I live on the 4th floor at a 9-story building (60+ units in total). For the last few months I have been hearing an annoying humming / whining noise. After some inspection I realized that the source of the noise is the boiler room located at ground floor. I was able to measure the frequency of the tone and it seems to be exactly 440 Hz.
Technicians and a plumber suggested to replace the circulator pump, however, the board of trustees does not approve the expense (it's closely to $2,000 dollars including the pump and labor). They don't seem to approve the expense mainly because other residents don't seem to be bothered. Another reason is that it is not guaranteed if replacing the pump will actually solve the noise problem.
What do you think? Is the source of the problem really the pump? Or could it be that the pump is not receiving a proper voltage?
I will be glad to have your thoughts. I tried almost any possible isolation material (such as using rubber foam, door draft stoppers, acoustic panels).
The DB levels are pretty low. Despite that, the sound is being magnified through the hallway to the upper floors.
Here are videos demonstrating that: