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...
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.
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...
I recently had central heating installed. A Megaflo tank and a Vaillant Ecoplus 630 boiler. The house is warm and I have hot water, so there is no emergency. I have nagging feeling it's not working 100%.
1. The pressure seems low. It's at 1.7 bar. I had to bleed the towel rail (for the second...
I stayed in a nice hotel yesterday (Soho Hotel). The Attack the Block movie after-party seemed to be happening there. I wasn't invited. Anyway, I digress...
I liked the fixtures and fittings. The electric sockets etc seemed to be Wandsworth. Loo was Duravit. Flush was perhaps Grohe? Wasn't...