Potterton Suprima 80 strange problem

[Shin10]

Hi,

We have recently moved house and there is a Potterton Suprima fitted.

When the thermostat is active and calling for heat the boiler works fine, heating the radiators. The hot water also works fine.

But when the thermostat kicks out, or I turn the heating off, the indicator will start flashing red rapidly, then it will start flashing green/amber (air proving and ignition), the pump will come on and then the fan, after a few seconds this will stop and the red light starts again before repeating the process every couple of minutes or so.

Anyone have any idea what this could be?

Boiler also doesn’t reset.

Thanks

 

[stem]

I think the flashing red light is just a lockout indication which might be caused by various possibilities.

One might be be the boiler's overheat thermostat operating. When the boiler goes off, the water inside the boiler continues to be circulated by the pump for a few minutes to cool the boiler down. If that doesn't happen for any reason, then the boiler overheats because of residual heat and its overheat thermostat operates.

Usually this happens because there is insufficient circulation through the system to get rid of the access heat. Much will depend on the type of heating system connected to the boiler. An S-Plan system (two port motorised valves) requires an external by-pass to allow the aforesaid circulation, These valves are adjustable and can be closed too much so that flow is restricted stopping sufficient circulation. With a Y-Plan (three port motorised valve) the valve itself provides the by-pass function.

Another cause is incorrect installation of the pump or faulty PCB that controls the pump, so that is doesn't continue to run after the boiler goes off. Can you check to see if the pump carries on running for a few minutes when you switch the heating off?

 

[Shin10]

Yes pump appears to run for a little while after the heating is switched off or the thermostat kicks out.

We had been running the system “on” all the time and using the thermostat to control the temperature but I decided to start using the programmer the other night and that’s when I noticed the problem, as I could hear it going through cycle when lying in bed but obviously it shouldn’t have been on.

I watched it before and it went off when thermostat kicked out, pump ran for a little while then stopped but it didn’t go into lockout. Just came back on normally when thermostat kicked in again.

Could it be the programmer?

 

[stem]

Unlikely to be the programmer it's just a switch; it's either on or off. And in your first post, you said the same thing happened when the thermostat 'kicks out'

You could try running the boiler at a lower temperature for a while just as a test, if it is the overheat and it's borderline tripping, you might find it's OK, if it is that could be a pointer. Of course it may still go into lockout, which wouldn't prove anything.

 

[Shin10]

Yes sorry when I was testing last night the sequence would start either when heating was turned off completely or thermostat was upto temperature.

This morning when heating was on it appeared to be operating correctly, boiler would shut off, pump would run for a little while and then stop. No flashing red light. After a while it would fire up, I would imagine when thermostat called for heat again.

I will continue testing today. It’s just bloody annoying lying in bed and it going through this sequence every few minutes.

Thanks for you help

 

[BlueLoo]

Suggest this is a bypass problem.

Probably caused by fitting a new PP pump or the bathroom rads have been turned off.

Your pump is dead heading when your zone valves close.