Ariston Combi unidentified problems (Ed.)

[Matty336]

Hi Matt retired gas tech here, battling with my own boiler, requiring some wisdom from those of you familiar with Ariston, and ideally the micro genus 2 mffi 24kw (combi) circa 2007 .

No H/W or C/H. No fault codes. Pump running, no fan or subsequent ignition.

No ext room stat or hive fitted etc. OEM Analogue programmer on control panel. Bog standard.

Call for heat - Pump runs, but fan won't run, and subsequently no gas / ignition sequence. But when I switch off C\H constant to off position on programmer, fan runs momentarily, sometimes 30secs, sometimes 90+secs intermittently. When the fan runs, it's sent a healthy 240v feed @ 4amps from PCB.

I've checked continuity, voltage and amperage of entire wiring loom from fan leads back to PCB - all ok

Only when the heating is switched off, and fan overrun kicks in that power is sent from PCB. No power from PCB to fan when there is call from programmer and/or running tap (Pump does run when call for heat from H/W and C/H).

Seems C/H and H/W flow sensor works along with diverter and O/H stat, or I'd be seeing fault codes.

I've proven the fan works by rigging a separate 240v feed from socket directly on to fan, to check fan operates all ok.

I had the fan, pump, pressure guage and O/H stat go on me earlier in the year. Then most recently, PCB pooped itself.

I replaced PCB with reconditioned unit from boiler spares company. The first they sent was faulty, riddled with so many faults it was laughable, and so they sent me another, which is the existing one now fitted to my white rectangular money pit attached to my wall.

My gut feeling tells me the boiler spares company has sent me another dodgy board and it's the PCB giving me the run around again???

Anyone have any answers? Some help would be massively appreciated!

I've spoken to Ariston and a bunch of plumber / gas mates and they are baffled, not provided me with any answers really, just the same old response - "F-it off and get yourself a new boiler mate" is the general consensus. But not keen to spend £1000 and all the faf, when I can sort this for a fraction.

Unfortunately the Ariston tech dept, with all their combined knowledge at the tech desk is of recent boilers, not twenty year old combi boilers... Somebody please be a legend and saviour and help a guy out!!!

 

[RandomGrinch]

. When the fan runs, it's sent a healthy 240v feed @ 4amps from PCB.

Not that I know anything, or that we are able to talk about DIY gas work on the open forum.
But I believe the Ariston fan is rated @55W....

That would be a current draw of only 0.24A.

 

[Matty336]

Apologies, I meant 0.4amps. 0.24 you say, I'll check that out, nice one

Didn't realise we couldn't talk gas on here. My first time, soz. I am ACS gas safe qualified/registered. Just inactive.

 

[RandomGrinch]

Didn't realise we couldn't talk gas on here. My first time, soz. I am ACS gas safe qualified/registered. Just inactive.

You should be able to register with the "Combustion Chamber" - that's where the RGI's hang out!

https://www.diynot.com/diy/form/combustion-chamber-registration.1/select

Apologies, I meant 0.4amps. 0.24 you say, I'll check that out, nice one

If it is 0.4A, and the fan rating is 55W, there could be a shorted winding on the fan?
Maybe enough to overload something on the PCB, but I'm not at all certain.

 

[Matty336]

Fan already proven to operate without fault, just not when I want it to. Just seems something else at fault in the sequence of operations prior to fan running.

Thanks for the combustion chamber info. I have just registered with Combustion chamber - how do I actually access it?

 

[kidgreen61]

Bin it, the software in those things is hideous when it hits self destruct mode.

 

[Matty336]

When you say software, you refer to PCB and it's coding? Would a brand new PCB (not a refurbed board) be the answer then?

My gut feeling tells me it's these shoddy refurbished boards giving me the run around.