I have an AlphaCB24/28 wall mounted boiler, approx. 8 years old. Whilst running my central heating and/or hot water, the boiler would cut out and a continuous red light would replace the flashing orange light! After resetting the boiler using the reset switch the boiler would function O.K. for between 15 minutes and two hours, when it would cut out again! I called in a local reputable plumber/heating engineer and he replaced the overheat stat. and repressurised the expansion tank and cleaned the flue venturi. However, the same problem still persists. The engineer suggested that it could actually be an electrical problem, so I am now plucking at straws for a solution. Info., the incoming water pressure is within the green band on the pressure gauge. Help!

Combi-boiler-turn hot water tap on/off and the heating stops for ...

singletrackworld.com/.../combi-boiler-turn-hot-water-tap-onoff-and-the-...

Combi-boiler-turn hot water tap on/off and the heating stops for 20secs ... hot watertakes priority over central heating so when you run the hot tap, heating is ... Yeah onmy worcester combi there is a diverter valve - it feeds either the heating or ...

My central heating works but I have no hot water - 24'7 ...

https://www.247homerescue.co.uk/my-central-heating-works-but-i-have-...

Diverter valves switch heat between the hot water and the central heating. When youturn your hot tap on, the diverter valve temporarily shuts off the water supply ...

Does your boiler keep switching itself off? Here's why ...

www.dhs-uk.com/does-your-boiler-keep-switching-itself-off-heres-why/

Jul 7, 2015 - ... Bathroom Suites, - Showers, - Wet Rooms, - Taps and Accessories, Information and ... Low water pressure can cause your boiler to turn itself off. ... boiler is not turning off, you aren't getting the amount of hot water you require. ... If there is air in your central heating system, then your boiler may shut down.

If the thermostat wire run passes anywhere through, beside or inside any metal surfaces and the wires touch any of the metal its the same as if you turn the stat to on. I've seen this a few times. Easiet way to detect it, if its inside the house is at night in the dark. Look around when its doing this you may see the small spark when it goes on. Otherwise you will need to inspect the entire run from the stat to the untis, etc.

check pump is running ok..if not replace it the pump, if pump is ok then u will need to descale boiler put in system by rad or if not combi then put in open vent tank make shure its the small tank also make shure the valve in tank is not stuck

Symptoms sound like crossover might be part of problem:
Crossover is when cold water enters hot water line due to faulty plumbing part like check valve, mixing valve, or bad faucet cartridge.
http://waterheatertimer.org/Crossover.html

overheat stat

Is your boiler heating your domestic hot water if so i would turn water off to water maker and see if your boiler pressure stays down below 20 psi. If so water maker is bad. The other thing that could cause this problem would be the boiler pump is out.

hi sounds as though the system is sludged up & needs power flushing.the reason is that the water cannot circulate so over heats & pumps into the header tank.
expect to pay approx 350 400 pounds to have it properly cleansed, it will restore the system efficiency.
The other area worth considering is that it could be a faulty pump os that when th eboiler fires it cannot circulate so in turn expands & vents into the tank.

My advise is to arrange for a corgi engineer to sort it out for you.

Kindly

Richie

what about flame rectification probe (flame proving probe)

the boiler should modulate to controll the radiator temperature but the central heating will go off whilst you are drawing hot water

baxi boiler relief valve blows off when heat is turned on when hot water is working it is fine