Potterton Profile boiler question

[cliffjb]

Hi there

I've just moved to a new house which has a Potterton Profile 40e boiler. All seems to be working OK but if I want to switch the hot water on I need to select '0' on the dial and the boiler fires up. If I then move the dial to past 2 in order to get hotter water, the boiler turns off. Any ideas what's going on and what I need to do?

Apologies if this is a daft question but this is the first house I've had with central heating, boiler,etc.

Cheers
Cliff

 

[JohnKay]

Hi Cliff
Do you mean the boiler thermostat dial, or something else, The grey knob on the font of the boiler ?

The boiler should not fire on '0'

I wonder if the knob it's self is damaged, and slipping on the spindle.

please let me know if this is the control you are referring to.

 

[cliffjb]

Hi John

Yes, the knob on bottom front of the boiler numbered from 0 to max. With the switches in 'on' position the boiler fires if I turn to 0 then switches off if I turn past 2.

The knob itself seems perfectly stable and twisting as I'd expect..

Cheers
Cliff

 

[JohnKay]

I'm a bit mystified here, I've installed, and worked on a great many Profiles, and never come across this problem.
So I've just got to clear one thing. The numbers are visible through a slot in the sloping plastic bottom panel, right ? Does the knob turn back past the '0' or on beyond the 'Max' There should be a positive stop ?

 

[cliffjb]

Hi John

Yes, the numbers are all visible through the slot on the dial, 0 being the uppermost point and turning clockwise up to max. The dial seems, to me, perfectly normal and turns as expected

Cheers
Cliff

 

[JohnKay]

That can only mean one thing then - Defective thermostat. There is no way the boiler should fire when set to '0'
Sorry to say, this is not a DIY job. I would suggest you get an approved Gas Safe engineer to take a look, British Gas maybe.

I just wonder how the previous occupier managed with it !

Lets know how you get on.

 

[JohnKay]

Got it !
Scrub that last post - The thermostat has been incorrectly wired. it incorporates a pump overrun device, the wires are on the wrong terminals.

Took me a while to think that one through, I'm only going on memory, now retired.

 

[cliffjb]

Hi John

Thanks for your input on this. As I am as technically gifted as an untrained monkey when it comes to this sort of thing, I guess I will have to get someone to have a look at it and sort out the wiring.

Cheers

Cliff

 

[JohnKay]

Thanks for the feedback Cliff.

It's the only way forward. If I were doing the job, I would be checking the wiring first, followed by the thermostat, and the printed circuit board.

What makes things difficult is that you have no history of the problem, or knowledge of how it should work. As I say, I can only work from memory, not like being there.

Slight warning - parts are expensive !

 

[cliffjb]

Cheers John...