Where’s this intermittent buzzing coming from. Driving me crazy!

[DavidAUK]

Aaargh! There’s a buzzing sound coming from somewhere in my plumbing and I can’t identify it. It happens for between 5 seconds and 30 seconds and is noticeable most in our en suite.

I have three Grundfos pumps for upstairs heating, downstairs heating and underfloor heating. I also have a Grundfos pump with autoadapt which I bought more recently to give me hot water more quickly.

I’d guess that it’s this last pump that’s causing the buzzing because that’s what a plumber told me. I’d like to know for sure though.

i pointed a security camera at it and noticed that autoadapt led goes from solid to blinking when I push the button, which I don’t think is right. The camera picks up the buzzing noise but there’s no corresponding visual clue. It’s in the roof next to the water tank.

Anyone had this before?

I have a video of the buzzing but it’s not great. It starts suddenly and stops suddenly, which seems like the action of a pump. Could be something else though.

 

[BlueLoo]

Do you live in a hotel?

4 pumps?

 

[DavidAUK]

Ha! The house used to be two flats. It’s how the house came, aside from the instant hot water pump which I got installed a couple of years ago.

 

[BlueLoo]

If the pump was the last thing to change before the buzzing, it's likely that doing it.

Try running it in CS mode (constant speed).

Auto pumps are a ****ing pest.
Great idea but not something you can just switch out an old CS pump with.

 

[DavidAUK]

I've been on constant speed for a while and the intermittent buzzing is still happening, so maybe it's got nothing to do with the Grundfos. Is there something else that would cause the noise?

Here’s a lousy video of me trying to catch it before it stops. It’s louder than the video suggests.

 

[Deleted member 267285]

Does it do it after anything, eg running hot water, flushing a toilet? Any dripping taps?

 

[DavidAUK]

Pretty sure it's when something's drawing water. Usually happens when someone flushes a toilet but can't be 100% sure.

 

[Deleted member 267285]

Pretty sure it's when something's drawing water. Usually happens when someone flushes a toilet but can't be 100% sure.

So check the cold water storage cistern(s).

 

[gas112]

do you have a pump to get rid of boiler condense this would run in short spells

 

[BlueLoo]

I've been on constant speed for a while and the intermittent buzzing is still happening, so maybe it's got nothing to do with the Grundfos. Is there something else that would cause the noise?

Here’s a lousy video of me trying to catch it before it stops. It’s louder than the video suggests.

Put the pump back as it was then

 

[BlueLoo]

I've been on constant speed for a while and the intermittent buzzing is still happening, so maybe it's got nothing to do with the Grundfos. Is there something else that would cause the noise?

Here’s a lousy video of me trying to catch it before it stops. It’s louder than the video suggests.

That not the shower pump going is it?

 

[DavidAUK]

Thanks everyone for jumping in. If it isn't clear already, my knowledge of plumbing is pretty poor.

Following some comments above I did some tests and the buzzing is indeed caused by a toilet being flushed.

In the roof is a system boiler, a hot water tank, two expansion tanks, a grundfos pump and a second grundfos pump to give instant hot water. No cistern, as far as I can see. Under the stairs is another grundfos pump. Not four pumps as I said earlier in the thread.

I've noticed that the grundfos under the stairs has no lit LEDs. Does that mean it's dead?

 

[Notch7]

Has the wife got a new toy