Problems with an Ariston A23 Eurocombi - Possible Ignition Problem

[E Parton]

Hi
I wonder if someone would kindly advise me so that I can pass any help on to the Heating engineer currently working on my combi boiler.
As mentioned it is an Ariston A23 combi ..which has run flawlessly since it was installed almost 10 years ago ..
During the very cold weeks over the holidays ...the red warning light above the ignition switch came on and the boiler tripped out ...
No HW was being drawn at the time ...but was running CH ..
Since then ...the boiler has been restarted a few times ..and almost always fires up first time ...from cold.
The boiler never appears to cut out during its initial burn ..but more often than not cuts out immediately following the second time the burners fires up fully.
This happens in both CH and HW modes ..
I checked water pressure ..and made sure no air was trapped in the rads ..
..I then decided it was time to call in a heating engineer ..
He has since made 2 visits ...but I'm still sat in the cold and without hot water ..as the boiler will only remain running for about 2 -3 minutes..
The overheat light never comes on ..only the red led above the ignition button..
The Engineer has replaced the flame sensor probe ..and the spark electrodes ...and is currently ordering a spark generator module ..
Both the left and right control boards have been visually inspected for dry joints etc ..but nothing apparent..
I'm worried as this fault appears to have him at a loss ..and that part exchanging as a method of fault finding could prove very expensive ..unless you guys can narrow down the field as it where ..
there is sometimes a buzzing noise accompanying and just preceeding the shutdown ..
Any info you provide will be passed on to the engineer on his next visit ...but I do understand the basic principles of operation ..so I can pass on any useful info correctly.

Can anyone please help me ..??
I would like to get my Ariston back in service again ...as its been so reliable for a number of years ..
rgds
Evan

 

[Puddle]

Ariston get some bad press,they made a mistake with design fault with spark electrode damaging pcb on the newer models and cost of pcb but the one you have was a good boiler ,it is getting on now however still about

As for the buzzing,this is probably the solenoid on the gas valve,had a few on this boiler,if happening just before shut down/lock out,indicates maybe gas valve sticking,not opening thus lock out,new valve required however would say you my have come to the cross roads,it has done well maybe time to replace,putting money for repair to replacement otherwise you may find after a few years you have spent a lot in repairs and left with old boiler that on top of what you have spent,dies completely and has to be replaced anyway
imho

 

[maul]

buzzing noise is possibly the gas solenoid valve or one of the relays on the board it has several, but to confirm it you would have to listen carefully to where the buzzing is actually comming from.
10 years of switching takes it toll on a relay
check the connections to the gas valve from the board
also check the air pressure switch at the top left of the case

 

[E Parton]

Many thanks for your reply Puddle ...
You may well be right about the Ariston nearing the end of its useful life ...but it doesn't get the hammering that it would might have got ..if I didn't live alone .
I'll pass on your advice to the engineer ...as the gas valve was on next on his hit list .
If I can get it fixed up at reasonable cost ..it will buy me some time to get saving for a new boiler..
Like everone else I suspect ..money is a bit tight at the moment ...so some breathing space whilst I fill the piggy bank wil help.
I do appreciate your help.
rgds
Evan

 

[E Parton]

buzzing noise is possibly the gas solenoid valve or one of the relays on the board it has several, but to confirm it you would have to listen carefully to where the buzzing is actually comming from.
10 years of switching takes it toll on a relay
check the connections to the gas valve from the board
also check the air pressure switch at the top left of the case

..again ...
my grateful thanks Maul ..
I'll print any replies off ..and pass them on to the engineer who hopefully will be back tomorrow..
I can pick up a 2nd hand pcb on ebay ...so again ...this might be a way to buy some time whilst I save for a new boiler.
rgds
Evan

 

[E Parton]

..back again with another question ..
At the moment it is looking very much like the gas valve/solenoid assembly.
But it would appear there are at least 2 types fitted in the A23..
Mine appears to be a SIT TANDEM valve part number 570732
but there is also the SIT SIGMA valve assembly ..part number 574232.
I suspect one has superceeded the other..?
My question is ..
can the Tandem valve(mine) be replaced with the Sigma version ..
The reason I ask is that I think I can obtain a new Sigma valve for under £80 ..
..whereas a new Tandem valve ..if its even still available would be at least £60 more expensive ..
Can any expert advise..
My Heating engineer doesn't return until monday ..(another weekend in the cold) ...but I would like to have the answer ready for him when he next calls.
rgds
Evan

 

[Billy Bob Bob]

post a picture up of you old one is it the twin solenoid type? tandem and sigma valves very different

 

[E Parton]

Thanks for a quick reply Gas man ..
The valve is still in the boiler at the moment ..but I'll dig out my camera and try and get a decent snap to upload asap..
rgds
Evan

 

[E Parton]

A quick snap of the valve added above ..
hope its clear enough..
rgds
Evan

...and close examination reveals 2 x solenoid coils ..
..not apparent in the picture..

 

[Billy Bob Bob]

thats a sit tandem if you are buying it try abkot uk

 

[E Parton]

..Thanks Gas Man ...I suspected it was a Tandem ..
I take it then that the Sigma wasn't a part which directly replaced the Tandem in later models ..?
..and thanks for the link ..I'll take a look..
rgds
Evan

 

[Billy Bob Bob]

i think the sigma was used later down the line,most are tandems though,i take it your engineer has checked gas pressures are correct?can cause same fault

 

[Billy Bob Bob]

just reading this again,looks more like a detection fault IMHO,think i would carry out a continuity test on dtection lead and electrode then i would replace the rh ignition pcb,common for the solenoids to make a buzzing noise,sometimes tightening the center screw is all thats required has the engineer verified full burner cross lighting taking place? if it is and gas pressures correct back to detection issues

 

[E Parton]

Thanks for the extra info Gas Man ..
The engineer has so far checked wiring continuity ..
Replaced Flame detect sensor ..
also replaced Spark electrodes
Checked gas pressure etc ...
We both came to the conclusion the fault might lie in detectection ..and that the problem is now ..either the gas valve solenoid sticking ...or possibly the right hand control board ...(possibly relays)
I suspect...its a nasty sort of fault that can only realy be cured by part substitution until the fault is finaly pinned down

 

[Billy Bob Bob]

i suspect it will be the RH ignition pcb,good luck post back when you resolve it,as already said by puddle this is one of the good aristons

 

[E Parton]

Just bought a right hand ignition control board (used but working) ..looks to have had 2 of the relays replaced ??
..maybe a refurbed board ..
£20 including postage ...so hopefully this will eliminate another possibility ..before replacing the 'dreaded expensive' gas valve..
Will report back with any updates..
rgds 2 all
Evan

 

[E Parton]

My gratedul thanks to everyone who offered help with this problem...
Looks like Gas Man nailed it ..
My heating engineer returned today with a replacement for the spark generator and the temperature sensor which is clamped onto a pipe inside the boiler .
He first replaced this but the problem remained though the boiler ran a little longer before tripping..
Since the original device read low resistance I was happy to leave the new one in ..
He was about to replace the spark generator module when I produced the refurbed high voltage flame control board I'd bought off ebay ..
Suggesting he try this first as the spark generator module could always be returned unused as it hadn't been removed from the packaging.
After fitting the right hand board ..the boiler was fired up and we held our breath and waited ..
The upshot is that the boiler has been running for some hours now ...and I've had my first bath for 2 weeks ...
..no I wasn't stinking...I have an electric shower ...but its just not the same
Looks like job done ...
He's going to ring me later in the week to confirm its all still ok ...
,,but looks promising..
rgds 2 all

Evan