Potterton Prima F Won't spark up, any ideas

**AndrewTi** · 14th October 2006, 17:51

Hi guys, it's getting colder at night and in the mornings and typically my boiler is on the blink. I can switch it on and the pump starts, the timer works too, but it just won't spark up and light. I had a little peep under the cover and there doesn't appear to be a manual striker? The gas hasn't been cut off as the oven and fire in the lounge still work!

Any help gratefully accepted!

**bobbyboy** · 14th October 2006, 17:55

if there is an igniter button, then you should be able to see a small spark when its pressed.......if there isnt one then you could need a new one mate....

**AndrewTi** · 14th October 2006, 18:05

That's what I'm saying, I had a peep and there was no sign of a manual striker!

**stickshift** · 14th October 2006, 18:48

Is it a fan assisted flue? If it is check it is spinning if it is not it will cut the gas supply as a safety measure they usually start to squeak when they are on there way out. If it is not that it could be the thermo coupler, they fail quite often but are only a few quid to buy.

**bobbyboy** · 14th October 2006, 19:20

Originally Posted by Andrew's SRi

That's what I'm saying, I had a peep and there was no sign of a manual striker!

out of my league now mate....better get the wallet ready......

**AndrewTi** · 14th October 2006, 19:25

Originally Posted by bobbyboy

out of my league now mate....better get the wallet ready......

Lol! Yeah, kind of resigned myself to that one!

**S888 SRB** · 14th October 2006, 19:40

Aint it always the way, no heating for a few months then you start to need it, fire up the system and whammo somethings wrong...

If you do have to call someone out lets hope its not a rogue trader!

**Caterman** · 14th October 2006, 19:41

Right, i'll try my limited knowledge that i have picked up from mates that are domestic gas fitters ( i'm CORGI but commercial )

The fan should be working, if it is'nt the PCB will not get a signal. If the fan is working there is a pressure switch that senses the air pressure from the fan. If this switch has gone, again, the PCB will not get a signal.
The PCB once it has a signal switches the ignition module on and opens the gas valve. The spark ignites the gas and a flame sensor takes over. This process is regulated by either the water flow valve or the heating controller.

Try switching the boiler off completely. Then urn it on and see if the fan starts up. As soon as it does there should be a slight click from the pressure switch. If there is it could be a PCB fault, if not it could be the fan is weak or the pressure switch is knackered.
It could be a few things so it might be safer to have it checked and serviced at the same time ready for winter.

EDIT: just thought of something else. There is a pipe from the fan venturi to the pressure switch, this could be blocked too! A simple blow down it clears the dust out. Don't blow towards the switch or you could damage the diaphragm in it.
Have you tried the reset botton in case it has tripped out.

HTH.

**AndrewTi** · 14th October 2006, 20:01

Thanks bud.

Must admit I lost you after The PCB bit! I'll have to get a man in!

Reset button? Didn't see one of those... not sure i heard the fan kick in either. I'll have another look tomorrow in daylight. It's dark and creepy in that cupboard!

**Swatty** · 14th October 2006, 20:06

Not sure if you have any of these on your system, I’ve had them fail a couple of times on mine. Apparently it’s a valve controlled by a stepper motor and if it stops working (there is one on the cold and hot pipes) the boiler will not fire up (I guess there is an interlink).

A temporary fix was shutting off all power to the system for a few hours and it came back to life again (but it will need replacing eventually). The gas engineer who came to fix it explained that you can manually open the valve with the small leaver highlighted in the pic – but I have not tried that.

Try the power off option and see if it helps