Vokera Compact 29 exchange heater noise

[gurth]

Gents

18 month old Vokera Compact 29 combi boiler installed with new radiators, pipes, the lot (renovation project).

Recently inside the last 2 months the boiler has started to 'whine' when running the hot water (YouTube: https://www.youtube.com/watch?v=qaN4Rrvy2BM).

Rarely does the whine occur with just the central heating although it does on some occasions but only for a short while and only very quietly.

I've taken the cover off and the pump is turning fine with no play, the fan is working again with no play.

If I cover and restrict the silencer the whine continues which in my mind rules out the fan as I would expect it the noise to stop as the fan is turning / pulling less and less.

Sound seems to be coming from within the exchange heater, if I place a screwdriver on the case and put my ear to the driver I can convince myself its strong in one particular corner than the others - although it's loud it seems to be coming from everywhere.

Answers on a postcard please.

 

[ianmcd]

The silencer as you call it is the air intake stop blocking it you will damage the boiler, it is a combustion related fault you need an RGI to sort it for you Im afraid

 

[gurth]

Silencer is what Vokera call it looking at their documentation but yes it's an air intake. Engineer is stumped as me.

 

[ianmcd]

It sounds as though your combustion settings are out you need an RGI with a flue gas analyser to check these, it may be that the inlet gas pipe is too small is it 15mm and if so how far from the boiler does it run in 15mm before it goes up to 22mm ?

 

[easyas123Viessmann]

It is called a silencer as it prevents an acoustic vibration from occurring when drawing in air. your heat exchanger could be obstructed. Is the boiler cycling? can you measure the temperature of the flow and return?

 

[gurth]

Analyser was done yesterday, passed with flying colours (yearly check-up and why I originally had the engineer booked).

The noise seems to be coming from the 'main heat exchanger' but the issue is when the hot water is running - I'd expect the noise to therefore come from the 'domestic hot water heat exchanger' but that's elsewhere.

Inlet into the house is 15mm (Victorian 1898 mid-terrace) and comes under the stairs before going upto 22mm and running upstairs around the landing and down into the kitchen. I'd say 14 metres from the gas bx on the side of the house to the boiler.

Many thanks.

 

[gurth]

doesn't appear to be cycling, all in tune with the thermometer. If I turn it down for the day the boiler stays off for the day bar the odd stir (I think I read it stirs every 20 mins).

I can't easily measure the temp of the flow and return sorry, both seems warm.

The issue is only when the hot water tap is turned on, the noise starts then until I close the tap again.

Is this kettling in my 'domestic hot water heat exchanger'?

 

[easyas123Viessmann]

Not very likely. is your hot water running hot and cold?

 

[gurth]

no, hot water is constantly hot.

Just been reading around and trying to pinpoint the noise.

If I flush the toilet the noise stops briefly, made me think it was pressure related but no amount of fine tuning the flow seems to make a difference - bar restricting the flow to a trickle.

Was working fine until recently, I did have a 'smart' water meter fitted not long ago. Could it be that?

 

[easyas123Viessmann]

Could be some kind of water hammer. Strange that its in the boiler though. Try fitting a hammer arrestor in the hot water pipe near to the boiler. they arnt to dear and easy to fit.