Any ideas on this one guys.

Central heating has been gradually deteriorating in performance since Xmas last few rads on the circuit taking literally hours to get warm. Was really bad this morning, only upstairs rads warm & boiler "cycling" very slowly staying off for 5 mins or more at a time, so water /rads never really geting hot.
Thought it was a flow problem so drained down & flushed the system - some cr*p came out but not a lot removed considerable amount of disgusting debris from the header tank. Have now refilled & bled the system, put boiler back on, pump is running, thermostat is calling for heat but boiler has not fired up. Tried killing the power to the whole system & turning back on - still the same, (potterton suprema 80 - it had the circuit board upgrade a little over a year ago) boiler light is flashing green which apparently means the boiler temp is satisfied - any ideas to persuade the b*oody thing back to life?

do you have to manually light the pilot flame? usually a button and it goes click click click...

If it has a wee window you should be able to see it

a linky to a forum

another forum

my boiler had 3 boards in 12 years

have a look on google, you'll see these things come up all the time

[Edited on 9/1/09 by Mr Whippy]

No it's all automatic electronic ignition etc.

if it is the same as or similar to my Potterton Combi 80 (also called a Puma), the wax capsule in the diverter valve fails about every two year giving the symptoms you describe.
Basically, the diverter valve stays in how water mode and does not allow any (or not much) water to flow to the radiators). The Boiler cycles since it overheats and the cutout triggers.

LOL another boiler problem!!

I have suprima 60; no hot water and then the CH started to play up - the gas will light, say on for say 5 sec, then go off, then the red LED would flash.

gas people came round to replace the vavle motoir - was stuck in CH mode. and replaved the controller to the latest model - had the motor/valve replaced less than 2 yts ago and the pcb replaced about 4 years ago.

gas mand said these boilers have no end of problems .... not what you wanted to hear.

what I fitted to my house, no hastles or bother, no need for a service engineer either -

the one in the stand alone garage is controlled from inside the house too and no wires

linky doo

[Edited on 9/1/09 by Mr Whippy]

sounds like the pump if upstairs is hot and the boiler is up to temp even if the pump is spinning it might not be spinning enough is the pump really hot?

pump is stone cold as is the rest of the system as the boiler won't fire at all. Pump was replaced just over a year ago - Grunfoss - i can hear it buzzing away & have tried all 3 speeds to no avail - surely even if there was no flow the boiler should fire up once b4 deciding it was up to temp?

I guess I didn't read all of your post. If the pump is cold and it won't fire up, then I don't think it is the diverter valve.

My Potterton bomes with quite a good manual that has a flow char for troubleshooting. Does yours have one and if so, you could give it a go.

Yes, it's got one but doesn't cover anything with the green light flashing as normally that just means the boiler is in its cooling down cycle.

the procedure for tracking down a fault basically involves checking each of the following (with a volt meter)

is the unit switched on and set for central heating
is the timer set to allow heating
does the room thermostat indicate heating is required
check that the flue fan is operating
check that the flue fan pressure sensor is indicating that the fan is working
....
....
and so on for each device that controls the system. Eventually, you will isolate a faulty component. If all the sensors are ok, then the control circuit board may be faulty.
If the board seems faulty, inspect it visually for faults. I have had to re-solder two dry joints on mine.

Eventually, you can find the fault through logic

Had this problem on a job at the beginning of december! Fitted new pcb upgrade kit and all was well for 10 days then it would only get luke warm and then packed up completly 1 hour later after waiting for Pottertons tech line I got sorry it looks like your PCB has failed!!!!!
And what did they do about GASH ALL had to buy another and wait for the credit after it had been sent back for testing!!!!!!!!!

All i can say is good luck OR bin the suprima ALWAYS have been and ALWAYS will be a pain in the arse for reliability.