Potterton Netaheat Electronic 16/22

[GeoffreySW]

The boiler has stopped firing up. The programmer, pump and divertor valve are all working. After reading several posts on this site and using the fault finding charts in the manual, I have now hit a brick wall.

The fan is not running - there is mains voltage coming into the PCB but nothing coming out on the fan supply plug T6 & T7. I have checked the APS and although it was operating, decided to change it anyway. Still nothing happening. Decided it could be a fulty PCB, so changed that too - still nothing. Changed the thermostat in case that was faulty - still nothing.
Can anyone confirm the sequence of operations - I am presuming that the thermostat must be switched on to supply power to the PCB which powers the fan which produces the positive pressure in the case to operate the APS which starts the ignition sequence. Is there anything else that can prevent the PCB initially supplying voltage to the fan?

Thanks in advance

GSW

 

[powell30]

Blimey, keep going. You'll have a new boiler by spares soon. Call out someone who knows what their doing. It will be cheaper in the long run

 

[seco services]

Blimey, keep going. You'll have a new boiler by spares soon.

have you checked the internal fuse ?

 

[GeoffreySW]

Fuse is ok - could there be any other reason (apart from the new PCB being faulty) that I would'nt be getting a supply to the fan?

 

[bengasman]

Most importantly, you have opened a positive pressure case with no way of confirming that it is not leaking; you need a RGI to check that. Whilst he is there to check the safe operation, he can solve the problem too. Probably would have been cheaper to have it repaired by a pro, rather than start randomly changing parts.
Might be an idea to have the boiler serviced at the same time, the whole job will be better value for money that way.

 

[powell30]

Are you sure you have a call for heat on the boiler? Check external controls

 

[shambolic]

Has the mercury vapour switch on this (if its the auld one if my memory serves me right) gone back to rest position. Or is thsi the one with the 11(or16) pin plug in relay on the board!
Been that long since Ive worked on one

 

[GeoffreySW]

I've tried ramping up the room stat to max, along with the boiler stat. It still isnt kicking in when both the CH & water switches are on - I had presumed it too coincidental that both systems would fail at the same time.

 

[seco services]

check the sw live to the boiler

 

[GeoffreySW]

On my way home now to check it.

By the way - I am waiting for a boiler specialist to get back to me, but this is the third day he hasnt turned up so I'm having a go myself. I am an engineer with some experience with heating systems - mainly industrial, and I am aware of the potential dangers involved with this model of boiler.

 

[GeoffreySW]

The switched live supply is operating - I am assuming that this is the signal from the programmer that operates when the CH or HW switch is flicked and the appropriate stat is calling for heat?

 

[GeoffreySW]

Have gone back thru the fault finding charts - still no voltage across T6 & T7 for fan, the APS circuit on T5 & T7 is closed thus suggesting control unit?
The thermostat fault finder chart gives voltage to the unit but not a closed circuit across connections 3 & 6 on stat which suggests replace thermostat?
I've replaced both these components and am still getting the same results. I suspected a fault on the fan but have put a seperate feed to it as a test and it is running fine.

Still can't get hold of the 'boiler specialist' - any more ideas out there?? Please??

 

[bengasman]

Maybe try the next boiler specialist in Cheshire?

 

[GeoffreySW]

Helpful - on my third now!

 

[powell30]

I think as this is a positive pressure boiler you should now stop trying and call out someone who knows what they are doing. It will be better in the long run.