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Omnivent 12V roof extractor fan


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In Holland for another 2 weeks, my fan has packed up. It’s about 7 years old, very little used and started playing up upon pressing the on/off switch. The little LEDs on either side of the central control start flashing alternately like a pinball machine, the blades give a little jolt,- then nothing!

Any ideas you electrical guys? I’ve had the corner control unit out and inspected it but no obvious breaks or poor connections. Has this unit got a reputation for problems?

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These units do have an issue with damp getting into the electronic control panel. The symptoms you describe are exactly those I experienced on a new unit installed in 2012. Omnivent replaced three units over a period of 3 years, each suffering from the dancing lights problem. There was quite a lot of discussion on the problem on various forums at the time.


Omnivent's customer service was very good but obviously they couldn't resolve the problem of damp getting into the control panel.


2 years ago, when it happened again on my current fan, I took the various components apart and noticed that there was no waterproofing to the connectors on the control panel for the wires leading to the fan motor.


It seemed obvious that moisture could then track down the wires and thereby into the control panel via the unprotected connectors.


I dried out the control panel in the airing cupboard for about two weeks then put it back into the fan assembly to find that it worked perfectly. I then smothered the connectors, wires and the control board in silicon to ensure the whole assembly was encapsulated. I've had no problems since and use it a lot.


It's not too difficult to do and worth a try before splashing out cash on a new control panel.




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Thanks Peter,

It’s Rest and Recreation here today so I’ll strip it down. Nothing to lose.

Since my original posting I’ve been online with various forums and there are many reports of this problem. I’ll check continuity on the motor with a multi meter, check 12V input, and if both ok, it has to be the pcb switching unit even though it’s covered in a soft plastic barrier. Left my airing cupboard at home though!

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  • 1 year later...

" I might put it in the oven at 60°c for a couple of hours"


That should ensure that it reliably doesn't work !


Electronic components don't like heat & 60 degrees is over normal operating temperatures - IIRC from college (a long time ago !) every 10 degree C rise over over 30 degrees C halved the working life. At my last employment, another department repaired industrial pcbs that usally arrived filthy - they were washed under running water with a brushed-on cleaning solution then dried on racks in a cabinet that just had a couple of fans to circulate room temperature air. No addition heat was used to dry them & I wouldn't go hotter than a domestic airing cupboard.


Nigel B

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I said 60°c because it will be ok (IMO)

It will be easily capable of working at a higher temperature than that.

The electronic test chambers I've worked on typically run the PCBs at 80°c then plunge them into the lower chamber which is at -80°c... All while powered up and plugged into a PC, they run the test cycles say every 40 minutes 24hrs a day for three months 8-) and it all has to work perfectly.


So it should be a walk in the park for it... OK I'll lower it to 50°c then in case it's made in Italy :D

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