Truma Combi Boiler Fuse Issue

[Dave Scadding]

Hi all,
I have a problem which is when I turn on the power at the control panel the 10 amp fuse (Nr4) on the Sargent PSU2007 blows. I have disconnected the feed to the Truma boiler and the fuse is ok. My question is does anyone have any idea as to why this is happening or have had the issue themselves. It was all working fine until I reversed into a tree on holiday damaged a rear marker light which blew the same fuse. I disconnected the remains of the marker light replaced the fuse and all was ok for the rest of the holiday. When we returned home I replaced the rear marker light and all was well until now. The two issues may not be connected and may be just coincidence. The 2 core feed wire to the Truma is fine otherwise the fuse would have blown when discounted and the fuse replaced. So I'm looking at the boiler or the printed circuit or something?? Anyone have any ideas? (Don't suggest better reversing cam)!

 

[Phill D]

if the same fuse blew when the marker light was affected then there must be some electrical coloration between the 2 circuits.

have you tried disconnecting the new marker light and turning on the heater, just to absolutely discount the marker light.

 

[RandallC]

Hi,

Is this the 240vac supply fuse?

If so could be a couple of issues, only way to find out is to section the supplies and test .

Most likely one of the elements in the combi boiler has failed

 

[WASPES]

Did you put a 10 amp slow burn fuse back in.

Peter.

 

[Phill D]

I believe fuses on this unit are all 12 v DC fuses.

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[WASPES]

Changed a fuse in mine 3 days ago they are special fuses.

Peter.

 

[Dave Scadding]

if the same fuse blew when the marker light was affected then there must be some electrical coloration between the 2 circuits.

have you tried disconnecting the new marker light and turning on the heater, just to absolutely discount the marker light.

if the same fuse blew when the marker light was affected then there must be some electrical coloration between the 2 circuits.

have you tried disconnecting the new marker light and turning on the heater, just to absolutely discount the marker light.
Yes the marker lights work fine and don't blow fuse

 

[Dave Scadding]

Hi,

Is this the 240vac supply fuse?

If so could be a couple of issues, only way to find out is to section the supplies and test .

Most likely one of the elements in the combi boiler has failed

No its a 12V Red spade fuse

 

[Dave Scadding]

Did you put a 10 amp slow burn fuse back in.

Peter.

No the fuse in the Sargent is a normal Red 10 amp blade fuse

 

[WASPES]

Sorry I thought you meant the 10 amp fuse in the Truma heater.

Peter.

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[Dave Scadding]

Sorry I thought you meant the 10 amp fuse in the Truma heater.

Peter.

No, they seem to be ok,
Thanks Pete.

 

[RandallC]

With sort of problem often use a lamp to replace the fuse that normally draws more current than the device/circuit draws.

The lamp shows when current is draw and goes out / dims when none/less So indicates when you disconnect stuff where the short maybe.

Good luck

 

[Lenny HB]

The two problems won't be linked as the marker lights will be running from the chassis electrics not the habitation circuits.

It could be a faulty fan motor there are 2 the blow air fan and the flue fan. You could try disconnecting each fan in turn and if the fuse still blows. Failing that if it's the pcb it will be expensive £300-£400 for a new board.

 

[Dave Scadding]

The two problems won't be linked as the marker lights will be running from the chassis electrics not the habitation circuits.

It could be a faulty fan motor there are 2 the blow air fan and the flue fan. You could try disconnecting each fan in turn and if the fuse still blows. Failing that if it's the pcb it will be expensive £300-£400 for a new board.

Ouch! I’ll check both out.

 

[Dave Scadding]

Thanks for all your suggestions, problem now sorted. It was part of the wiring loom shorting out on the boiler frame!

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