Hot water / boiler issues

stevetuk

I have no hot water from my combi boiler unless the taps are opened full pressure/blast and then the water is literally boiling hot. Which is odd because normally that would be too much pressure for the boiler to continue to heat. If the taps are turned on any less than full, then the boiler won't fire.

I've had British Gas out twice: first time the engineer said nothing was wrong. The second time they changed the heat exchanger but that has not fixed the issue.

I've had a plumber out who has said I just need to get the right pressure, i.e. turn the taps on full blast. This does produce hot water but only unbearably hot water.

The issue is affecting all of the taps and my mixer shower. There was never an issue before (3 years same house, same boiler/taps etc).

Everyone seems to be saying there's no issue but there obviously is. Does anyone know whether it's likely to be the boiler, or the taps, or the water, and what the cause might be?

Thanks

Strider590

Is there not a temperature setting for DHW (domestic hot water)?

Alex1983

What boiler do you have?

stevetuk

The boiler is an Alpha CB24X

There is a thermostat on the boiler for the heating temperatures - I haven't changed it since I moved in to the property and had no issues before but it is set to full. I'll try turning that down but I'm still wasting heaps of water having to open the taps on full (and spraying it all over the show at the same time) just to get the boiler to fire

Alex1983

I'd suspect the diaphragm in the diverter valve, you can get a service kit to repair it but is abit awkward.

Easily proved for someone that knows, just manually make the flow switch when the taps running at a normal flow and see if the boiler runs normally.

stevetuk

Alex1983 wrote: »

I'd suspect the diaphragm in the diverter valve, you can get a service kit to repair it but is abit awkward.

Easily proved for someone that knows, just manually make the flow switch when the taps running at a normal flow and see if the boiler runs normally.

Thank you! Did a bit of reading, it does sound like it could be that from similar symptoms other people have experienced. I've called out British Gas a third time...if they can't sort it out this time around I'll cancel the plan and go to Homeserv or something...!

malky39

stevetuk wrote: »

Thank you! Did a bit of reading, it does sound like it could be that from similar symptoms other people have experienced. I've called out British Gas a third time...if they can't sort it out this time around I'll cancel the plan and go to Homeserv or something...!

I am surprised that british gas have had to be called out a third time for this, as mentioned it does sound like the diverter valve diaphragm
needs replacing. Which can be had for £6 on ebay and is a common part for a british gas engineer to carry.

MrBluesky_2

Usually its the Diaphragm operated diverter valve & flow switch but you have had bg there so they will have tested them and observed their operation and check the boiler and the system is set up correctly, i hope.
Just ask the next repair company to exchange the diverter valve,flow switch brassware and the electric micro switch.
Please try to reduce the hot temperature on the user panel,its still summer and your boiler does not have to work so hard to get hot water.
Your boiler repair is a simple job but the rest of the system has to be correct as well but your plumber would have checked what the boiler supplies,taps,showers etc.
Good luck,

stevetuk

I forgot to reply to this earlier but thanks everyone for the advice - turns out it was all absolutely spot on. The minute they replaced the diverter valve/flow switch it fixed the issue. I can't believe three call outs from British Gas didn't get that picked up. I actually told them I'd asked on here and that's what people said: the engineer just replaced those parts as instructed and it fixed it!

I've made a complaint to British Gas, someone should have diagnosed it earlier and it shouldn't rely on me asking strangers on a forum (who obviously know more!).

So thank you, I now have hot water on demand again