My supervisor sent me and another engineer to fit a fan he diagnosed to an M series ICOS earlier on. Fitted the new fan and BANG! Blew the board. So I checked with Parts Centre to make sure I had the right fan, which was wrong. The engineer I was working with had one on the van, so we swapped it over and put another board on it. It fired up and then BANG!
Switched it off and it wouldn't fire up again. I'd already checked the continuity between the wires and there wasn't 140v DC at the fan, so I thought the wrong fan had blown the board. So I began looking further and tested continuity between each wire with another. Bingo! Continuity between 2 wires. So the wiring loom is at fault. But why? Oh, here's why!
As you can see, the insulation pad has fallen, causing the downward fire to deflect to the alu combustion chamber, melting it in to a hole and then melting the wiring loom! The alu was actually soft, I could crumble it with my fingers. To look at it, you wouldn't have seen any of this due to it being at the rear, it was only when I took the burner off I found it. I've heard of this happening before, but have never seen it and I have been checking them every time I do something more than topping up the pressure.
The cause is the earth pins, which also act to retain the insulation pads. On the M series and early HE boiler, the pads were squared off, so easily fell in after time.
This is a serious situation, the things could easily melt completely and the copper gas pipe sits behind it. I recommend that EVERY time you work on one of these boilers, you take the fan and burner off and inspect them. Any kind problem, AR them and get the replacement parts (which have now been redesigned).
Switched it off and it wouldn't fire up again. I'd already checked the continuity between the wires and there wasn't 140v DC at the fan, so I thought the wrong fan had blown the board. So I began looking further and tested continuity between each wire with another. Bingo! Continuity between 2 wires. So the wiring loom is at fault. But why? Oh, here's why!
As you can see, the insulation pad has fallen, causing the downward fire to deflect to the alu combustion chamber, melting it in to a hole and then melting the wiring loom! The alu was actually soft, I could crumble it with my fingers. To look at it, you wouldn't have seen any of this due to it being at the rear, it was only when I took the burner off I found it. I've heard of this happening before, but have never seen it and I have been checking them every time I do something more than topping up the pressure.
The cause is the earth pins, which also act to retain the insulation pads. On the M series and early HE boiler, the pads were squared off, so easily fell in after time.
This is a serious situation, the things could easily melt completely and the copper gas pipe sits behind it. I recommend that EVERY time you work on one of these boilers, you take the fan and burner off and inspect them. Any kind problem, AR them and get the replacement parts (which have now been redesigned).