Worcester bosch heatslave blowing 5 amp plug fuse

[ianB59]

My 25 year old worcester heatslave 12/14 starting to blow fuses in plug socket....turn boiler on with new fuse it goes through exhausting chamber but when turning on heat control it blows fuse....new motor and fuel pump fitted 4 months ago....thinking it may be the pcb or high tension electrode leads...Selectos D11 burner...anybody....

 

[ianmcd]

very much doubt it will be the pcb

 

[ianB59]

Going to check condition electrodes / leads etc....maybe it's the transformer..old boiler but was going well after new motor and fuel pump....maybe replace with younger model...can't afford new...

 

[ianB59]

Boiler....not the missus....

 

[ianmcd]

unplug all the 240 volt components from the pcb , if you do not have a multimeter to check for a short circuit , plug them back in 1 at a time until the fuse blows and that will be the component that is shorting, most common are water pump or diverter valve actuator, if you have been topping up the system water pressure then most likely the diverter valve cartridge is leaking into the actuator motor

 

[ianB59]

Ok...new diverter valve fitted 6-8 months ago so will dust off multimeter and refresh myself with checking for shorts....thanks

 

[ianB59]

It seems that the pump is showing resistance...but when I disconnect it from the main board the boiler still tripping blowing fuse....even when I disconnect pump and diverter valve....still blowing!!

 

[oilhead]

If the control box completes the prepurge and then blows the fuse, then transformer or solenoid coil are favourites. If you disconnect the solenoid lead from the pump, and it just goes to lockout, replace the coil. If it still blows the fuse, disconnect the transformer from the control box base. If lockout, you've found the rogue, if fuse blows, then get your multimeter out and check the pcb. With a D11 burner, you probably have a post purge pcb, these can be trouble. if that is the fault, wire the burner without it.

 

[ianB59]

Thanks will persevere with your suggestions....

 

[ianB59]

You were spot on oil head....its the transformer which is rogue....with it disconnected its continually going to lockout and fuse not blowing after half dozen attempts.....now to try and source a new transformer...any ideas? 25 year old Part no under worcester spares is JFPJT159X....

 

[oilhead]

You may still find a conventionally wound unit, but you will easily get a Danfoss EBI with kit to adapt the electrode leads and some sticky pads to attach it to the burner. Be sure to specify 'with conversion kit' Cant remember if the D11 uses the transformer as part of the burner case, but if it does just leave it there with everything disconnected.
Plenty of scope on Ebay, also for direct replacement. You will need all the numbers after '52L' as there are several versions of the original regarding lead outlets.

 

[ianB59]

Yeah thanks, managed to get all details off old transformer and sourced one as below numbers all the same...
Danfoss 052L0003 Transformer 220V
Danfoss
Product Code: C02024U
£46.50

Thanks for yours and everyone else's help... much appreciated

 

[ianB59]

transformer was bolted onto D11 burner case plate with two screw bolts...