Potterton over heat thermostat

[okneedhelpplease]

Hi again all i have a potterton performa 24 and the overheat stat keeps clicking out and i have to push the little button in on it to reset. It only happens when the hot water runs but not all the time.

Anyone help please

 

[powell30]

It's overheating

Your plate heat ex is most likely sludged or scaled. Clean or replace

 

[echoes]

I had exactly this problem with a similar Potterton. The clips which should hold the thermostats to the return pipe inside had both bust and the stats were just flapping around inside. Worth checking.

 

[Agile]

That last post is not logical !

If an overheat stat is not in contact it cannot trip because its not being subjected to the heat in the flow pipe.

The first reply is the one to follow up as its a blocked plate HE.

Tony

 

[echoes]

That last post is not logical !

If an overheat stat is not in contact it cannot trip because its not being subjected to the heat in the flow pipe.

The first reply is the one to follow up as its a blocked plate HE.

The 2 stats not in contact were the control stat on front of boiler and the pump overrun stat. I didn't mention that the overheat stat was attached & functioning (should have done).

So the only stat functioning was the overheat stat.

Logical now?

Sorry for not being clear

 

[okneedhelpplease]

thank you for all the replys, but please tell me, how do i clean the heat exchanger.
O did i mention it only happens when the hot water is switched off. For example if we shower its fine but when we turn it off it trips

 

[petit_pablo]

That last post is not logical !

If an overheat stat is not in contact it cannot trip because its not being subjected to the heat in the flow pipe.

The first reply is the one to follow up as its a blocked plate HE.

The 2 stats not in contact were the control stat on front of boiler and the pump overrun stat. I didn't mention that the overheat stat was attached & functioning (should have done).

So the only stat functioning was the overheat stat.

Logical now?

Sorry for not being clear

performa doesn't have a pump overrun stat and control stat is connected to board. Thermsistor is screwed into primary flow pipe.
Are you thinking of profile?

 

[Agile]

thank you for all the replys, but please tell me, how do i clean the heat exchanger.

O did i mention it only happens when the hot water is switched off. For example if we shower its fine but when we turn it off it trips

That is a classic description of a primary heat exchanger which is scaled with lime compounds.

It can be cleaned in situ with hot sulphonic acid ( DS3 ) but is messy and has to be done by someone who knows what they are doing.

If it were removed by a gas engineer then it could be cleaned with sulphonic acid or HCl. Again messy and somewhat risky working with acids.

Not what I would recommend as a DIY job !

Tony

 

[okneedhelpplease]

thank you all

 

[echoes]

performa doesn't have a pump overrun stat and control stat is connected to board. Thermsistor is screwed into primary flow pipe.
Are you thinking of profile?

Yes petit_pablo, you are spot on - mine was a profile. Thought it was worth a quick post just in case the OP's control stat sensor had become unattached, but thanks for putting me right.
Good that Potterton ditched the flimsy clips in favour of screws

 

[Andygasman2010]

Ahh the confusion! Performa and profile are very different boilers. If it's tripping after the hot water has satisfied then i'd look at the pump overrun facility or the bypass on the system.

Check that when demand ends the pump continues to run.