Potterton Promax HE Plus

[DP]

Boiler throws an E168 fault code (not mentioned in the MIs). HW LED is not lit. Faulting with the flowchart, PCB-X3 terminals 5&7 show mains voltage as if boiler is on HW demand; should be 5&6 for central heating. Flowchart says change PCB. Boiler is just over two years old.

Manually pegged the diverter, now rads are nice and warm.

Any suggestions guys?

Thanks in advance.

 

[powell30]

Technical says check fan, gas valve resistance and if ok then pcb.

In my experience, change the pcb

 

[Andygasman2010]

Yea it's usually the PCB but I did come across this once....

//www.diynot.com/forums/viewtopic.php?p=1594065#1594065

 

[Heating one2one LIVE]

Sounds mad but if you have any magnets stuck onto the front of the boiler then take them all off.This is an electric magnetic fields error(E168).
I read this on here some time back and it does work..good luck.

 

[DP]

Braders, I do not think a magnet on the outer cover will effect the boiler. This sillyness (me thinks) is thought up by someone who is clueless but wants to show he is clever.

Any magnet if attached, will most likely be on the white cover. The magnetic field around the magnet will now transfer to white cover but but will be much weaker. Not only that, there is another sheet metal cover that will further act as a shield. Metal sheet acts as a magnetic screen (use to find these on relays on electromachanical equipment).

Cannot see a magnet effecting relay operation where the pole face has concentrated field to pull in the armature. A megastrong magnet might effect relays if these were to pulse a signal like they did on strowger equipment. Relays on the PCB in the boiler are mear electrical switches.

Finally, the control panel cover has two magnets fitted on it by the makers.

 

[peterbaxi]

this is a pcb fault no doubt about it, ps i work for baxi and potterton

 

[Agile]

Cannot see a magnet effecting relay operation where the pole face has concentrated field to pull in the armature. A megastrong magnet might effect relays if these were to pulse a signal like they did on strowger equipment. Relays on the PCB in the boiler are mear electrical switches.

Wow! The old uniselectors!

The steel boiler case would concentrate the magnetic field through the cover and reduce penetration inside.

Proper magnetic shielding uses mu-metal. Like the 600H inductor of the audio circuit on the SCR522 aircraft tx/rx.

Tony

 

[Gasinayr]

I had the same problem and it was due to fridge magnets on the front casing. removed them and boiler worked fine

 

[Gasinayr]

Just to let you know DP. it was me that placed the post about magnets affecting the pcbs and you are way off the mark about me being silly and clueless. I have 25 years with scottish gas 16 years self employed also service agent for Vokera ( before they dumped us all ) service agent for Valor ( until they were taken over ) and still going strong As for the magnets I have called back to this job a few times to recheck and its still working ok.

 

[Agile]

The magnets on the outside could affect any Hall effect sensors in the boiler.

What Hall effect sensors does this boiler use?

Tony

 

[Deleted member 105431]

The magnets on the outside could affect any Hall effect sensors in the boiler.

What Hall effect sensors does this boiler use?

Tony

Flow switch and fan have hall effect sensors

 

[Agile]

Thats what I expected, but they are usually "digital" rather than analogue and have Schmidt triggers built in to give hysteresis.

Its therefore rather odd that something ( else ? ) is apparently so sensitive that it must be an analogue operation. And even give a fault code to the display.

Perhaps there is another Hall effect device?

Perhaps they have built it in to prevent fridge magnets obcsuring their brand name on the casing?

Tony

 

[DP]

Gasinayr4, sorry if I upset you. You must be right in your findings, but the big problem here is that there are no magnets stuck to the case apart from those fitted by the makers. Do you think these should be removed? If that is what needs to be done, then should the makers not be bringing out a mod recall?

There is a relay on the PCB that is sitting in the position that keeps the diverter motor in HW mode. The LED that lights to indicate HW demand is in operation is not ON, neither is there a demand for HW. Clock is calling for CH, which should switch this relay to operate the diverter motor and position the diverter for CH demand. The relay does not operate. Next thing I will be checking is if the relay coil is getting the voltage to operate. Will post findings.

Boiler has worked well for two years. I am not here to proove you wrong or right but here for education that people more knowledgeable than me impart. I regret, based on little knowledge I have aquired working on electromechanical equipment for 23 years and then present for last 20 years, I am inclined to look for a solid clear (hasten to add your finding might well be it but there are no magnets on the case)

Tony, the uniselector is an earlier version. It is known as 25 outlet uniselector. Another type was the 50 outlet motor uni group selector better known as the MUGS. One technician was once heard saying "there are many mugs in Dial House"- he was not talking about motor uniselectors.

 

[shawd]

Used to just change the pcb, have had e168 reversed polarity as well, My cure at the moment is fit new pcb and gas valve solenoid not been back to any with the same fault ,

 

[mattsure]

Old thread I know but might be helpful .I have also had e168 from reverse polarity as shawd above. Strangely would work for hours at a time before e168.