Sime Friendly hot water problem

15 Jan 2010
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United Kingdom
I have been having problems with my Sime Friendly boiler.
The hot water is warm at best and sometimes just cold. I've changed the diaphram in the diverter valve but it has made no difference. The old diaphram didn't seem damaged anyway when I took it out.

When I turn a hot tap on the burner fires up but it seems to heat the central heating rather than the water, even if central heating is turned off.

Grateful of any advice.
Many thanks

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Diverter valve is passing to the heating,,as we say. Basically means not all the heat energy generated by the main heat exchanger is being transfered to the seconary heat exchanger(hot water exchanger) and most of the energy is escaping to the hting circuit. Sometimes a full service kit on the diverter will cure other times a new diverter is req. May be xxxx on the seating of the diverter. Have had mixed fortunes servicing these Giannani valves with this problem.
Thanks for your reply. Would a new diverter valve sort this problem then?
When I took it apart to fit the new diaphram there was a lot of bits and dirt etc in it. I cleaned it as best I could and from the outside it seemed to be working. i.e. the little plunger pops up when you run the hot water and goes down when the heating only is on.

If fitting a new diverter valve will cure the problem I'll be happy with that rather than trying to service the old one.

First your boiler is not really friendly at all !

I would usually replace the whole valve because my few attempts to clean them have not resulted in complete or longterm solutions.

Part of the problem is these boilers were cheap to buy and the system was never properly cleaned so tere is a lot of dirt in them.

A friend of mine has one and I did spend a long time cleaning his as he does not like spending money. It was so unsuccessful that I replaced the whole valve after a few weeks. It was not so bad as his wife keeps me well supplied with coffee and drinks so its relaxing spending time over there.

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No your right it doesn't seem friendly at all!
Just want to get it sorted out now because I'm sick of having cold showers!
Looks like a new diverter valve then. I just wish I hadn't spent 27 quid on a service kit :(

Thanks for your help
You will get the DHW back close to normal if you close one of the CH isolating valves before taking a shower.

They often leak afterwards. If you did change them put in a full flow valve.

Ok thanks. So I need to close one of the isolating valves on flow or return pipes to give me hot water?

I'll do that over the weekend and change diverter valve next week.

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