Ariston Microgenus II 24 - No hot water

[ScottieN]

Hello,

My first post and sorry it's quite long but....

I have been scanning the web to try to find the answer to the no hot water problem with my sister's boiler.

These forums seem to have a lot of answers but most relate to a diverter valve problem, which I'm not convinced is where I need to be looking.

The boiler is a 10 year old Ariston microgenus ii 24. The problem is that there is no hot water.

The rads work fine. When I turn on the hot tap the LED comes on atop the Hot water flow sensor. The motor (I suppose) above the divertor does not move and the boiler does not fire up.

She has bought a replacement PCB on the advise of someone else which I have fitted. The problem remains.

The DHW sensor (small plastic bit with red led) was a bit gunged up from an old leak. I tried to clean the contacts to see if it helped. No joy.

Does anyone know what voltage I could expect to see on which cable from this sensor if it is working?? (red white and pink cables)

Much thanks for any advise.

Scott

 

[Madrab]

Any error code flash up?

 

[Dan Robinson]

I'm interested to know why you are not convinced it is the diverter valve?

 

[ScottieN]

Madrab

No error codes. Display just shows on when in summer mode and the heating temp when in winter mode. All normal as far as I can tell.

Dan

Not sure really. Think I was just hoping that the rather gammy looking DHW flow sensor was the easy option. If I could eliminate this I could then look at the more difficult to reach diverter.

How can I check out the diverter. The motor on top spins up when the boiler is first switched on.

Thanks for the quick replies. Nothing good on the telly??

Ta much

Scott

 

[ScottieN]

So just in case it's useful to anyone else,

The DHW flow sensor switches the pink and white wires.

Bridging the pink and white wires together on the board with a small wire, I was able to fire up the hot water.

So not the diverter valve nor the board have a problem. Ordered a new flow switch and I will see what happens.

Scott

 

[Agile]

Would it not have been quicker and perhaps cheaper to have called an engineer to do the repair?

Tony

 

[ScottieN]

Well only if you take the chance on an "Engineer".

The chap that my sister called was the plumber that fitted the boiler 10 years ago and has serviced it each year since.

£150 for the part he recommended plus the attendance fee plus the fact that he wasn't interested in actually fitting the board left me a bit sceptical about calling another professional.

Anyhow the £15 DHF flow sensor that I fitted tonight has fixed the problem. (10 mins max)

I have put the original PCB board back in and the new one is now on EBAY.

How can I tell the cowboys from the engineers in the future. Obviously some engineers on here. What accreditation should I be looking for.

Scott

 

[Dan Robinson]

Well, if they're over a certain age, and still fitting Ariston, that is a pretty big clue.