Potterton Profile 60e tripping overheat after 15 minutes

[birkarhino]

I've trawled through a heap of forum posts on the 60e before but this issue doesn't seem to have come up before (apologies in advance if it has and I've missed it).

My boiler starts up fine and heats fine but trips the overheat after 10-20 minutes. Hot water and radiators all fine until the trip.

Some background: after a period of disuse, I had put in a new pump and 2-way valve and changed the (leaking) hw cylinder. When I did all this I drained, flushed and bled the system.

I suspected the boiler stat and changed that too but it didn't cure the problem. The logic board doesn't seem to recognize any boiler stat setting bar 'off' - the detented position on the rotary that opens the circuit.

Now I suspect the PCB but as it's 140 quid I thought I'd ask the experts here first before shelling out all that when it might be something else ..

My speciality is computers, networks and software. So if I can help anyone in return, put a post in the right forum, let me know what you called it and I'll do my best to answer)

/Simon

 

[bengasman]

Could be lack of flow due to blockage, not enough pump capacity, pump installed wrong, boiler stat, valve wired in wrong, and probably a few more.

 

[HERTS P&D]

Air lock? Have you bleed all rads and pump?

What you can do is turn on the boiler and turn the pump speed up and down, while the system is running, this normally removes any trapped air. You can heard it going round as you do it.

Andy

 

[scoobydo123]

Does this boiler have a pump overrun? Could be that this has failed and when one of the external controls is satisified and the pump turns off rather than continue to remove heat from the HE.

 

[45yearsagasman]

It does have a pump o/run.Just one thing though,to change those components(boiler stat) you have removed the front cover and the fan assy.I hope you know what you're doing.Positive combustion chamber which needs to be checked for correct sealing.

 

[birkarhino]

bengasman: the pump's a new one and a direct replacement (model, fitment orientation) of the one that had been working fine for twenty years. boiler stat is new.

HERTSDRAINAGE2010: yep, done that - bled all rads and cycled the pump speeds till I couldn't hear any blooping, gulping and tinkling of air bubbles in the system.

scoobydo123: perhaps I'm misunderstanding the PCB logic? I thought the room thermostat controlled the pump (when allowed to by the timer) and that the the boiler would fire when the pump was running and the input water temp was below that of the boiler stat setting?

45yearsagasman: thanks for the warning. Isn't the 60e fail-safe though? That is, doesn't the PCB inhibit the gas valve if the fan doesn't make enough positive pressure in the combustion chamber?

/Simon

 

[45yearsagasman]

No!! The 60e will operate with a faulty combustion cover seal and the safety devices are crude. Combustion products will still be emitted with a faulty seal....Do you feel lucky?