Hot Water/Combi Boiler Problem! (Merged)

dirtyred619 · 28 September 2005 at 4:40PM

Hi

I have a combi boiler in my house and all has been fine until recently. The central heating is working fine but the hot water is no longer runs hot. Has anyone got any ideas what this could be, any advice would be ace!

Cheers

economiser · 28 September 2005 at 5:22PM

It sounds like the diverter valve. This is quite a common problem with combis. When you turn on the hot tap the boiler has to divert the incoming cold water through the heat exchanger in place of the heating system water and the valve that does this sometimes gets stuck.

mitchb · 28 September 2005 at 6:02PM

My combi boiler has the same problem at the moment, an engineer was out looking at it today and initally thought it was the diverter valve but it turned out to be the diaphram that needs replaced.

robowen · 28 September 2005 at 7:19PM

mitchb wrote:

My combi boiler has the same problem at the moment, an engineer was out looking at it today and initally thought it was the diverter valve but it turned out to be the diaphram that needs replaced.

The diaphram is housed inside the divertor valve. This is easily replaced in most combis. Should cost about £15-£35 for a new diaphram kit.

rob

dirtyred619 · 28 September 2005 at 11:52PM

cheers all, lets hope its just the diaphram then and not the valve!

wolfpeltz · 5 October 2005 at 12:30AM

I have the reverse problem. Hot water operates fine, but the CH fires up for 10 secs then shuts down. The primary circuit gets hot, but the flow pipe warms up very slowly for only a few feet.

Pump working OK. Diverter and control 'seem' to be working OK. When removed I could operate easily manually. Diaphragm seems to work as it activates the microswitch, but is this meaningful ? (Biasi M90F.32S). The water just will not circulate.

I even altered the pipework, thinking it could be an air lock, adding bleeder points.

wolfpeltz

robowen · 5 October 2005 at 9:20PM

Is one of your valves on the flow or return closed off ??

I went to one job where this woman tried to top up her boiler and didnt know how to do it. She eventually found the right top up valve, but had closed off an isolation valve on the flow pipe.

This caused the boiler to fire up and then shut down 10 secs later.

wolfpeltz · 5 October 2005 at 11:25PM

No. Checked that one. Also no blockage in radiator circuit a I flushed it out after I had drained it.

mogman · 6 October 2005 at 10:46AM

I have a Ideal Combi Boiler with a megaflo water tank.
After every shower the tank keeps discharging water from the overflow, which is just in the airing cupboard hence we have water all over

Any help appreciated.

Mogman

catchdarren · 6 October 2005 at 11:15AM

It's that time of year....

Apologies for asking yet another question about CH....

We are about to move into a house with a very old (>20 years) back boiler CH system. We want to change over to a combi. Someone has suggested that we should get all the rads and pipework replaced at the same time. Does this make sense to those in the know...?

Thanks

D