Potterton Puma 80 locking out

[rsmid]

Hi
I have a Puma 80 perm. pilot that appears to overheat and lock-out. In CH mode it lasts about 40 seconds before I hear a click and the pilot light extinguishes.
With the HW, I can run the water for as long as I like and it provides consistent nice & hot water but 5 seconds or so after closing the tap, I hear the click and the pilot extinguishes again. Once it has cooled slightly, it can be relit immediately.

The pump was replaced about 6 weeks ago and the whole unit given a service by the engineer at the same time. Although the heating has not been used much, it was working. The only thing I have done since the repair and service was to bleed one of the rads as I could hear it gurgling last week when the better half decided it was time to put the heating on.

So far I have:

Switched the pcb for a spare I carry (they seem to go every 2 years!)
Checked the pump is running and has no air in it
Drained the system (water was very clean) and refilled with inhibitor to 1 bar
Checked for dripping taps
Checked the red light when running HW to ensure DHW flow is closing promptly the tap is closed.

Does anyone have any ideas?

Thanks

 

[Agile]

It does sound as if it is overheating!

The only problem is that it does not point to any particular cause although there are several. Some are gas related which we don't advise on here.

The only think I could suggest that you could do is to turn of your pilot light for at least an hour and then measure the resistance of the CH and DHW temp sensors. Should be about 10k approx. Also check the connecting pins are clean too.

If they are correct then I would have to suggest that you call back whoever serviced it to see whats gone wrong.

Tony

 

[steve32]

Are the radiators heating when ch is on
is flow pipe near boiler hot when ch is on

 

[rsmid]

Are the radiators heating when ch is on
is flow pipe near boiler hot when ch is on

The CH is not on long enough to get the rads hot, however the flow pipe does get hot before the boiler overheats.

 

[Agile]

Have you checked the sensors???

If so you may need an engineer. Make sure you choose one who repairs boilers though!

 

[rsmid]

Hi Tony

Thanks for the suggestion. Will check them tonight - I got in late last night and wasn't in a state to start playing with the boiler

Rob