Ariston LPG combi working but not starting. Help!

[davidwatts]

Help needed please with an Ariston Dia 20 MFFI CE combi, around 10 years old.

The boiler was refusing to fire up at all. Called out an engineer, who checked it over and diagnosed a gas supply problem at the LPG tank - a faulty UPSO/OPSO valve. Spoke to the gas company who own and maintain the tank, and they said it probably wasn't faulty and talked me through resetting the regulator, which had tripped. Boiler fired up first time after the reset, and ran fine for a few days.

The boiler actually operates normally when running. However it is incredibly reluctant to start from cold, either CH or DHW. The fan comes on as normal but there is no igniting of the burners and the red lock-out light comes on. It usually sparks, but occasionally there are no sparks for a while. It may fire up after repeated pressing of the red light (20 times or more), but sometimes it won't fire up at all.

I'm curious as to whether the non-starting is still a gas supply problem (ie. a faulty valve like the engineer said), or if it is an unrelated ignition problem. And if the latter, why is the boiler so reluctant to fire up initially when it is happy to do so once up and running?

All help gratefully received. Many thanks.

 

[gas4you]

If there is no sparking then I would suspect the aps is not proving the fan is running.

If there is sparking then I would suspect a no gas fault. Could be upso or could be fault on gas valve.

Have you any other gas appliance that are working?

You need an engineer back to diagnose.

 

[davidwatts]

Thank you for your advice. I don't have any other gas appliances sorry. Tonight the boiler fired up after three presses of the red light, then stopped and restarted itself continually for about five minutes [CH mode] before I switched it off. I waited twenty minutes and tried again, and it was fine after that. Arrrgh!

Would a faulty UPSO cause a boiler to behave like this? Or is it ageing boiler syndrome, where components like the aps/gas valve become inefficient and no longer do their job properly? The gas company will charge me a lot to come out and inspect the UPSO, and I can't spare that sort of money on the off-chance it will solve the problem.