Ideal Icos m3080 blowing fuses

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Order a new pcb and fan harness.

Thanks again.

Replacement pcb now here.
I have extracted the fan harness and that is the source of the short to earth.
The wires had melted together around a section where a cable tie was bunching them together.
I'm working at the replacement.

A couple of queries about it. Seeing some pictures of new harnesses, they seem to have a black shroud around the wire group (heat shield?).
Did they always have that ?
The one I have just extracted hasn't - which may explain why it has melted.

Looking at the boiler assembly exploded view in the servicing manual, I see the fan harness is routed between the mounting box and the interplate. Should there be anything to help keep it towards the wall & help prevent it getting too near the burner assembly?
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Thought I'd come back to report that the icos 33080 is now working again.
It was rather worse than it appeared.
When replacing the fan harness, I looked for where the cable should be attached to the case, and noted a plastic clip top left of the case which had been charred.
I also found the long hexagonal central pin holding the burner on was loose. These were obviously of concern, so I reluctantly unscrewed the burner top.
Good job I did - fully one third of the box underneath the left of the burner had melted away, causing a gaping hole at the rear that was completely out of sight, charring the interplate, knackering the burner gasket and even causing a positive feedback loop by heating the gas inlet pipe.
It had been caused by the rear insulation panel tilting forward.
Unbelievably, the side panels which retained it in position had chamfers cut which enabled this movement to happen, exposing the aluminium casting directly to the combustion region.
So, not the PCB, not the fan, not the harness, but poor insulation design causing subsequent failure of the burner box, harness, fan and PCB.
I later accidentally stumbled on
this thread
(with picture) on another forum which described pretty much the same issue - but mine was rather worse.
It even looked like one or two of the vanes in the HE casting had possibly started to melt.
I sourced a complete HE+burner replacement, plus all the gaskets, and a Gas Safe engineer who was experienced in Ideal boilers who has put it all back together safely.

I'll start another thread about how to identify an alternative boiler to replace this one at an appropriate time.
Well done on the diy gas repairs.

Im surprised you didnt find this fault or even better prevent this fault form happening when you had the boiler serviced correctly?

Another example of why people should have boiler serviced correctly once a year and leave gas work to people that know what they are doing!
Another example of why people should have boiler serviced correctly once a year and leave gas work to people that know what they are doing!

If you look at the thread I cited, you'll find that experienced/conscientious engineers were unaware that this could occur, or that opening up the burner on an annual service was now recommended.

The engineer who just put it back together was similarly ignorant, despite being very experienced on such boilers.

There is NO guarantee that having it annually serviced by even a good engineer would have picked this up.
Take your head out of the clouds, this would have been picked up at at service.

An combustion check alone would have picked it up.

There's an old corgi tech bulletin about the insulation on these boilers must be checked,

Strange how this gas eng knows to check it?!

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