helpfull fault worcester 28i juniour

[southcoastboile]

just thought id tell everyone about a fault i came across today, worcester 28 juniour, locks out every time, fan running but aps not making, ordered new aps, went back and fitted, all working fine.

2 days later customer phones, same problem, went back and found fan runs on htg but boiler doesn't fire, when hw demand fan drops in speed and boiler doesn't fire, i thought it was a fault with the fan relay on pcb so ordered new pcb, fitted pcb and still same problem,

tested new aps and found faulty, picked up another new one and replaced, on replacing i found new aps had melted blocking of hole to aps tube so not sensing fan speed, could see no obvious reason for this, flue, flame picture etc were all ok, phoned technical and asked if they had come across this, the guy said straight away, i no exactly what that is, there is an intermitant fault with the pcb causing the fan to cut off before the burner so the flames search for air and go under the combustion chamber side pannels.

so if you ever come across an aps that has signs of heat dammage on this boiler be sure to change pcb and aps, hope this helps someone out so they don't do what i did and loose out on the cost of original aps.

 

[mfgs]

Cheers for the info. Always helpful to hear stories like this.

 

[Billy Bob Bob]

seen this fault on this boiler many times,another thing it can do is go to full rate in ch mode and ignore the hl stat and thermister only stopping when the aps totally melts

 

[Kev the gas]

Had this as well, currently repairing a 24iJunior, cuts out at odd times, eventually found fault to be pcb, when you press the lower left Worcester badge you can get the red neon to light and then go out !

All connections checked and double checked, pcb must have a dry joint somewhere?

Customer is chuffed she has a work around till I get back monday with new pcb.

 

[gasmarc]

I have had this problem also except I replaced the APS and then the PCB a couple of stats etc and then i sussed the plastic connector that joins the 3 pipes together had partially melted. What a result I was well happy sorting that one out LOL