Potterton boiler locking out

[Whoozit]

Potterton MF RSL 100 which is c. 10+ years old. It's now locking out after 90 minutes-2 hours of use, however can be reset once it's cooled off a bit/some time has passed. Plumbers have been round and can't find anything obviously wrong, and have replaced both the main electronics black box and the pump.

Any knowledgeable ideas welcomed

[TvrJohn]

Have a search on the DIYnot.com website, loads of info on there

[silversurfer1]

You sure its a RSL model and not CFL as the CFL has a flue stat that will knock out the reset if its faulty or you do indeed have an issue with the flue the RSL does not have this.

If indeed you don't have a circulation issue then you can check the resistance of the overheat stat, sometimes these break down and go open circuit with temperature rise and can be difficult to catch.

I don't remember if that model locks out on ignition faliure you could isolate the gas and fire the boiler if it locks out then you plumber may be barking up the wrong tree looking for an over heat situation when in fact it is an ignition issue i which case check pilot flame / electrode condition position / HT lead condition / working pressure / soft light pressure and burner pressure /

also check fan is not breaking down after a while and or air pressure switch is not dropping back

good luck

ss

[ladderino]

May not be remotely related, but I have a Potterton Profile 80, and find that unless the boiler control is set to a pretty low temperature it will lock itself out.

As I found this morning, when I woke up to a freezing cold house.

[Whoozit]

silversurfer1 said:

You sure its a RSL model and not CFL as the CFL has a flue stat that will knock out the reset if its faulty or you do indeed have an issue with the flue the RSL does not have this.

If indeed you don't have a circulation issue then you can check the resistance of the overheat stat, sometimes these break down and go open circuit with temperature rise and can be difficult to catch.

I don't remember if that model locks out on ignition faliure you could isolate the gas and fire the boiler if it locks out then you plumber may be barking up the wrong tree looking for an over heat situation when in fact it is an ignition issue i which case check pilot flame / electrode condition position / HT lead condition / working pressure / soft light pressure and burner pressure /

also check fan is not breaking down after a while and or air pressure switch is not dropping back

Cheers, all good leads to chase. Definitely an RSL.

[Whoozit]

ladderino said:

May not be remotely related, but I have a Potterton Profile 80, and find that unless the boiler control is set to a pretty low temperature it will lock itself out.

As I found this morning, when I woke up to a freezing cold house.

Ta, I will try that overnight.