Combi boiler will not give hot water on "hot water only

[Ballysillancfc]

As of yesterday, I can only get hot water from the boiler when the full heating is on.....not good news in June!

Anyone know of a likely explanation why i'm not getting hot water on the "hot water only setting"? Boiler water pressure seems to be fine.

 

[plumbtraders]

I also got the same problem. can any one help me out please

Thanks

Rahul

 

[bengasman]

If your combi is a white one, it could be the diverter

 

[plumbtraders]

What do you ment by white boilers. Can you explain something about white

 

[namsag]

Its called sarcasim. Thousands of boilers out there it helps with advice if you give make and model

 

[Agile]

Apart from the Netaheat and the Ideal Sprint most boilers are white!

So the advice is still good but also would apply to a brown Ideal Sprint as well.

Tony

 

[Ballysillancfc]

If your combi is a white one, it could be the diverter

Assuming there is a problem with the diverter, is that a big job to fix/replace?

 

[glasgowgas]

ballysillan

post your boiler make and model

post the faults in a bit of detail

plumbtraders

don`t hijack post

start your own thread again giving boiler make and model and list its faults

 

[Agile]

I always say that brain surgery is easy for a brain surgeon but it would be difficult for me!

Similarly its usually an easy job for me to repair a diverter valve and we would usually charge £106 in our local area.

There are some white box boilers like the Worcester CDI which is tedious for a professional and I advise that Worcester repair it at their fixed price repair.

Other white box boilers are better repaired by replacing the whole diverter valve like some of the Vaillants.

Tony

 

[Ballysillancfc]

ballysillan

post your boiler make and model

post the faults in a bit of detail

plumbtraders

don`t hijack post

start your own thread again giving boiler make and model and list its faults

It's a Grant Combi 90 GG....not much obvious to say apart from the fact it's not providing any hot water on the Hot Water only setting but will if the full heating is on. Pressure vessel was replaced within last six months.

 

[OilLecky]

Switch the electrical power off. Locate the Diverter Valve inside the casing and remove the cover from the black plastic box on the end. Inside you will see two micro-switches. Get an assistant to open a hot water tap while you watch the small steel pin. It should push outwards and operate the micro-switches. If not it is most likely the diaphragm inside the Diverter valve has a hole in it. Please check this and report back.

 

[Ballysillancfc]

Switch the electrical power off. Locate the Diverter Valve inside the casing and remove the cover from the black plastic box on the end. Inside you will see two micro-switches. Get an assistant to open a hot water tap while you watch the small steel pin. It should push outwards and operate the micro-switches. If not it is most likely the diaphragm inside the Diverter valve has a hole in it. Please check this and report back.

The small pin has a black plastic cap on the end of it which pushes the switches right? This fell off when i was taking off the cover but i worked out where it came from.

The pin is moving but not enough to put pressure on the two switches - does this sound like a diapphragm fault?

 

[OilLecky]

OK Bally. One more thing to try. Find the Thermostatic Mixing valve. It has a grey plastic head with numbers written on it. With everything powered up, (mind your fingers!) get an assistant to open a hot tap, watch the pin on the diffuser valve and adjust the Termostatic Mixing valve. See if this moves the pin sufficiently to fire up the burner and if so job done.

If not we could have a couple of options. Are you are in a hard water area and do not have a water softener or Combi-mate? ( Ignore the electrical things clamped around the water pipe..they don't work.) If so maybe your "Heat-plate" heat exchanger is clogged, reducing the flow of water. If you are in a soft water area then this leaves your Diverter Valve diaphragm.

 

[Ballysillancfc]

Tried the thermostatic valve - it did seem to cause the pin to move more and it actually contacted the switches briefly but only for a few seconds. No joy in the end though.

The water here is slightly hard to moderately hard.....and there is no softening system installed.....is there any way to confirm that the heat exchanger is clogged? and how would you go about resolving that?

My instinct tells me that the diverter diagnosis is correct but if there's any easy way to check the heat exchanger i'll do that before i get the diverter replaced.

 

[Agile]

I expect its a failed diaphragm in teh diverter valve.

The plate HE is easy toi check by measuring the temperature differential across the primary connections. It should not be a lot more than about 15° C.

Tony