Main 24HE Central heating problem

[gasfun]

Hi Guys
Boiler fires up in hot water mode with no problem, but in ch/ hw mode ignition but gas valve doesn't fully open.
I have checked:
-diverter valve (new replacement kit)
When I opened the diverter manifold there was only one spring in it and there where two in the kit. I've fitted both springs. I pushes the ch diff pin out into the microswitch on top of the ch diff valve
-pump works
-micro switch on ch pressure diff valve
I have checked for resistance on the switch and leads to the pcb

Any ideas?
Thanks

 

[moogwai]

Have you checked injectors on burner.... Had a similar problem the others day on a ferroli which needed cleaning. Could also check voltage to gas valve to make sure pcb is sending enough power to valve...... Dont know the correct voltage though.

 

[gasfun]

Moogwai, the problem is that it fires up in hot water mode with no problem. Burner pressure is fine. I just think it needs to be a problem with the micro switch on the central heating diff valve or diverter valve. I am not sure if I made a mistake when resembling manifold.
I will check the injectors on Tuesday. left the boiler on hot water mode- seems to work fine

 

[ambrosia]

If i was to guess which i'am i'd say gas valve or pcb (or possibly wiring loom)

check the pcb is sending the correct signals as moogwai says, wouldnt worry about voltage if theres a detectable signal its probably right,
if pcb is sending signals i'd be looking at gas valve

micro switch is easy to test with a screw driver, just switch it up

 

[gasfun]

I have already replaced pcb. would the gas valve play up in ch mode, but work in dhw mode?

 

[zeebeedee]

Ch stats in range?

 

[gasfun]

Room stat? Not one fitted

 

[jefaz]

Does the boiler try to spark?
have you checked the minimum burner pressure?

 

[gasfun]

It does spark and ignite but die down immediately there after. Minimum burner pressure is fine. But still: in hw mode it fires up and works fine

 

[stoker122]

Have the HW and heating circuits got separate thermistors regulating the burner?

 

[gasfun]

Not that I am aware of. One termister and one overheat stat and one flue stat

 

[mountainman]

It does spark and ignite but die down immediately there after. Minimum burner pressure is fine. But still: in hw mode it fires up and works fine

I had that problem recently it was the pcb.

 

[gas frank]

Have u checked the APS, think I seen this before where the hw was ok but ch would not work turn out to be the APS.

 

[gasfun]

Cheers for that. Will check it out on Tuesday and let you all know what was the answer.

 

[gasfun]

Went to boileve r today. Check minimum burner pressure and adjusted it to mi's. Boiler works fine now. also: the return isolating valve was only partially open-plastic tap warn. as soon as I opened it fully everything seemed to work. Rads nice and warm, hot water nice and hot! Job done
Thanks guys