Ariston Microcombi boiler problem (A23/MFFI)

[ailbeb]

Hi, I have a fault with my Ariston A23/MFFI Microcombi.

I've had to replace a faulty Air Pressure Switch 3 weeks ago. Since then a different fault has developed where the boiler switches on but trips out after 2/3 seconds, then restarts and trips out again after 2/3 seconds. This goes on as long as the boiler is switched on.

The boiler is heating the radiators and the water but i need to solve this constant switching on/off problem.

The PCB has been checked by a pro and is working ok, but they haven't ben able to diagnose the problem.

The boiler is less than 2 years old but out of guarantee.

Any suggestions welcome!

Thanks.

 

[gas4you]

Hi, I have a fault with my Ariston A23/MFFI Microcombi.

I've had to replace a faulty Air Pressure Switch 3 weeks ago. Since then a different fault has developed where the boiler switches on but trips out after 2/3 seconds, then restarts and trips out again after 2/3 seconds. This goes on as long as the boiler is switched on.

The boiler is heating the radiators and the water but i need to solve this constant switching on/off problem.

The PCB has been checked by a pro and is working ok, but they haven't ben able to diagnose the problem.

The boiler is less than 2 years old but out of guarantee.

Any suggestions welcome!

Thanks.

Check air pressure pipes between fan and air pressure switch. Check pipes are connected the correct way round. Check there are no splits in pipes. Check venturi in fan is clean. Does boiler fire ok with cover off if so re-check the above

 

[ChrisR]

Flue faults, like coming apart inside, will also cause this.

 

[ailbeb]

Will check that out..

Thanks for the swift reply!