Ariston MicroGenus MFFI fault code A91

[handyandypt]

Hi Guys.
I am running a rental using the Ariston boiler as in the title.
I get the punter texting a picture of A91 and no hot water - major panic!!
Luckily I have spare parts for the model and I first swopped the the PCB. No change to fault - ARGGGG.
Next move, check out fan and pressure sensor - all appeared normal - the fan rotated - the pressure switch passed short circuit test.
I replaced both components - the fan and the pressure switch (top of the box dude) and all sprung back to normal function - praise the lord!!
I don't know exactly the faulty bit (punters in - not going to play yet) but investigating the A91 fault on google gave me nothing........

 

[Deleted member 221031]

Ok......

 

[handyandypt]

Update. Fault is actually caused by failure of the hall sensor which hangs off the end of the fan which extracts exhaust (or sucks in air) for the balanced flue system. Ariston part number 65100561. Best of luck with this model as produced 2007 and most are probably scrapped.
P.S. nwgs why "Ok..." - not informative..........

 

[ianmcd]

for the balanced flue system

Doesnt have a balanced flue it has a fanned flue, not the same thing

 

[handyandypt]

The micro genus can be either. Mine has a coaxial pipe making it a Balanced Flue.

 

[ianmcd]

The micro genus can be either. Mine has a coaxial pipe making it a Balanced Flue.

If it is a balanced flue why does it have a fan then ? makes it fanned flue, a balanced flue is a completely different thing

 

[handyandypt]

It's balanced flue, fan assisted. This is for efficiency where you don't take the oxygen from a bathroom to run the system.

 

[ianmcd]

It's balanced flue, fan assisted. This is for efficiency where you don't take the oxygen from a bathroom to run the system.

You have absolutely no clue what you are talking about

 

[Deleted member 267285]

I thought sometimes that the manufacturer incorporates letters into the product description/code, eg mffi I take to mean fan flued? A BF balanced flue? Or am I wrong?

 

[handyandypt]

I will have no more to contribute to this ridiculous subject. My post was to help anyone with this fault code not to become embroiled in semantics.

 

[Deleted member 267285]

I will have no more to contribute to this ridiculous subject. My post was to help anyone with this fault code not to become embroiled in semantics.

Ok, but you need to be clearer on the subject matter first before asking about it, otherwise it benefits nobody in future. @ianmcd knows what he’s talking about, a whole lot more than I do.

 

[handyandypt]

What are talking about? I entered a fault and repair post. Are there people just cruising to pick fault! Have a great weekend

 

[Nige F]

Hi Guys.
I am running a rental
...

good job you're in Portugal not here

 

[handyandypt]

Best of luck with the lockdown dude
Like your upsidedown emoji

 

[ianmcd]

No sorry you thought you would be a smart ass and come on here and tell everyone how great you are, what you did was replace a pcb without the correct equipment to test if what you had done was safe, you replaced a critical safety device, again Illegal for you to do that, you talk about short circuit ? an APS can not go short circuit, you talk about flue systems which you have absolutely no knowledge of, but hey Dude you are just trying to help out , stick to what you actually have knowledge of, because it is not the boiler that you are putting peoples lives at risk with