Ok, all was ok before. Relatively new combi boiler and shower only fitted 3months ago.

Just had all new radiators fitted today along with a room stat.

mrshora was upstairs having a shower (thermostatic mixer shower fed off the combi) when I could audibly hear a droning sound coming from the boiler itself. NOT the shower.

Turned just the hotwater on. No sound.

Turn just the coldwater on. No sound.

Both on with the mixer and a drone comes from what sounds like within the boiler. It gets louder but stays a sort of ‘Whale calling drone’ – if that makes sense?

Help?!

You’ve got a whale trapped in your boiler. Do you know any Japanese people ?

HTH

http://www.talk.electricianforum.co.uk/archive/index.php/t-11306.html

Mixer valve. Looks like you arent alone.

I saw that thread and the noise is coming from the mixer shower though and not the boiler?

The Boiler in our house is one floor down and the noise is definitely coming through the boiler.

On the phone the Plumber reckons it could be pipes resonating down and through the boiler or there is a water pressure issue. Why didn’t it do this before then?

If it’s resonance then it could be triggered by a specific demand pattern on the boiler, same as when you blow over a milk bottle at the right speed to make it sing. Too little or too much and you don’t get the noise. Could also be partly due to some trapped air in the system after the new rads went in.

We have something with a cooker, sometimes when the grill is on, you get a drone. Sort of medium pitch though.

With ours it’s supposedly the gas supply pipe having a kink in it that shouldn’t be there, causing some sort of resonance when loads of gas goes through.

Have you tried turning on all the hot taps in the house at once, see if that triggers anything.

Could also be partly due to some trapped air in the system after the new rads went in

Air in the system? Bleed the rads?

same as when you blow over a milk bottle at the right speed to make it sing

EXACTLY that sound.

Update, Boiler manufacturer helpline think its a deadleg in the pipework from when the radiators were fitted.

HOWEVER – I thought the radiators were on separate pipework/closed system and not on the same?!!

Why didn’t it do this before then?

because mains pressure fluctuates..

worth bleeding rads.. deadlegs are bad as air accuamlates in then if they have a high point and air in the system can do funny things to the water system in terms of movement etc

also do you get the noise when the heating is on + mixer action or just mixer action and heating off?

The Plumber is back today to replace the chemical/flush out and replace with the inhibitor.

also do you get the noise when the heating is on + mixer action or just mixer action and heating off

I’d need to double-check that but from memory both heating/water were on at the sametime as the mixer to get the noise.

The manufacturer said when the radiator was replaced in the bathroom they could have created a deadleg there. Thing is- they are both on seperate loops (i.e. hot water = open, central heating water = closed. So why should it matter?

Anyway I’ll speak to him.