Combi boiler - no hot water, central heating ok.

[mktb]

I've an Icon T combi boiler - no other markings or part numbers. From reading around it may be a Herman re-badge. Has a SIT 0.537.301 electrical box on it and what looks to be a CEME Eng pressure switch, partial p/n 5412/VAP-DR (?). Unable to get DHW from the system unless the CH is running, in which case hot water is usually available. Has been suggested the pressure switch is u/s. Any way to test this? Further info - have continuity between terminals at 12 and 3 o'clock, nothing between 9 o'clock and 12 or 3 (no terminal at 6 o'clock), with hot water tap running and not. Boiler switched off for this test.

Any info appreciated.

 

[Agile]

I think this has a fairly usual design of diverter valve.

It would seem that this has failed and is not indicating a demand for hot water.

Tony

 

[mktb]

Thanks for this, Tony - how do I identify this valve and any tests I can do to verify problem? Why do you suspect this valve (not doubting you, just trying to understand the system!) Thanks again.

Mike.

 

[mktb]

Sorry, further info. Think I might have found the diverter valve, or at least, something that has a bearing on things. This valve has a plunger that comes out of the top (well, side as it's mounted) which should act on a microswitch. Presumably, as the hot tap is turned on, the plunger should move and make the microswitch. It doesn't. With hot tap running, no CH, if I manually make the MS, the boiler fires up and presumably hot water.

Does this help confirm your diverter valve diagnosis? Any further checks, repairs or is it a replacement job?

Continued thanks.

Mike.

 

[Agile]

Thats it and you have confirmed its failed as I had diagnosed!

In many cases just the diaphragm itself can be changed but sometimes its better to change the whole valve particularly commercially when we give a years guarantee.

Tony

 

[mktb]

Thanks again Tony. Any idea where I can source parts - do you supply? If so how can I identify which diverter I have for replacement diaphram or assy? Any idea on prices?

Thanks

Mike