No hot water except when rads are on.

[Trigger]

Unless we have the central heating switched on, we cannot get any hot water on our Ravenheat RSF 820/20T. What do you reckon is the fault? If it is the microswitch on the diverter value, is it easy to replace?

Bobby

[Nigel Heather]

I suspect it's the three way valve that swiches between hot water, heating, both or none.

This will probably be near your hot water tank and is pretty obvious because it will have three water pipes and an electric cable running to it.

9 times out of 10 it will just be the motor drive that has failed which can be replaced without interrupting the plumbing at all. If the valve has failed then you will have to do a full or partial system drain.

Guess at prices - just the motor - £30 to £40, complete valve and motor £80 - £120

It could be the programmer but I doubt it.

The valves can often be set manually - but obviously that either fully on or off - no automatic switching - but at least you should be able to set it to hot water and no heating for example.

Cheers,

Nigel

[ronny]

"Nigel Heather the-heathers.co.uk>" I suspect it's the three way valve that swiches between hot water, heating,

The boiler of the OP is a combi, probably the diaphragm inside the diverter valve, might be easier to change the full valve than repair

[Trigger]

Thanks Nigel and ronny.

[DCA]

Nigel Heather I suspect it's the three way valve that swiches between hot water, heating,

Nigel Top posting is not very helpful. Outlook seems to be the only reader where users cannot change default response position. Even if his boiler had been a standard type, your response is incorrect.

3 way valves almost without exception sit in the 'both open' position when un-powered or faulty. David

[Andy Champ]

This can be fixed with the add-in "quotefix". Google will find it.

Andy

[Kevin]

or just use Thunderbird

[Heliotrope Smith]

Is the exception the Honeywell 3 port mid position valve that rests unpowered with heating (port a) closed and hot water (port b) open, (which seems to be one of the most common 3 port in use) or are there others?