Worcester 28i junior only fires up with the cover off.

[Nas]

Does anyone have any experience of this boiler its the non condensing version. The boiler wasn't firing up so I took the cover off to check the APS and everything started working. I put the cover back on and it stopped workign again.

The flue seems to be ok as does the fan, what causes this failure? not much experience with WB so any help would be appreciated.

 

[SimonJohns]

Venturis are faulty. Try cleaning them. If not I think you can replace them

 

[Puddle]

points to a classic flue problem,check all flue ways clear,,along with venturies could be dodgy aps or fan unit

imho

 

[desrob]

venturi as the man said,red .

 

[newgas]

Try to post back and conclude the post, as it will help others with same problem.

(Plus I hate it when posters just ask for help and do'nt bother replying back)

 

[Nas]

I cleared the venturis and the boiler worked ok for a day. Now It has the same problem again. The APS has been changed and is definitely ok. SO are the temp sensor as ive checked the reistances. That only leaves the fan and the PCB.
I've checked the coil resistance of the fan and that also seems ok. I dont really know how to check the PCB any ideas?

 

[SimonJohns]

Have you checked if the venturis are doing their job

 

[Nas]

The venturis are clear and seems ok I can feel the air coming from them

 

[SimonJohns]

The venturis are clear and seems ok I can feel the air coming from them

Ok. But
Have you proved their working with a multimeter on the aps
Have you proved the aps

A pcb is a big ask and not always the answer

In my book you have to prove something before you can do something

 

[Nas]

The fan doesnt kick in when it doesnt fire up. When the fan kicks in the aps works and everything works fine. Thats
Why I'm saying it could be the PCB. Like you I'm hesistant in replacing the PCB without definite proof.

 

[Nas]

Just noticed looking at the manual the -ve tube going to the APS wasn't connected as it was shown on page 23 of the manual. Does anyone know if the white tube should be connected to the T-piece and the sampling point?

 

[Nas]

Just to conclude this post it was finally fixed with a new APS and a new PCB

 

[sparra1100]

sounded like a air problem to me ,so why you needed a pcb am at a loss to work out

 

[Nas]

sounded like a air problem to me ,so why you needed a pcb am at a loss to work out

That was my initial assessment as well. After a while it stopped firing up even with the Cover off. The problem was intermittent initially, the fact it fired up with the cover off ended being a red herring in the end.