Why Is My Boiler Humming?

If your central heating is making a humming noise, the main culprit is usually your central heating system. The humming noise can also be accompanied with a vibration which again leads to a pump issue. Although the main culprit it is not the only cause of a humming noise

Below, we’ve listed four common problems that can cause a loud humming noise to come from your boiler.

Heating Elements

A humming boiler could mean that your heating elements are not working at their best which includes the following:
  • thermostat
  • central heating pump
  • pressure gauge
  • filling loop

Loose components

The most common cause of a boiler humming is a slight vibration in the casing. If your boiler has recently been serviced or repaired and the humming noise started shortly after then loose components is the most likely cause.

Components to look for are as follows:

Loose brackets
Solution (try tightening the screws with a screwdriver)

Vibration of the unit itself
Solution (get a professional to secure the unit with brackets)

Circulating Pump Set To Wrong Speed

Every central heating system is different to the next, one home may have 10 radiators while another may have 14. One home may have a one layout meanwhile another home has a layout with more piping. Different homes for these reasons and more require a bespoke speed for that particular home.

Luckily boiler manufacturers integrate a variable speed dial which allows you to easily increase and decrease the speed of water circulating your home. Simply located your circulating pump and adjust the setting to the lowest setting to see if the humming stops.

High pressure in the system

Boiler pressure is the balance of water and air within your heating system. In order for your boiler to pump hot water around the pipes in your home the pressure needs to be the correct amount.

High boiler pressure puts unnecessary strain on your heating system and the boiler could break down.

How To Check My Boiler Pressure

On average your boiler pressure should be between 1 and 2 bar however some boilers are different so checking your boiler manual.

To check your boiler pressure, you need to locate the pressure gauge on your boiler. If there is the correct amount of pressure in your system, the needle should be between 1 and 2 bar.

boiler pressure gauge

Most boilers have a pressure gauge similar to the image shown where green is between 1 and 2, this shows the zone of ideal pressure. The red zone which is greater than 2 is then indicated in red highlighting the critical strain on your boiler.

How To Lower Boiler Pressure

If the boiler pressure is above 2 bar or the needle is in the red zone on the pressure gauge then you will need to release some of the pressure bringing it back down to a correct amount. Step one is to turn your water and heating off which should bring the pressure back down.

If the problem continues to occur then to release some of the pressure the easiest method is to bleed a couple of radiators in your home. Simply turn off your heating and with a radiator key or a flathead screwdriver turn the valve and with a towel or bowl catch the water, once the pressure has lowered below the red zone then close the valve.

There are many different noises that your boiler can make, and while some of them can seem worrying at first, most can easily be fixed. If you are unsure about any noise your heating system is making, the safest thing to do is call a professional.

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