Help - Ariston MicroGenus problem !

[arthurpitch]

Hello
Hoping somebody can help, got an Ariston MicroGenus 23 MFFI combi boiler
Every couple of years it's always stopped working if the water pressure fell too low or the boiler was switched off for a few days such as on holiday, and the only thing to make it work again is fit a new air pressure switch which is very easy to do. So this time I again fitted new air pressure switch.
Only this time it's not working properly. If it has not been used for a few hours, and you turn on the hot water, the fans kick in but after about 10 seconds the red ignition failure light comes on. Then if you press the reset switch next to the red light while continuing to keep the hot water tap running, the red light goes off and the gas burners fire up and work, but only for about 5 seconds, then the burners stop and the yellow Fume Sensor light comes on. Keeping the water running the fume sensor light goes off by itself after about 5 seconds, and again the burners fire up and heat the water. This cycle keeps repeating itself, off/on.
One more thing, it seems to need the water replenishing about once a week as the pressure gauge steadily falls by itself.

 

[hanns21]

You have a air flow. Problem and either a leak or a new expansion vessel. Both a cheep repair. Get a gas engineer in instead of messing with things that can become dangerous

 

[arthurpitch]

Thanks m8, I reckon that's good advice that I'll follow

 

[hanns21]

No worries. With your boiler firing off and on the air pressure switch is switchinv off and on. So not enough air for the switch to work. With you having to top up once a week it sounds like a small leak tho i engineer will be able to find the cause easy enough. Hope this helps. Cant give anymore advice as boilers can be dangerous