Worcester 24i combi boiler problems with rads getting hot

[begsy]

I am having a nightmare with my Worcester 24i combi boiler and my regular plumber cannot figure out what the issue is. So far he has fitted a new flow switch, that didn't solve the problem, the PRV has also been checked, put a new overheat switch in to stop it overheating and tripping...

The problem is in that when the shower is turned on (shower has thermostatic valves to control temperature), the radiators are getting hot even though the heating is switched off. The boiler has been descaled as well.

Phoned Worcester technical who are just plain useless and just keep speculating...first they thought it was a heat exchanger...then we realised this only happens when the shower is on..boiler keeps coming on and off which affects the hot & cold water i.e. it momentarily gets cold then warms up again when it fires back on.

When the basin and kitchen taps are switched on, the boiler remains on and doesn't go hot and cold but when the shower is on the boiler switches on/off and temperature goes hot/colder...the boiler makes these awful noises and the pressure needle quivers.

Does anyone have any clue what this might be...so far this is turning out to be a very expensive job as my plumber keeps tryng all these different things and he doesn't have a clue what could be the problem now...this particular model does not have a diverter valve...but somewhere along the lines, water is escaping to the radiators

HELP!!!

 

[bellairaphon]

Divertor valve

 

[bellairaphon]

^^^ assuming its the greenstar 24i

 

[begsy]

But this model does not have a diverter valve though...thats what the plumber said...

I don't know if it is the greenstar...

 

[Tom1981]

The 24i has a twin heat exchanger. If its scaled up then its going to have awful time transferring the heat over to the cold flowing water, this heats going to leak into the heating circuit. If its making a right racket when running a tap the heat exchanger or pipework would be my first point of call.

This is all if the burner pressure is correct, if its too high then it would also overheat.

 

[bellairaphon]

If you don't have an divertor it's just the 24i standard efficiency. The boiler going on and off is more probably the relay on the pcb that's faulty. Removing the bottom fascia and looking up on the board you will see the relay1 burnt out. You will also hear a ticking noise. This could be the the reason as when the relay drops out it activates the pump to disperse heat away from the boiler.

Nath

 

[begsy]

Thanks Nath and Tom....the only other thing my plumber was going to try was the thermostatic cartridge for shower..I just don't think that will resolve the issue.

The plumber has still not put the new heat exchanger in because he thought it was the shower thermostat that is faulty....then he thought it could be something to do with a circuit board.

2 accredited plumbers as well as my plumber and the worcester technical team can't find what the issue is...

I am not sure what to try now...

 

[bellairaphon]

Without been there I am unsure. My advice would be a fixed price repair. Or maybe one of the lads on here could have a look.

Nathan