Sime combi fuse keeps blowing

[armyash]

Went to this boiler yesterday, 240 at the board coming in.

2amp fuse had blown.

replaced the fuse, it blew again the second we switched it on.

Back there tomorrow with a load of 2 amp fuses and have a new pcb just in case. I have been advised to unplug the different components until the fuse stops blowing, this should indicate what is causing it to blow.

i have a fan also just in case but can send that back if I'm wrong.

any ideas to begin with?

thanks

 

[armyash]

I have seen on y plans etc when the power trips when boiler switched on it's been the pump, so it could be that I suppose

 

[Billy Bob Bob]

start with pump,divertor,anywhere water and electric can mix,next move onto fan and gasvalve,not likely to be pcb,unplug each in turn

 

[armyash]

Ok thanks. I have 20 2amp fuses should be enough.

 

[Billy Bob Bob]

Ok thanks. I have 20 2amp fuses should be enough.

basically you have a dead short,with mains off,test between N and E on components should not see continuity,you will see it on L and E though,unplugging and testing in turn just as quick though

 

[lame plumber]

not teaching gm to suck eggs, but safer to unplug the lot and connect up one by one in the order you expect things to run up in ie fan,ignitor gas valve etc, saves causing a bigger cockup when the fuse doesnt blow in time

 

[Billy Bob Bob]

not teaching gm to suck eggs, but safer to unplug the lot and connect up one by one in the order you expect things to run up in ie fan,ignitor gas valve etc, saves causing a bigger cockup when the fuse doesnt blow in time

its a combi,pump will be the first thing to run,this is why i pointed this out first

 

[lame plumber]

not contradicting you, just saying, unplug the lot and plug in in turn, saves stressing bits n bobs further, just coz you stayed on field a bit longer

 

[Billy Bob Bob]

not contradicting you, just saying, unplug the lot and plug in in turn, saves stressing bits n bobs further, just coz you stayed on field a bit longer

agree disconnect in order of sequence ,makes sense water carrying parts always the first suspects though

 

[armyash]

Good stuff thanks, am thinking pump or fan most likely.

Will update later, assuming the Job hasn't been rescheduled.

 

[armyash]

Pcb was the culprit. Had another job exactly the same after, different boiler obviously. Fuse had blown. Disconnected all components, fuse still blowing.

Been doing reasonably well on the fault finding lately, not the most complicated jobs but it's all good experience. Dodgy pumps, seized fans, pcbs, controls. Easy stuff for you guys but it's all good experience and have to start here, another 6 months and these jobs will be second nature.

Thanks for the replies.