Potterton Netaheat Problems - Spark generator ?

[Phil Young]

Hi,

I'm having problems with my venerable but previously reliable Netaheat MkII 16/22 boiler. Looking through the previous very useful postings it seems as if the Spark Generator is failing, but I thought I'd ask here for confirmation.

The boiler starts up okay from cold, and runs through a few on/off cycles, either via the room stat or it's internal stat, but eventually it won't relight.

When it ends up in this state, the air fan is running, the pressure switch has detected this and the spark unit has 240v across it, but there is no spark clicking away. However, the unit must have produced a spark minutes ago to have lit the boiler previously.

Other than fit a new SG (approx £30 online, so not too bad) is there anything else to check ?

I've tried starting from cold with the gas switched off (to check that the thing will produce multiple sparks), and I've opened up the SG case but there's no obvious signs of component failure. Maybe the capacitors have dried out or something and it fails after being powered for a few minutes ?

Any comments approciated,

Cheers,

Phil Young

[tarquinlinbin]

You need to check visually whether a spark is occuring at all. This may not be completely visible through the viewing window.

As a seasoned gas man I would use a multimeter connected to the gas valve pilot solenoid. I'd then remove the gas,initiate the start up sequence,when the spark gen starts I'd observe the pilot block directly for signs of spark and also check for 240Vac at the pilot solenoid. If there is 240Vac and no ignition,id manually light the pilot with a match to check for gas flow. If it does light,then you need to investigate the spark gen its lead and probe. If it doesnt light,the gas vavle could be duff or there could be a blockage between pilot gas outlet on valve and the pilot burner.

I'm not suggesting you do this yourself as there are dangers for the uninitiated !

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[Phil Young]

Removing, opening and replacing the spark unit seems to have sorted the problem, so maybe it was just a dirty connection somewhere. I can't understand why everything worked okay for a few cycles and then failed though. C'est la vie.