will look at the common causes associated with fuel for these irritation noises, and suggest the best course of action you can take to solve the issue.

>>>>>> For water related noises, read our blog here <<<<<<

>>>>>> For electrical related noises, read our blog here <<<<<<

Why is my boiler noisy? Burning Fuel

Below is a list of unwanted sounds and potential causes produced by a noisy boiler.

  • Sloshing of water sound – condensate
  • High pitch squealing – pump
  • Chugging noise – sludge
  • Boiling – restriction/blockage
  • Rattling – case
  • Knocking – scale
  • Chattering – gas valve
  • Hooting – fan/flue issues
  • Crackling – short circuit
  • Ticking – ignition
  • Creaking – bearings,
  • Clanking – fan
  • Buzzing/Humming – gas valve, div valve, fan, pump

Natural gas fuels the common boiler in the UK, so for ease of explaining potential noise problems, we will use gas as an example. Oil and solid fuels may have other noise issues not related to this blog.

First up, it is worth noting there is little you can do personally if there is an issue with the gas causing unwanted noise to occur. You will need the expertise of a Qualified Gas Safe Engineer. However, if you understand the process, it can help resolve the issue quicker.

Gas feeds into your meter via a regulator. This governs the flow of gas to ensure a stable flow of gas and protects gas components in your property. Although a rare problem, the regulator can start to cause issues with the supply, which in turn can lead to the boiler making storage noises. Engineers will pick up the issue through their essential tests.

Inside the boiler

Gas flows from a meter to the boiler via gas pipework to a manual isolation valve under the boiler. Another highly unlikely issue is tinkling noise from any debris inside the pipe. Again, all work requires expert help. In most cases, we leave the isolation valve turned on, so no problems with noise here. Get inside the boiler and this is where we find most gas related potential noisy problems.

First, the gas valve holds the gas until the boiler sends a signal for the gas valve to operate. Gas valves have a tendency to make a chattering or humming noise when faulty and sometimes accompanied by a strange hooting or chugging noise. The chattering is the faulty gas valve opening and closing rapidly, leading to an inconsistent supply of gas to the burner (hence the chugging noise). Gas valve issues will require a Gas Safe Qualified Engineer to repair the fault.

Modern boilers have a fan connected to the gas valve which pulls the gas through. The fan speed provides the correct mixture of gas and air to burn efficiently and smoothly, before sending it into the combustion chamber. If the fan is sticking or seizing up it can produce cycling of the gas firing up and going out. This will only last a few moments until the boiler senses the gas hasn’t stabilised and will shut the boiler down. It will also issue a fault code. Again, this will require a qualified engineer to repair.

Burning the gas

Once lit, the gas burns in the combustion chamber to heat the heat exchanger. If the burner has a restriction to it or damaged or worn, then this could produce an unfamiliar noise or sound unusually loud in operation. Once the gas has burned, the products of combustion exit via the flue, and condensation from the burning process exits via a sump through a condensate pipe. Condensates can block, especially with freezing temperatures, which can lead to a sloshing noise from the boiler. This is the sump overflowing back into the boiler. You can check the condensate termination and make sure it isn’t frozen or blocked with leaves etc. Flues can cause hooting noises when they wear out. The engineer will check the continuity of the flue in this circumstance.

The best advice is to seek a qualified Gas Safe engineer to check it over. If you have any questions please get in touch.

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