My poor Ravenheat HE85

[thattallman]

Hi guys, I'm really hoping someone on here might be able to help me out.

This morning I noticed the red flame/temp light illuminated on my boiler and I couldn't get hot water or central heating. I reset the boiler and all seemed fine; until this evening. I noticed the place was quite cold, even though the heating should have been on. When I went back to look at the boiler, I noticed it was continuously firing up, over and over again. The hot water seems to work perfectly fine though.

The fan will start, so will the pump, the gas flow and ignites. Then after a few seconds, the fan will shut off, then maybe 10s later, the gas will cut off. The whole thing repeats itself over and over. I have checked the thermistor which is in tolerance. Reading over the forums I'm beginning to suspect it could be the fan PCB - I just need someone to give me the confidence to order it.

Is there anything else I could check?! Andy advice appreciated.

Best regards,
Andy

 

[Agile]

I very much doubt that it could be the fan PCB.

But I do think you want a competent RGI and many don't like working on that make/model.

Tony

 

[thattallman]

:\ .. Okay, so I took the fan PCB out and realised how simple it was. It just uses a few capacitors to bring the voltage for the fan down after venting the combustion chamber. I checked the relay was operating correctly, though found when it switched to the low power mode, there was no output.

Since there isn't much on the board, I've just ordered a bunch of like-for-like capacitors. Spoke to my uncle (who fit this unit for me 4 years ago); he's had dozens of these boards fail recently. Apparently Ravenheat have released a redesigned board for this unit which doesn't suffer the same fate. I've pilfered another 3 boards from my uncle to repair and test in my unit.

Ideally this unit should use a transformer to reduce the voltage for the fan - something to think about in future.

For anyone else reading this thread, the parts I've ordered from CPC are below. I've got enough to do 5 units. In hindsight, 400V caps would have been better - sure the heat is degrading them.

1 x ECQU2A474ML - 0.47UF, 275V
2 x ECQU2A105ML - 1UF, 275V

 

[thattallman]

Just in case it's any help. I've temporarily bodged this as the caps wont be with me until Wednesday. I've simply soldered a thick piece of wire as illustrated below.

Andy

 

[transam]

Afaik the raven model prior to this one did not have a fan modulation pcb

the fan pcb was added in order to maintain an A (effiency) rating , along with a specific APS

So if the fan pcb was added to the existing /same electrics as the boiler with out the fan pcb than ??

 

[thattallman]

Just a quick update. Capacitors replaced and all is working well again - for now!

Cheers guys,
Andy