i hate intermittant boiler faults.

[obseen16]

hi guys, went to have a look at a worcester 24i junior today, it locks out every now and then. could i get it to play up tho. not a chance, the only thing i did notice was that at one point the spark electrodes kept on cycling even though the burner was lit, it locked out once while i was there, i think that the flame sensing electrode was at fault here, i gave it a quick clean and checked how far it was sat off the burner and all worked well. however as this is an intermittant thing could it be someting else,

the reason I think it was the flame sensing electrode was because on the only time it locked out the ignition sequence went as it should but once the burner was lit the spark electrodes kicked in again paused and then again then went to lock out even though the burner was lit the whole time.

what do you guys reckon?

 

[Billy Bob Bob]

if you have proved continuity on the detection lead and electrode it can only be one thing the pcb

 

[Rodreguez]

with gas man on this 1

 

[ghost]

I have never worked on that boiler, but I really would try an ionisation probe (flame sensing electrode) first before trying the pcb. It's the cheaper of the two. If it still gives the same fault, then look deeper. What you are describing sounds to me like the pcb is losing the current flow from the ionisation probe, it thinks the burner has gone out, so it trys to fire up again until it locks out.

 

[obseen16]

I have never worked on that boiler, but I really would try an ionisation probe (flame sensing electrode) first before trying the pcb. It's the cheaper of the two. If it still gives the same fault, then look deeper. What you are describing sounds to me like the pcb is losing the current flow from the ionisation probe, it thinks the burner has gone out, so it trys to fire up again until it locks out.

yes exactly, thats what my theory was. since posting this though the boiler has been fine. maybe it was just some crud on the probe that was stopping/weakening the signal. just a weird one when you cant get the damn thing to lock out while your there.

 

[obseen16]

hi guys, just a quick update to this post, im now really confused by this one now, the flame sensing probe has continuity. i went back to the boiler the other day, it is now locking out at least once a day sometimes more. it is bringing up 2 different fault codes now aswell,

i followed the fault finding procedure and the MI is indicating that it is either PCB, blocked pump, air pressure switch, so i called worcester technical and they advised me that its either the gas valve or the flow switch, so i am now totally confused and really dont wanna start throwing parts at it. i linked the flow switch to seee if that worked but it didnt, can anyone help me with this one?

 

[diesel_ltd]

are you getting the correct voltage at the fan?

 

[wards]

had similar fault on a glowworm some time back,cust had engineers out and they could not find the cause,turned out that the burner gasket was damaged,replaced it and no call backs,just a thought.HTH

 

[obseen16]

are you getting the correct voltage at the fan?

Yes mate voltage at the fan is fine on high and low,

 

[gasmarc]

i had one of these the other week ,it worked for ten minutes then kept locking out it wasnt even sparking or fan going on full speed but would go to full speed if put on heating for a few seconds ,it was a pain in the neck and i ended up walking away from it as it was pointing to a pcb or wiring loom issue, I spoke to a mate whose job it was and he said it was a pcb fault which i had put it down to

 

[obseen16]

yeah i put it down to pcb on this one. but the customers said the boiler has amazingly started working properly again. i know it wont last long but im hoping in a way that they will get someone else in to sort it when it cocks up next week. wish i could have walked away from it straight away.

it probably is the pcb board, but i always have a slight doubt when changing them as they cost alot if your wrong, and you cant return them either.

 

[gasmarc]

yes i make you right on that one ,we only know so much and sometimes its not enough, i hate those days

 

[aggis]

Checking for continuety on electrode & leads doesn't mean they're ok, hairline crack in electrode won't show.
Always best to change ignition & detection probes, if still sparking after ignition.
Very frustrating when boiler keeps showing diff error codes, sometimes you've got repair one thing at a time & what you know. Pcb last port of call.

 

[gasmarc]

hair line cracks on electrodes are far and few between which i have never seen or come across in 15/20 years ,but i dont dispute what your saying

 

[craig49]

hi there was wondering if anyone could recommend any courses on boiler servicing,maintanence and repair? I am gsr and want to start moving away from installation. any advice would be most apreciated!

 

[dontknowitall]

I think Worcester does.

 

[g-man]

I did some fault finding/Combi courses at Baxi - Pretty good.

 

[combo]

Can't you test in real time back at the PCB, on the ionisation circuit terminals ?? obviously you will have to wait for the fault to appear but it will tell you exactly what the pcb is 'seeing' at the time of fault. Iwould imagine you'd be better/easier reading voltage as opposed to in-series current.

 

[Dotty]

Ancient thread revival moved.......