Ariston microGenus 27MFFI no hot water Intermitent fault

Hi All,

I've spent a good few hours looking through the topics and replies due to the problems i am having with the subject problem.

The boiler is approx 6 years old

Basically, the boiler keeps cutting out when any hot tap is running. This is getting progreesively worse. I use to be able to turn the boiler on and off and then i could run a bath, fill a sink etc.

After advice given to people with similar problems, i removed the secondary heat exchanger, this was very clean, but i still gave it a good blast with the jet washer.

I put back together and it worked fine. I ran a bath, still ok. Came to run a sink full for the pots a few hours later, and the problem reoccured. I then turned the heating on and tried to run the tap again, this time it was hot.

Can anybody please give me some much appreciated advice as to where i could next look at solving this problem.

Don't know if this is anything to do with it, but sometimes especially in winter the 2 red LED's are lit in hte morning when i go to investiagte why the heating hasn't come on at the pre programmed time.

Kind Regards

Anthony

Sounds like an overheat problem, usually caused by a soiled system. These boilers are quite sensitive to that. Alternatively, could be a dodgy pump

main flow/ch thermistor

The PCBs on that model are not very reliable either!

Tony

Hi All,

Thanks for the replies,

I have been on the phone to MTS and explained the problem, the guy said if the fan stops or slows down it is a temperature or circulation problem, if the fan keeps running it's the air pressure switch. I checked and the fan slows down and stops, so i'm going to look at the temprature sensor. Is this also called the thermistor. i cant find thermistor on the drawing only temperature probe. Are these the same thing.

Anybody any other ideas, or who are local to the Chester / North Wales area.

Anthony

The sensor, NTC or temperature probe or anything else you decode to call it might be faulty but its probably more likely to be as a result of dirt in the boiler.

I would identify if that was the cause by monitoring the temperatures within the boiler.

Tony

i think that the minimum burner pressure setting on the gas valve needs resetting.common fault on these boilers.
as we all know do not attempt to do this yourself.