Ariston Micro Combi

[willing2learn]

Hi peeps.

Went to a customers house to diagnose a boiler fault. The above boiler isn't firing, there's no room stat. Tried running the hot tap. Tried re-setting it. Not even the pump is firing. There IS power to the boiler.

I've had a look at the ariston fault finding flow chart. It's looking like a new pcb will be needed. Is there anything else I could've missed before ordering a pcb? My friend who is GSR will be fitting it as I'm not registered until next month.

thanks in advance.

Dom.

 

[Billy Bob Bob]

before looking at a pcb check the basics you dont say if you have checked fast fuses or the lwp

 

[willing2learn]

Hi, I visually checked the fuses, couldn't see any signs of burning out.

 

[gbgas001]

the ariston pressure switch is set to 1 bar... make sure the pressure is 1.5 bar.... check if power is getting to the fan, may be the fans knacked too, did you hear the pump if not the sounds like fast blow fuse as gasman said or PCB.

 

[willing2learn]

Hi Yes, I checked the pressure as he mentioned in the past it has tripped out. It was over 1.5 bar. Are the fast blow fuses pcb specific?

 

[Billy Bob Bob]

the ariston pressure switch is set to 1 bar... make sure the pressure is 1.5 bar.... check if power is getting to the fan, may be the fans knacked too, did you hear the pump if not the sounds like fast blow fuse as gasman said or PCB.

also you need to bear in mind the lwp(low water pressure switch) may be knackered,its a 2 wire circuit loop them together to verify but do not under any circumstances forget to unloop them and leave the boiler working like this

 

[willing2learn]

Just a quick update. Turns out it was the LWP switch, so I'll be picking one up tomorrow and getting it fitted. Thanks everyone for your helpful replies

 

[Billy Bob Bob]

Just a quick update. Turns out it was the LWP switch, so I'll be picking one up tomorrow and getting it fitted. Thanks everyone for your helpful replies

so you have learned.......loads always check the basics glad its sorted mate

 

[willing2learn]

Hi, forgot to update this, ordered a new switch, drained boiler, replaced switch and filled boiler then turned it all on, still not firing. So thought I'd just try bridging the switch again, and boiler fired straight away. Surely I havn't got a new faulty switch. I was wondering if there could be some sludge/dirt in the pocket the switch sits in? Maybe worth flushing through? Or have I missed something glaringly obvious?

 

[Billy Bob Bob]

could be sludge what are you pressuring to?

 

[willing2learn]

could be sludge what are you pressuring to?

Tried it upto 2.5 bar

 

[Billy Bob Bob]

try taking out and cleaning also check where it screws in for a blockage

 

[aggis]

If the lwp has 3 electrical connectors, are the wires connected to the correct terminals ?

 

[gasmarc]

yes good point Aggis

 

[Billy Bob Bob]

i believe its 2 wire

 

[willing2learn]

If the lwp has 3 electrical connectors, are the wires connected to the correct terminals ?

Hi, it has 2, and yes I marked both of them before I disconnected the old one.

 

[Billy Bob Bob]

and you have probably tried swapping them around ?

 

[gasmarc]

it would not make any difference as it just makes once the pump comes on, you will probably find there is dirt in it again, bad design really that a match head of crud can stop a boiler but that what keeps us in business and drives us round the bend sometimes lol

 

[willing2learn]

and you have probably tried swapping them around ?

Yes, will go and give it a clean tomorrow. It's a secondary boiler in a loft conversion, so they're still nice and warm as they have a different boiler running the rest of the house.

Cheers for replies guys.

 

[Billy Bob Bob]

it would not make any difference as it just makes once the pump comes on, you will probably find there is dirt in it again, bad design really that a match head of crud can stop a boiler but that what keeps us in business and drives us round the bend sometimes lol

your thinking of the microgenus this has a pump pressure switch,no lwp the microcombis different twinpass heat exchanger and it has a lwp but no pump pressure switch ,but as i posted earlier i agree on crud back in the lwp,or were it screws in to the flow pipe

 

[gasmarc]

my mistake ,yes like the puma i suppose ,i will get the hang of these boilers someday lol

 

[Billy Bob Bob]

trouble is theres so many of them LOL

 

[gasmarc]

yes I make you right there and i forget whats what and should keep notes which i may start doing soon , for example I went to change a fan on a keston c55 that cost loads ,only to think yes chop the wires of and remove fan fortunately I sussed they supply an extra wiring loom that extends and connects on the existing wiring loom if that makes sense, it would have been a nightmare if i had chopped the wires out

 

[willing2learn]

Update - Gave the prv area where the lwp sits a flush and clean out. All working fine. Thanks to all for the advice on this thread. I'm thinking about getting myself a little netbook and dongle so I can go straight online to download any boiler instructions I might need when working in the future.