Potterton 30 boiler flashing amber (calling heat) but doesn't ignite

[kmr]

Hey guys

I have just purchased a house and when i turn the 24hours button on the timer for the CH the potterton boiler calls for heat (flashing amber) but doesn't respond (fire up) however, a few hours later if i try it then it does or may not.
Also I set the timer (honeywell) for the boiler to come on but also flashes amber when it hits the times but again doesnt ignite.
I am thinking either the honeywell programmer is faulty or something wrong with the valve?

Any help? thank you

Potteron Suprima 30 boiler
Honeywell programmer (on the wall, underneath boiler)
British Gas thermostat (dial in the hallway)

 

[ollski]

Pcb usually but can also be a sticky air pressure switch. Does the fan run?

 

[kmr]

I thought originally the PCB could be at fault but the boiler does come on sometimes. Does that matter or can a faulty PCB still turn the boiler on? How would i know if the fan comes on ? The steam comes out the flue outside. I know that for sure.

 

[Allen1]

Can i ask a really silly question please? (If there is such a thing) Should a Potterton Suprima 50L always ignite when there is call for heat from the heatstore (ie sw live becomes live 240vac), and go out when SW voltage becomes 0vac. Thank you in advance for your replys.

 

[picasso]

Your boiler has an anticycle timer so it might not always ignite on call for heat, boiler also has pump overrun so although flame goes out pump may continue for a while, why do you ask ?

 

[Allen1]

Hi Picasso, Thanks for such a fast reply. The boiler locked out the other day, I reset and all seems well now. We had this a few years ago and our plumber correctly diagnosed a PCB fault, he upgraded the circuit board as apparently this was a common fault for the type of boiler, everything has been fine for ages. As this looks like it could well be the start of a similar problem I have started to observe the boiler and heatstore behavoiurs. i made the assumption that when the heatstore asks for heat the boiler will always provide it. So its join British Gas Homeserve or get the plumber in, Thank you.