Circulator pump leak at mounting flange (C) Daniel Friedman Circulating Pump Noise Repair

  • CIRCULATOR NOISES - CONTENTS: how to diagnose & fix noisy heating zone circulator pumps & controls. Humming, buzzing, burbling, vibrating hot water heating circulator noise diagnosis & repair procedures.
  • POST a QUESTION or READ FAQs about how to repair circulator pump noise
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Heating zone circulator pump repair procedures for noises:

This article describes how to diagnose & fix noisy circulator pumps on hot water or hydronic heating systems.

We distinguish among buzzing relays that control the circulator, vibrating electric motors, shrieking circulator bearings, and circulator pump noises. Understanding the noise made by a heating zone circulator pump and whether or not the noise is normal can help us diagnose and fix equipment without wasting a lot of time chasing the wrong problem.

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Circulator Pump Noise Repair Guide

Reader Questions: Heating Zone Circulator Pump Noises, heating system noises, or noises when heat is turned off

Humming at the boiler

(Oct 13, 2012) zena123 said:

Help, please ! Central heating system is turned off. However, an unpleasant hum comes from central htg. boiler. When elec. is turned off at consumer unit, humming ceases. Any ideas gratefully received. Tx.

Bang noises at the boiler or expansion tank

(Oct 29, 2012) Jim said:

When circulator pump turns off, there are 4 pairs of bang-bang, which seem loudest at expansion tank. Draining expansion did not change. Heating and other operation is OK. I suspect, and will replace, the coupler between electric motor and impeller.

Trickling water sounds in the heating system

(Jan 10, 2013) Anonymous said:

I hear trickling water on one of my baseboard on my top floor everytime the heat starts to work. It goes away after awhile. I bleed that baseboard and it still trickles.

Squeeking Noise at the heating boiler

(Mar 13, 2014) Steveo said:

I have a squeeking noise that only happens early in the day and then again at is coming from the water-out pipes (hot) and the sound "goes away"...I'm really confused. The pump's coupling was changed this season and it was oiled...any ideas??



Your heating service technician will probably check for a humming relay, control, electric motor, or burner motor. I'd turn off the system while waiting, in case it's an electric motor that is jammed or stuck.


I'm not sure what's going on but I'd start with the most dangerous: checking that the BANG! is not coming from the oil burner itself.

See PUFFBACKS, OIL BURNER to rule out that hazard.

Anon: trickling water means there's probably air in the hot water heating system piping. See our air-bound heating system diagnosis and repair articles in the links below.


I'd try to track the noise to location as well as by whether or not equipment is running or not. It could be an expansion/contraction of piping moving through a tight opening as temperatures change.

Louder sqeaks and shrieks are often a failed or failing motor or pump bearing.


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