Potterton Profile 60E not firing up.

[Uncle Buck]

Can somebody help with this fault please.
The scenario is that the igniter sparks happily but there is no pilot gas supply. I have checked all the obvious things: gas supply is there, overheat re-set has not been activated, there is 240v between T2 & T3 (black & blue wires) to gas valve once stat. and pressure switch kicks in. The pilot jet is clear and the fault finding flow chart says check Solenoid GV1 next. How can this be done? Should I take the front off the gas valve?
There is a plastic connector box held by Torx screws, which connects the two gas valves. There is a small PCB in this and when I put a meter across the pins for GV1 the voltage fluctuates from 0 to 15vac as the igniter fires. This might be because the circuit is not loaded correctly, not sure on this one.
I think I need a Corgi guy to look at this further, but would like to know what others think, in case it is a simple part replacement.
Thanks
Uncle Buck

 

[gas4you]

Gas valve needs replacing. I think you have diagnosed this pretty well yourself.

As you suggest, get CORGI in and don't try to dismantle solenoid/valve your self

 

[meldrew's_mate]

Sounds like you're describing the White-Rogers valve, if you really want to confirm it has failed turn off the gas, take the black connector block off, and measure the resistance directly across each of the solenoids, a reading of a few kohm is normal, the pilot one will show >1 Mohm if it's failed.

Don't turn the gas back on, that would be illegal (but then you've already had the case off to check the pilot!), leave the rest to the CORGI.

 

[Uncle Buck]

Sounds like you're describing the White-Rogers valve, if you really want to confirm it has failed turn off the gas, take the black connector block off, and measure the resistance directly across each of the solenoids, a reading of a few kohm is normal, the pilot one will show >1 Mohm if it's failed.

Don't turn the gas back on, that would be illegal (but then you've already had the case off to check the pilot!), leave the rest to the CORGI.

Thanks for info Meldrew's_Mate. I appreciate what you say about gas safety. Getting 4.9Kohms on pilot solenoid and 1.45Mohm on main solenoid. Could this be the fault?

 

[namsag]

If it is the honeywell gas valve it will say on it somewhere... The solenoids are both the same and the chances of both being shot is remote so swap them over to test and the pilot should light but not main burner, If this works just change the bust solenoid at about fifteen quid as opposed to whole valve

 

[Uncle Buck]

If it is the honeywell gas valve it will say on it somewhere... The solenoids are both the same and the chances of both being shot is remote so swap them over to test and the pilot should light but not main burner, If this works just change the bust solenoid at about fifteen quid as opposed to whole valve

It is definitely a White Rodgers valve and it looks like the solenoids are mounted from inside the valve body and are different sizes. Maybe the Honeywell valve was a later type which allowed for replacement of solenoids without stripping the valve. Maybe the W/R gas valve solenoids are not available as a separate part, anybody know?
To be honest I could turn the bent ends of the solenoid outer case and take of the end plate and slide the coil out, without touching the gas valve. But I would have to have it re-wound, or replace it somehow.

 

[Agile]

. Getting 4.9Kohms on pilot solenoid and 1.45Mohm on main solenoid. Could this be the fault?

Well you have been told to expect 2-4k on each solenoid. Obviously one of the solenoids is open circuit.

However the symptoms indicate a lack of pilot gas.

Are you sure you have not muddled up the two?

Looking at the boiler is the failed solenoid on the left or right?

Many people would take the view that if you can change the solenoids safely you dont need a CORGi if its your own home.

However getting a replacement is not so easy!

Tony

 

[Uncle Buck]

The solenoid I suspect is the small one on the right which is reading 4.9Kohms and the bigger one on the left is reading >1.45Mohms. This does not make sense as it would indicate the faulty one to be the left hand solenoid. Unless one is pulling down the other, when in operation? What circuitry is in the black connector box?

 

[ChrisR]

Rectifier diodes iirc.
I remember on the last one I had, it was the solenoid I didn't think it could be!
As far as I know the solenoid is only available as spare for a different boiler, so I don't think I should be advising you to do that in case it has changed. We have new ones to compare with!

 

[Uncle Buck]

Thanks to all who replied with advice for my problem.

The only reason I needed a minimum cost fix, is that I am replacing the boiler this year and hoped it would last a few more months and not because I'm a tight wad. I could not justify changing the gas valve assembly, just to put it in the skip after a couple of months. Sod's law decreed that it would fall over when it did. Just a shame it was not a Honeywell valve.

There is a diode IC and capacitor in the connector box, which could also be at fault. But it does not get away from the fact that the main gas solenoid coil is reading >4.5Mohms.

I'm having a Worcester-Bosch Greenstar 18Ri fitted in a couple of weeks, so will have to wear my thermals till then.

Thanks again to all. This forum is excellent.
UB