Posted by: @benseb

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So a few weeks back, we woke up to a powercut. We're on 3 phase so didn't immediately notice, but 2 of the 3 phases were off, with 1 still working.

ENWL came out and found a fault in the supply cable in a field nearby, affecting a few properties. I was out at the time, but the power was off for a good 15 hours. 

During this time the power came on/off a few times, from what I undestand was part of the repair process / pulling fuses at the transformer/etc.

However, our Ecodan hasn't worked since. We've had the engineer around who's said there's a fault code saying the External Fan Motor is faulty. As we have two in our heat pump (14kW) and both aren't working, Mitsi have said we also need to replace the PCB.

About £1000 + vat to sort.

The heat pump is under warranty by Mitsi have washed their hands of it saying they don't cover if there's a power surge (there's no proof of this, but with both blowing, they've said it's obvious). Our solar monitor doesn't show any voltage surges but I guess they might not register if short, it could just be rapid on/off causing it?

ENWL have also said they have no responsibility to the end user for consequential loss of equipment.

Has anyone else succeeded in getting any of this covered by the DNO or manufacturer? Very annoying when it's completely out of our hands but we have to stump up the bill.

Is it covered under your household insurance?

The alternative could be to get a friendly electrician to test the fan motors and see if there is any output from the PCB.

Could be covered, but by the time we pay excess, increased premium next year, etc I doubt it'll be worth it

Might be a good shout about testing the motors yes, will try that, thanks

Posted by: @benseb

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Could be covered, but by the time we pay excess, increased premium next year, etc I doubt it'll be worth it

Might be a good shout about testing the motors yes, will try that, thanks

Are there any fuses or protection devices on the PCB or elsewhere?

Posted by: @benseb

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We're on 3 phase so didn't immediately notice, but 2 of the 3 phases were off, with 1 still working.

Do you have a 3-phase heat pump? What's the model number?

Posted by: @benseb

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As we have two in our heat pump (14kW) and both aren't working, Mitsi have said we also need to replace the PCB.

It seems like a sub-optimal design if both motors *and* the PCB go up in smoke at the same time.

Posted by: @benseb

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As we have two in our heat pump (14kW) and both aren't working, Mitsi have said we also need to replace the PCB.

I presume you have some form of PUZ-ZM140YKA :- https://library.mitsubishielectric.co.uk/pdf/book/PUZ-ZM100-140VYKA_Service_Manual .

The service engineer probably followed the chart on page 60 and found a blown F5 fuse.

F5 being circled in blue on the following diagram

It seems as if the fuse is being used as an overcurrent detection device but does not serve as a protection device. Fan connections are all DC (or pulsed DC?). *sigh*