Worcester 28i Junior fault (non greenstar)

[R1CKY]

Been out to this boiler today, I've done all the checks and resistances of everything are within limits and everything is pointing towards the PCB and i'm 90% sure its the problem. Just thought I'd check here though as I hate diagnosing PCBs for intermittent faults and I've not come across this before.

Boiler seem to run ok on heating and hot water individually, but as soon as you run the tap whilst the heating is on, the fault LED flashes four times a second. Upon resetting the boiler, it goes through the motions, fan runs, APS makes, then the fan seems to lose power, burner ignites momentarily just as the fault light starts to flash. It will continue to do this unless you leave it be for about 20 minutes.

As I said I'm pretty sure its the PCB, but just thought I'd see if anyone has seen this fault before.

 

[Billy Bob Bob]

sounds like pcb,but have had lots of aps issues on this boiler causing the same symptoms

 

[R1CKY]

Funny you should say that, as that is what I'm thinking it could be also! Fault finding isn't so much fun when its my account the parts are going on!

 

[leethegasman]

same as gas man says i have had this problem on one before and the customer rang me as other GSR engineer had changed pcb,gas valve and they lost confedence in him i striped down give it a good clean and service which increased the fan pressure which in my case held APS open as i suspected it was dropping out does not mean it is not the PCB in your case but i personly would take a pcb and aps with you give it a good clean and service first then poss ring worcester tecnical if needed then start changing parts but if you need to you will have them with you.in my case this was a good 10 months ago and i have done other work for her and she had no problems since then.

 

[R1CKY]

I'll definitely take both, the APS isn't that expensive. Cheers guys!

 

[smhstu]

Take the tubes off the APS and check The nipples on the APS as these often melt as there right near the burner, found this a few times

 

[Billy Bob Bob]

Take the tubes off the APS and check it as these often melt as there right near the burner, found this a few times

sure that was the cause? every junior i have seen with either melted tubes,y piece or aps have been down to a pcb fault

 

[R1CKY]

I didn't take them apart, but gave them a once over and they seemed ok! Customer just phoned and said it isn't working at all now, don't you just love it when that happens! Gas Man, don't know of anywhere in South Wales open on a Sunday to get parts do you?

 

[Billy Bob Bob]

I didn't take them apart, but gave them a once over and they seemed ok! Customer just phoned and said it isn't working at all now, don't you just love it when that happens! Gas Man, don't know of anywhere in South Wales open on a Sunday to get parts do you?

sorry no,i dont have anything in stock for that boiler either or you could borrow them

 

[R1CKY]

Never mind, thanks for the offer though!

 

[Rob Sale]

Sounds like the APS is dropping out, i'd replace that first

 

[arran197]

Had a similar issue, APS was the problem. Changed the board and it didn't work.

 

[R1CKY]

Took a gamble and lost! Replaced the APS and it fired straight away, all seemed well until I put the outer case on 20 minutes later and fault returned! PCB solved it! Win some you lose some!

Thanks for the advice guys!

 

[TBServices]

Pcb common fault on these

 

[R1CKY]

Bugger! Just phoned back and said its flashing again! Going back AGAIN tomorrow. I'm lost, left the new APS in there, fitted new APS hoses, tee piece was ok. Going to take the fan off and check the venturi tomorrow and phone Worcester from site AGAIN!

The expansion vessel has failed on it too, I know it is highly unlikely, but there is no way the two issues could be linked is there?

 

[Billy Bob Bob]

Bugger! Just phoned back and said its flashing again! Going back AGAIN tomorrow. I'm lost, left the new APS in there, fitted new APS hoses, tee piece was ok. Going to take the fan off and check the venturi tomorrow and phone Worcester from site AGAIN!

The expansion vessel has failed on it too, I know it is highly unlikely, but there is no way the two issues could be linked is there?

no there not linked worcester are going to say its the wiring loom

 

[TBServices]

I'd have fitted a new boiler by now lol

 

[R1CKY]

Already suggested it!

 

[southcoastboile]

Double check the new aps doesnt show any signs of being melted if so PCB, also clean up connections to APS if they have gone rusty which seems to happen alot on those

 

[leethegasman]

same as gas man says i have had this problem on one before and the customer rang me as other GSR engineer had changed pcb,gas valve and they lost confedence in him i striped down give it a good clean and service which increased the fan pressure which in my case held APS open as i suspected it was dropping out does not mean it is not the PCB in your case but i personly would take a pcb and aps with you give it a good clean and service first then poss ring worcester tecnical if needed then start changing parts but if you need to you will have them with you.in my case this was a good 10 months ago and i have done other work for her and she had no problems since then.

Strip fan out and clean and Venturi and also make sure no blockage on flue pipe work , also what is length of flue ?

 

[R1CKY]

Going back at 5 this afternoon, will clean the APS connectors as they were rusty. Will strip the fan and clean the venturi. It is a horizontal flue, so hardly any length at all! Turning in to a pig of a job, for a mate of my girlfriend's Father, so not going to make much on it!!

 

[R1CKY]

Relief!!! The flashing that had returned, was the slow flash because of the low system pressure caused by the expansion vessel which I am changing Saturday.

 

[TBServices]

Relief!!! The flashing that had returned, was the slow flash because of the low system pressure caused by the expansion vessel which I am changing Saturday.

Excellent news! I hate these juniors, they were Worcesters first step towards crap boilers.

 

[JJ The Plumber]

Glad you got it sorted

 

[R1CKY]

So am I! When I saw the fault light flashing slowly I was over the moon!

Thanks once again to everyone for the advice and help!