Ravenheat CSi85T

[Vinno]

I have the above boiler but the DHW is not getting very hot. The PHE was cleaned 2 months ago and the thermistors and poteniometers have been replaced. It was working fine untill 2 days ago.

I can see thru the sight glass that the gas only comes to full power when I unplug the DHW thermistor but it then goes on to get to hot and then cut out. I also note that if I press the screw end, which is concealed by the yellow cap on the gas valve, the gas appears to come to full power.

Any ideas what the problem might be?

 

[clf-gas]

Change the DHW thermistor seems faulty.

I Know you said it has been changed, but new parts can be faulty also.

STOP pressing the self destruction button...... you crazy guy..

 

[Vinno]

Thanx Craig but tried that and no luck. Anything else?

 

[ChrisR]

COuld be faulty gas valve or pcb (or something else!). Someone needs to measure mod coil voltages and gas pressures. Would probably be a corgi...

 

[clf-gas]

Might not be thinking clearly hear (been painting and drinking).

does'nt the thermistor modulate the gas by way of resistance?.


Whats the boiler doing on heating vinno?.

 

[ChrisR]

does'nt the thermistor modulate the gas by way of resistance?.

Sure, indirectly, but as the guy's changed it twice...??

It's the pcb which measures the resistance of the ntc, & decides what voltage to put on the mod coil. If say there's a HW control on the pcb with a broken track, gawd knows what you'd get.
Gas valve solenoid could be sticking I spose, though if it's been poked that might clear it!

 

[Vinno]

Heating not on its DHW thats the prob. Poking the solenoid sounds like a plan. Any pointers wecome!

 

[clf-gas]

Thats my train of thought Chris, (points toward PCB emoticon)

Looked at my CSI manual(PDF) and cant read it, too blured.