Prima 40F boiler

[Ashy_2008]

I posted about a week ago for a problem with my boiler. I now have more info and hopefully someone can help me out.

The boiler is a potterton Prima 40F - The fan comes on only for a few seconds and then you hear a tick and it goes off. It then comes back on in a cycle and maybe after 10 or so minutes it ignites.

I've had an engineer out who has checked the fan, the air tubes and has changed the air pressure switch and this has not fixed the problem. He suspects it could be the PCB but Potterton have said they don't think it's the PCB and is probably a corroded flue.

It doesn't seem like the fan is on long enough to create a vacuum and activate the pressure switch. Once it sparks it ignites fine and runs until things are upto temperature.

How can I check the flue and what would I be looking for i.e. holes? Any advice or toher suggestions appreciated.

 

[Rob]

PCB. Potterton should know this by now!

If you give the boiler a gentle tap underneath it will get it to fire up, untill it turns off again.

 

[LUNAT]

HI

i would go for PCB flue is unlikely to be corroded

manufacturers hardly give correct advice

 

[Ashy_2008]

Checked flue and its clear and not corroded. Before I buy a board tomorrow just one last question -

If I remove the red air pipe from the fan, the fan will then run continously. The boiler doesn't try to fire because there's no vacuum. The red pipe connects to the top of the fan unit. the other clear pipe connects just above it and then that goes to the inner pipe in the flue.

Where does the red one go to in the fan? Could something be blocked in here? When I here the ticking noise its as if the vacuum switch is knocking off, which would indicate a problem where this pipe goes rather than the pcb?

Is there a sensor or anything where this red pipes connects to that I could try cleaning or replacing before spending £150 on a PCB?

Cheers

 

[twgas]

PCB........even had same problem on my own boiler, with same cure!!!!

 

[Ashy_2008]

Ok thanks. Is it straight forward to swap the PCB - just a few connectors?

 

[Ashy_2008]

Changed PCB, cost £130 inc VAT - Back in business.

Thanks for your help... Local Corgi guys wanted £270 to fit this part

Thats like £280 per hour, it only took me as a novice 30 mins to do...