potterton puma 100 combi CH problem please advise

[hyperint]

I have a potterton puma 100 combi. The hot water is fine, the problem is the radiators will not heat up.

When the central heating switch is on the boiler fires up and then it shuts down shortly afterwards. The pressure needle is up near 3. I tried bleeding the radiators and recharging it, to get the pressure needle down to between 1 and 2, the problem is the pressure needle rises back up above 2 afterwards. I'd really appreciate any Ideas on what the problem in and what it would cost to fix?

 

[kevplumb]

diverter valve?

 

[hyperint]

Thanks Kev, called a plumber out and he confirmed it was the diverter valve, any idea how much one of those costs?

 

[ChrisR]

First check if you have any hot taps dripping. This will stop the heating working.

There are two parts to a diverter, there's awax capsule at the front which is a doddle to change. Or there's the whole thing, which can be difficult if access is poor from underneath. Takes a lot longer but still within an hour.

Retail price for the whole thing is about £115, the wax capsule say £25-30.
Or you can buy the whole thing from a shady geezer like me for £35
Even shadier geezers will tell you you can't buy the wax capsule by itself.

See http://www.partscenter.co.uk item 453085 for the whole thing. They do not sell the capsule alone.