Potterton 80 blowing 2A fuse

[Timbuck]

My Potterton 80 has gone on the blink again..This time its blowing the 2 Amp fuse on the PCB..it appears to blow on the ignition sequence as the Domestic supply is turned on. any ideas on how to test for the fault.

 

[gasandoilman]

what size fuse have you got on your fused switch?
Could it be the fan? at what point does it blow

 

[Timbuck]

what size fuse have you got on your fused switch?
Could it be the fan? at what point does it blow

Hi and thanks for for quick response..The fused mains switch is a 3 amp ...It works just as you'd expect it to, right up to the point where it should ignite and the green light goes on and on the ignition click the 2A blows...The fan sounds as if it works ok.

 

[gas4you]

if its getting as far as ignition then fan will be ok. I would suspect the gas valve solenoid first.

 

[Timbuck]

Just in case it was a solenoid..I swapped boards for a new spare one that I had...but the fault was still the same so I suspect its something not on the main board...I was wondering about the other board at the back with the spark generator gubbins ..Could there be anything that could have shorted out on that....or is the gas solenoid not on the pcb but on the valve.

 

[Rob]

Solenoids are on then gas valve. Use a MM to check resistances. or simply disconnect the gas valve wiring from the board and see if the fuses stop blowing.

 

[ChrisR]

WHat sort of potterton 80?
If a COmbi 80 look at the microswitch on the tap waterflow switch. Could be full of water.

 

[gas4you]

Chris a point for me to learn here, if it was the tap flow switch would it not blow when flow detected rather than when trying to ignite

 

[ChrisR]

Dave of course you're right - I read "as the Domestic supply is turned on" and shot past Timbuck's second post!

Presumably it does it on CH too??

(goes off to see what's on that other board - the "full sequence" one...)

Yep I concur - try disconnecting the connectors on the gas valve (not the board end plug or you'll be disconnecting the overheat stat which would stop things working).
If the fuse doesn't blow, but it goes on to the ignition sparks, you've found it.

 

[Vic Spanner]

Check to see if the air vent as been dripping water onto the gas valve electrical leads.

 

[Agile]

Clever bit of design there!

The AAV leaks as they all do eventually and then drips onto the gas valve and a £20 parts replacement becomes £160 !!!

 

[ChrisR]

£160 !!!

If you want to make some money I suppose.

Or clean them up and dry them out, or change the solenoids...

 

[Timbuck]

Dave of course you're right - I read "as the Domestic supply is turned on" and shot past Timbuck's second post!

Presumably it does it on CH too??

(goes off to see what's on that other board - the "full sequence" one...)

Yep I concur - try disconnecting the connectors on the gas valve (not the board end plug or you'll be disconnecting the overheat stat which would stop things working).
If the fuse doesn't blow, but it goes on to the ignition sparks, you've found it.

Well I disconected the Gas Valve Solenoid..But it blew the fuse again...I've read somewhere on the Forum that a suppressor capacitor on the Spark Generator could cause this but I'm not sure if it was the same model boiler they were talking about.

 

[Vic Spanner]

Disconnect wiring on pump and try.

 

[Timbuck]

Disconnect wiring on pump and try.

Brilliant deduction it was the pump...Hoooray. I didn't check it before cos iwas only using it for domestic supply......It's a Myson Compact CP61..What is the best replacement part if I cant find one like it....And question can I still us the domestic supply with the pump disconnected?.