Ariston MicroGenus 24 HE MFFI - Error A03

[CaptainSideways]

Ariston MicroGenus 24 HE MFFI - Error A03

Heating runs for approximately 5 minutes then errors. On reset, cycle repeats. Error code indicates that returning pump temp is above 103 Degrees.

I replaced the Overheating Thermostat (Ariston Part #996065) but issue persists.

I then switched off the heating and the hot water will run for 5 minutes without error; suggesting that the expansion vessel is okay.

Does this suggest that the pump is degraded / broken?

(I'm no boiler engineer - so the above assumptions I've made might well be wrong!)

 

[hanns21]

It could be a number of things but your going to need a boiler engineer to look at it, does sound like a circulating problem are could be diverter valve stuck in hot water position are faulty ntc! All of which can be tested to see if there working before being replaced

 

[ianmcd]

I then switched off the heating and the hot water will run for 5 minutes without error; suggesting that the expansion vessel is okay.

Read more: //www.diynot.com/forums/plumbing/ariston-microgenus-24-he-mffi-error-a03.397911/#ixzz2xNkrkdcc


The expansion vessel plays no part when running HW.

 

[Charnwood]

Ian, I read the topic you linked to and got a distinct feeling of déjà vu.