Sime Super 102 Blowing PCB 1.6A Fuse as soon as HW or CH called

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msflsim

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Hi guys

A few months ago the boiler stopped working and it turned out to be a blown F1.6A fuse on the PCB. Replaced that and it carried on working fine for a few months.

Last night however again it blew the fuse but now when i replace the fuse everything is ok until i call for hot water or the central heating comes on. Yesterday it would work for a few minutes then the fuse would blow. I have connected the pump on its own with a 3A fuse in the plug and it runs fine.

I have removed the fan which moves fine, doesnt make any noise but when i put it back, the fuse blows instantly after hot water is called.

Could it be the fan? Ive inspected the PCB visually and there is no buildup or anything like that.

Help!
 
Unfortunately a DIYer should not have opened the combustion chamber and touched the fan.

I would suggest you turn it off and call a gas registered engineer.

Tony
 
Hi Tony

Thanks for the reply. I have already replaced the fan in the past once, replaced the air pressure switch at another and the diverter valve twice!

I have removed the fan and connected it to the mains with a 3A fuse and it works fine! Although the coil gets a bit warm.

Still not anywhere closer to solving this
 
Connected the fan back and replaced the fuse and the heating & hot water ran fine for 15 minutes or so and then it went again but this time there was a burning smell coming from the fan

I am 90% sure its the fan as when i measured the resistance between L and N it was 28ohms

Heeeeelllpppppp :)
 
Most simple fans are about 40 ohms. But that is purely the DC resistance.

When AC is applied, the current is limited to less than 1/2 amp because of the inductance of the winding.

Yours probably has shorted turns.

Even so you should not be replacing it yourself.

Tony
 
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