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Why Is My Boiler Making a Loud Humming Noise?

If your boiler is making a loud humming noise when it operates, you’ll want to check for:
  • Loose components
  • A circulating pump that’s set too fast
  • High pressure in the system
Now, to be clear, these aren’t the only issues that can cause a boiler to hum but these are the most common issues and the easiest for homeowners to check on their own.

Not quite sure where to start investigating? Don’t worry, we’ll take a closer look at these 3 issues and show you what you can do to stop the humming.

Don’t have time to search for the issue yourself? Just contact us, we’ll find the source of the problem and fix it in no time.


Check for loose components

The most common cause of a boiler humming is a slight vibration in the casework somewhere. This is most likely the case if the humming noise started after a professional performed maintenance or repair work on the boiler.

What to do: Wait until the humming noise starts then head towards the boiler (usually located in the basement or a storage area). 

If the humming noise gets louder the closer you get to the boiler, start looking for:
  • Loose brackets. If this is the issue, try tightening the screws with a screwdriver.
  • Open panel/compartments. If this is the issue, make sure all compartments are securely closed.
  • Vibration of the unit itself. If the unit itself seems to be vibrating, you may need to have a professional secure the unit with brackets to stop the vibrating/humming noise.


Check your circulating pump

Your boiler circulating pump is what moves the heated water from the boiler into your home’s radiators and back to the boiler again. The speed at which that pump moves the water is usually determined by the professional who installed the system. 

But sometimes, if the circulating pump is set too fast for your home’s setup, it will cause vibrations within the system that sound like a loud humming noise.

What to do: Locate your circulating pump. These can usually be found connected to a pipe near your boiler and should have the speed settings displayed on the face of the pump. Here’s an example of what a circulating pump looks like.

Once you’ve located the pump, reduce the speed. Typically, circulating pumps have an adjustable dial on the front. If the pump isn’t already set to the lowest speed, push the dial all the way to the left and wait to see if the humming noise stops.

If the humming stops and you want to keep the pump set at a lower speed, just check that the radiators heat up properly and the boiler isn’t cycling too fast. If you can’t find your pump or aren’t sure how to adjust the speed, have a professional do this for you

Note: some older pump systems operate at one speed only. If your pump only has one speed, you’ll need a professional to determine whether the speed of the pump is really the issue at hand.


Check your boiler pressure

Your boiler should keep a constant pressure as its operating. A healthy boiler will never exceed 12 to 15 psi (pounds per square inch). If your boiler is over 15 psi, the higher-than-normal pressure can cause a humming/buzzing noise.

What to do: Locate the pressure gauge on your boiler. These are usually located on the side of the boiler or on the front panel. Here’s an example of where you might see your pressure gauge on the boiler.

Read the gauge to make sure the pressure is lower than 15 psi. If it’s higher than this, have a professional determine the cause of high pressure and fix it.


Boiler still humming? Ask a New Jersey tech

If you’re still unsure what’s causing your boiler to hum, just contact us.

We can inspect your boiler system, pinpoint the noisy culprit and fix the problem.


Related reading:

  • Why Is My Gas Boiler Not Heating My Water?
  • Should I Convert From Electric to Gas Heating?

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