The cold weather is here and yet again I have the same problem: humming radiators.

I have done a lot of web searching and forum reading and not found any solution.

The system is an oil burning furnace which heats a two-story house with a single zone by hot water. There is a circulator pump. Sometimes when the system is running a medium-pitched hum occurs which seems to be coming from several of the upstairs radiators, but it is hard to tell because it is a very ethereal hum.

It has nothing to do with air in the radiators. I have bled them and it makes no difference.

One thing is that the hum is much more noticeable since some work was done on the radiator a couple of years ago. I think all they did was replace the oil pump (not the circulator).

How can I figure what is causing the hum and fix it.

  • Sounds likely to be vibration from the circulator, or from the boiler, being coupled through the pipes. Changing how the pipes are mounted to the basement ceiling might transfer that vibration somewhere else. (In my case, it comes up through the floor into my living room; I need to try Something Else at some point.)
    – keshlam
    Commented Nov 2, 2014 at 19:16

1 Answer 1


Sometimes the circulating pump moves too much water and causes noise and vibration. Years ago when I was doing residential service and most pumps were single speed I carried cut down impellers just to fix this problem. Most pumps back then were from Bell and Gossett. Today there are numerous fixes. take the name brand of the pump, the model number and serial number of the pump, (a picture may also be a good idea) to a local hvac shop that services hot water systems. They can look up the flow from a chart and recommend what to do: a cut down impeller, smaller pump, a multispeed pump etc. This should fix the hum or vibration.

  • That is pretty interesting information. I will check into this. Commented Dec 18, 2016 at 16:02

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