Quite urgent. Boiler keeps firing up even when Off

A question about : Quite urgent. Boiler keeps firing up even when Off

Hi

Please can someone help?

I have a Potterton Suprima boiler. I had set the hot water and central heating to go off at 0820hrs this morning, which it did (as in the lights on the control box has gone off and also the lights on the valves have gone off). The heating is definitely off though as the radiators have gone cold.

However, the boiler is still firing up intermittently, more than an hour and a half later and the pilot light keeps flashing green and after a while, it would turn amber (as if to switch off) but then it flashes green again. It fires up only for a little while and it doesn't stay fired up for long.

It is a Potterton Suprima wall mounted fan assisted balanced flue gas boiler.

Before I have to call out an expensive engineer, can anyone tell me what may be the problem?

Thanks for any help in advance.

Best answers:

• Frost 'stat kicking in possibly-is the boiler in a garage?
  Or faulty programmer?
  By 'pilot light', do you mean the power light?
• Hi
  Thanks for your reply.
  Boiler is in the kitchen.
  Pilot light is on the boiler, top right corner, power light?
  x
• Not the Domestic Hot water Pre-heat function ??
• Till the experts on here come back ,try this thread to see if it sounds similar
  https://www.greenbuildingforum.co.uk/...cussionID=9714
• Is there a separate programmer, if so what is the make and model?
  Pilot lights have not been fitted to boilers for many years now, they use electronic ignition. Many have a small green light to indicate that the boiler is powered up but not necessarily burning-that usually is indicated by a small blue light.
  If the boiler is trying to light with the programme timer at 'off,' then the programmer must be faulty (or the time on it is incorrect). Unless, as I mentioned before, the frost protection 'stat is kicking in (normally that will operate at around 5C). How cold is the kitchen?
• My boiler, admittedly an oldish one, usually sounds as though it comes on again after the programmer turning it off.
  What happens is that after turning off, the residual temperature in the boiler rises... because the internal fan is off.
  This temperature rise causes the fan to run to reduce the temp.
  When the temp. drops the fan stops.
  Some time later, say 10 mins, the fan will cut in again as the temp inside the boiler has risen again.
  This cycle continues until the internal temp remains below the trigger point for the fan.
  Sounds a bit like the boiler starting but it's not.
• I possibly had a similar problem with my old boiler. If I ran the hot water tap, boiler would keep firing (potentially for hours) even after I'd shut the tap off. If I then tried to put the heating back on, it wouldn't work (heating side).
  In my case it was a sticking pin linked to the diverter valve meaning the boiler constantly thought there was a demand for hot water.
  Unfortunately I can't give you an estimate of cost to fix (if its the same issue) as I ended up going for a new boiler - my boiler was very old and kn*ckered and had had to be nursed through the previous 18 months.
  Fortunately, until I got the boiler replaced I was able to use the flat edge of a knife to push the sticking pin back to reset the diverter valve after I used hot water so I could use the heating if required. Although I never trusted using the timer during that time.
• The programmer/control panel is separate and is a Potterton EP2002,
  Think I know the problem now after consulting the helpful neighbour who has the same boiler. So it looks like a faulty programmer and needs replacing.
  Thanks for your help everyone x