No hot water but heating works on combi boiler.

[Coops025]

Hi guys,

Recently my hot water has stopped working, the boiler fails to flare up when i turn it on however on the rare occasion it will provide hot water for a short period and the boiler does flare up.

If i turn the heating on the water is hot as long as the heating remains on.

What could be causing this?

I had the heat exchanger replaced last year because it was leaking if that helps.


thanks.

 

[45yearsagasman]

What would really help is you telling us the make and model of your boiler.
Don't take it to heart, I wish I had a fiver for every time this question was asked.

 

[Coops025]

Hi Sorry,

It's a Sime Super 90Mk2

 

[45yearsagasman]

More than likely the diaphragm in the diverting valve has stretched or split.
The diaphragm is available as a spare, but its not the easiest one to change.
The gas valve is best removed to make access easier and therefore its RGI work. About 1.5 hours work all going well for a pro.

 

[Agile]

I think this is the same diverter valve as the Alpha CB28.

Because the shaft seals often start leaking so commercially I would always change the whole valve.

If I am correct about the valve then the diaphragm assembly has different shaft lengths from the common Giomini units.

However, the actual diaphragm itself IS the same and just needs the old shaft to be reused. This means removing and refitting a very small circlip which can shoot all over the room and get lost and is therefore best pre-prepared before visiting the customer.

Tony