motor / humming / resonating noise from flat plumbing

[jayjon]

Hi, any answers to this question are greatly appreciated.

My friend lives in a house that has been converted into flats.

When the top floor resident is at home a loud humming or "engine" noise resonates through the whole building's plumbing system. This does not happen when the top floor resident is out. The noise doesn't happen all the time, but when it happens it goes on for about 30 seconds to a minute.

Nothing the other residents do will make this noise happen - they have tried!

The top floor flat is built into the roof if that is any help. As for what action they are doing that causes this noise - I'm afraid no one knows. This resident won't cooperate.

It *sounds* like this is happening when the person uses a certain tap. Is this feasible please? It doesn't go on long enough for it to be a washing machine or dishwasher, and it probably happens too often for it to be a toilet flush.

Again, any help appreciated.

Jay

EDIT: Just thinking about this, is there any device (such as a waste disposal unit) that could be causing this noise? It's a very "even" noise.

 

[bathjobby]

Sounds like a toilet machinator which would be fitted into a loft conversion i.e. a waste disposal unit (electric motor grinder) fitted to the loo which grinds the output when toilet is flushed, to allow it to be put down a 2"'ish waste pipe.
But you say its too frequent for that ! Maybe its a combination of that And a waste disposal unit on the sink.
You are going to need their cooperation in using their appliances whilst you listen out for the noise....

 

[Agile]

Often a macerator is used on both the toilet and bathroom and/or kitchen.

Tony

 

[jayjon]

bathjobby, Agile, thanks very much. By the sound and the duration this sounds like it could be the problem.

Cheers,

Jay.

 

[ChrisR]

It doesn't need a macerator to sound like a motoboat on the roof. It's very likely to be just a rubber washer resonating in the loo cistern. The plastic float valves can sometimes be adjusted to stop it, but changing the washer usually works. If not, see if there's a brass version of the valve - may not be one available.

It'll do it all the time the cistern is refilling, up until the final drip - easily half an hour.

Macerators on loos only run for a short period, so unless he's in the shower for half an our or there's a pump on a washing machine or similar, that doesn't seem to fit.

 

[jeff the gasman]

Most likely a part 2 ball valve diaphragm washer resonating. IMO