ravenheat csi85 wont fire up?

Hi, Please HELP me...

I have a Ravenheat 85A (T) combi boiler.  It will  not fire up.  

Already Troubleshooted:

1.  New Thermistors fitted.   (instruction Ravenheat Tech Guy) 
2. New Air Pressure Switch fitted.
3. New Low water sensor fitted.
4. Tested the fan and it works fine (without connected to boiler).  There is no break in the fan's live cable (brown)
5. Tested the Electrode and both are fine.
6. Pump is working fine.
7. The gas valve is also working great.
8. There is continuity on the overheat thermostats.

This combi boiler has one large PCB which controls everthing, including the fan.

The problem:  There is power to the pump from the pcb but no power to the fan when the boiler is switched ON.

When boiler is turned on there is live feed to the pump and the pump turns on, but no live feed to the fan direct from the PCB connector  (considering the fan is tested/working), after appox 30 seconds later the Red LED turns on and the boiler cut off completely (with solid green and red led).   Unless you turn the mains off and turn it back on the boiler is halted.  Resetting the boiler dosn't change anything.

However, with a bare wire when I cross connect the pump live feed (from PCB) to fan live (PCB connector) the boiler fire up working great for 5mins to 30mins and eventually cut out with a solid red led.

Does this means the PCB is faulty?  Or is there something else that I am missing?

You advise would be very helpful.

Thank you very much.

Kind regards

Jal
November 2011

my boiler was doing this , the fan was not turning at the correct speed ,before you call anybody out try spraying the fan shaft with wd 40 this worked for me.
common fault with this boiler the fan shaft dries out and sticks thus not operating the switch at the correct pressure.

trev.
November 2007

Hello mate,

I had the same problem with my boiler and it turned out to be the differential pressure switch in the flue. The switch is just near the fan at the top of the boiler. You can short the switch out on the side of the ignition pcb, though do check your flue to make sure it is not blocked.

Dave

Dave Seddon
May 2007

Sounds like a flue or air pressure fault. Not for the d.i.y..
Anything involving the inside of the combustion chamber require's corgi engineer... water faults are one thing but gas and fumes are too dangerous to mess with. Sorry.

T.H.S
April 2007