Pott Prima 60 won't fire up, any ideas?

[Will100]

Hi,

My heating engineer suggested I ask on here if in case anyone can suggest anything new to try. I have a Prima 60F that stopped firing up about 10 days ago (just as it got really cold typically). I'm now sitting in the cold typing this to try and garner any suggestions, before the next step of getting a new boiler installed.

So far we have:

Replaced the PCB (twice for good measure)
Replaced air pressure switch
Replace fan (bearing was suspect).

After fitting the new fan the boiler ran for a hour and then stopped igniting. Now the PCB never supplies the fan with 240v, so the pressure switch never operates, hence no go. This is now the third PCB so I doubt all have been faulty. The switched live does seem to go live once the call for heat is made. You can hear the pump operate as expected and it makes all the right noises.

Any new ideas as to why the PCB doesn't put 240v on the fan terminals would be most welcome as I sit hear shivering! My engineer is giving it some thought too, but your collective brains and experience might uncover something he hasn't through of.

Thanks a lot!

Will

 

[slapper]

Has he tried taking a seperate 240v to the Fan to see if ignition sequence begins?

 

[wetshoes]

Check for faulty overheat thermostat

 

[nickso]

Check for faulty overheat thermostat

That would be my guess, if not use the pretty decent wiring diagram on the plastic undertray.

 

[Will100]

Thanks for the quick responses, we took a separate 240v to the fan and it did go into the ignition sequence. Now here's the really stange part...after reverting back to the PCB for the fan supply the fan then did start up and the boiler ignited after about 30 seconds. Using a meter there was nothing coming from the PCB to the fan before, and now their is, but it wasn't touched in between times!

We are running the system up now to see if it's cured or just a lucky glitch, fingers crossed! Room temperature in the kitchen is now 9 degrees and climbing!

Thanks for the suggestions, the overheat stat had been checked previously and was said to be ok.

Cheers,

Will.

 

[cardinalfox]

Hi,

My heating engineer suggested I ask on here if in case anyone can suggest anything new to try. I have a Prima 60F that stopped firing up about 10 days ago (just as it got really cold typically). I'm now sitting in the cold typing this to try and garner any suggestions, before the next step of getting a new boiler installed.

So far we have:

Replaced the PCB (twice for good measure)
Replaced air pressure switch
Replace fan (bearing was suspect).

After fitting the new fan the boiler ran for a hour and then stopped igniting. Now the PCB never supplies the fan with 240v, so the pressure switch never operates, hence no go. This is now the third PCB so I doubt all have been faulty. The switched live does seem to go live once the call for heat is made. You can hear the pump operate as expected and it makes all the right noises.

Any new ideas as to why the PCB doesn't put 240v on the fan terminals would be most welcome as I sit hear shivering! My engineer is giving it some thought too, but your collective brains and experience might uncover something he hasn't through of.

Thanks a lot!

Will

 

[cardinalfox]

will100 i have the same problem you had. did you overcome it.

 

[twgas]

Card...
you should start a new thread, stating your exact problem(s). I'm sure we will be able to help/advise you to a cure, but usually need some specific info.

 

[wills100]

Sorry I should have posted before...

The thing that really made a difference was the smallest thing. We replaced the short tubes that go to the air pressure switch and made sure they had a really tight seal (as well as clearing out the in-line restrictor). After that the boiler fired up every time. I noticed that even if there is the smallest of kinks in those tubes when you put the thing back together it will not fire up reliably. We also fitted the remedial flu kit from Potterton which made a big difference to the quality of the flame and i'm sure the rads are now hotter than before. Thirty five quid well spent for that.

Thanks to all on here who posted ideas and tips, much appreciated.

Will.