Potterton Potty Performa 28 Help needed please

[montur]

hello i'm new to this, hopefully i will have explained myself well.

i have a potty performa 28 installed 3 years ago. yesterday it decided to stop working and the fan warning light is flashing. i have followed the fault diagnosis in the manual and looked at flow diagram D.

The pump runs but the fan does not.

I tested the mircoswitches for continuity and their relevant number on the PCB and they both function ok.

The central heating stat (temperature sensor) has a resistance of 13.62k ohms at 8 degrees celcius.

There is no voltage to the fan, and on the PCB A2 connector pins 5 and 7 have no reading were it should be 230v.

On switching the heating on the fan blade twitches a little but does not continuously spin. The blades move freely and all together so the fan is not jammed.

I can't see anything burnt on the PCB. The flow diagram suggests replacing the PCB.

Before i order a new PCB is there anything else i should check and test

 

[Soggy_weetabix]

Yes,

Find the overheat button (should be l/h/side) when pcb panel lowered.
Red I think?

Try to push this button in, and if it 'pops' back in, that is your problem

David

 

[Agile]

Except that something made it overheat!

Did you by any chance allow the system pressure to fall to zero ???

Tony

 

[gazthepottertonengineer]

2 things first make sure you turn power off before trying to reset

also they have a habit of popping out every now and then so dont worry too much if pressure hadnt dropped

 

[montur]

Thanks everyone for the quick responces. When i looked the pressure had dropped by 0.5 bar so i filled it up again. I will try and check what has overheated and let you all know the outcome.

 

[montur]

There was no red button i looked everywhere the manual does not mention it either. I have seen this button on other boilers but not on this one.

I tested the overheat thermo and it has continuity at 8 degrees with a resistance of about 0.05 ohms, is this right????

. there is a reset setting on the board knob i tried this and still its the same problem.

I have taken some photo's if someone could point out where the overheat button should be. If its not there i guess i will order a new PCB.

p.s. how do i add a photo?

 

[kevplumb]

the reset button is on the pipework on the left if you drop the front panel

 

[montur]

what does it look like please? size, colour? thanks

 

[kevplumb]

silly question i am sure you have try'd the reset position on the selector switch on the front

edit

just noticed the one in the spares listing dose't have a button on

 

[corgigazza]

Have now replaced 3 pcb's with the same fault as yours (28/28i) fan twiches then stops, even making aps does not bring it on.

These boilers were 2 -3 years old

 

[Agile]

The o/h stat clips onto the flow pipe on the left below the combustion chamber.

It has two male spade connectors and a dark red "button" in between the spade connectors. To reset it IF it has tripped you push in in with an insulated rod such as a ball point pen.

Dont use a pencil as its graphite "lead" is a conductor and can give a lethal shock if touched onto a live connector!

Tony

 

[kevplumb]

according to the book FWIW

the 24 has a button the 28 doesn't

that's what threw me

 

[montur]

Thanks for all the comments. I have ordered a new PCB for £80 inc vat and postage i should receive it on Thursday and will post the outcome.

 

[montur]

got new pcb this morning, installed it and held reset as instructed for 3 seconds. this time fan light is off but overheat stat on and flame light on . went and bought new o/h stat still same problem . phoned potty the said hold reset for 30 secs if light dont distinguish then board faulty. did so and this new board must be faulty . awaiting replacement board.

 

[montur]

got new pcb this morning, installed it and held reset as instructed for 3 seconds. this time fan light is off but overheat stat on and flame light on . went and bought new o/h stat still same problem . phoned potty the said hold reset for 30 secs if light dont distinguish then board faulty. did so and this new board must be faulty . awaiting replacement board.