Faulty Worcester Juniour 28i Combi boiler

[Gilgamesh]

Hi all,

I have a Worcester Juniour 28i combi boiler installed & fulled serviced. Problem is the boiler occassionally goes through periods of going into lock-out (Slow flashing LED on front panel). Can go for 6-8 weeks running fine then will play up for 3-4 days. After resetting the lockout boiler will run for 10 minutes and then locks out again. I have removed the front cover and watched the flame during operation. When on heating the flame appears weak at start up and eventualy fades just before going into lock out. When using hot water flame is strong and does not fade at all. If I call for hot water whilst heating is on flame strength increases. When I stop calling for hot water when heating is on flame is weaker than before eventually leading to lockout.
I have downloaded the manuals from Worcester's website and this gives two possible faults....over temperature sensor or gas valve. Good gas pressure, good water pressure,
I have an engineer calling tomorrow but other engineers have failed on previous visits. Any sensible suggestions welcome.

Cheers...............Gilgamesh

 

[Gasguru]

Had a similar problem on a 2 year old junior - although by the time I got involved it would lockout at each attempt to fire - turned out to be the board.

 

[Agile]

I went to one with rather similar sounding symptoms and that was a faulty PCB.

When I enquired it turns out PCB failure is quite a common problem.

Tony

 

[Rob]

had flame rectification problem on this boiler....yep, it was.

 

[Gilgamesh]

Hi Guys,

Thanks for the replys. The engineer turned up and couldn't find the fault so left things as they were. It's working at the moment but we're expecting it to fail again. I've decided (from your advice) to try and source a new / second hand / refurbed PCB and fit it myself as I used to be an electrician in a previous carnation, so hoping it's a simple plug in affair. I've looked at eBay and found a few people offering reconditioned PCB's for £80 ( new from Worcester is over £200).
For ref the part number is 87483004840 for Junior 28i RSF combi(confirmed by Worcester).

Does anyone know of any other way of sourcing this part....??

Cheers........Gilgamesh

 

[pannierstan]

I use parts centre and fitted one before christmas for a similar fault. Cost me £150 approx but that was with discount.

Stan

 

[Gas2Air]

Hmm after fitting the board are you going to check combustion and burner pressure are correct?

 

[HarrogateGas]

Hmm after fitting the board are you going to check combustion and burner pressure are correct?

Wont need to on a junior....the board only opens and closed the gas valve. Its not a premixed burner on the junior. So if it was correct before the new board, it will be correct after. The new board cant alter the combustion on this boiler.

 

[Gas2Air]

Not my point HG but yours taken.

 

[Gilgamesh]

Thanks again chaps,

HG thanks for confirming what I read elsewhere........but G2A could you please expand on your earlier point as I want to get this repair spot on for obvious reasons and not miss anything or not cover all the bases.