replacing an old kitchen extractor fan with a humidistat fan

11 Jul 2007
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United Kingdom
Hi All, I'll try not to make this too longwinded, our Kitchen is in a cellar and has allways been a damp place, the present extractor fan in the kitchen is vented directly out of an external wall which vents externally about 250mm above ground level. this fan is now broken and we would like to replace it with a humidistat type extractor fan. the present fans power is fed via the ring main from the floor above and comes down to a switched fuse then on to the extractor, we operate the fan via the switched fuse, all cables to and from the fan are in the walls, any suggestions as to the simplest to wire a new humidistat fan, Ican probably manage to feed a new cable from the fused switch to the fan via the existing conduit, would it then be possible to buy a three pole switched fuse? open to any ideas

thanks John
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Buy a 6 inch centrifugal humidstat fan with a pullcord.

Then you can disconnect the old fan, and take the live neutral and earth into the new fan and control it with the pullcord.

Obviously the spur will be left on all the time, and the fan will start if humidity builds up in the room.
I recommend Vent Axia centrif. They are noisy, but are very powerful.
Thanks for the info londonboy, we already have the fan its a Domus 100, H1
Humidistat wall fan, if it looks like we have to chase out the walls for three core and earth, I'll just wire it direct and control it as before from the switched fuse.

thanks John
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Hi, I was just talking to a neighbour who also has his kitchen in the cellar, he says that he tried a humidistat type extractor a couple of years ago, and from the time it was fitted it didn't seem to ever go off because of the humidity levels in his kitchen, the only way he could control it was to turn down the humidity control, but it still ran for so many hours a day he had to pull the fuse, as a result he had it wired direct from the fused switch and just turns it on when he requires it.....
You would have been better buying a fan which has an integral pullcord.

Yes the humidity stat is variable.

You must have a severe condensation problem if it runs continuously, I fit these in properties after damp proof works and they don't run all the time.
Hi Londonboy, yes your right about the pull cord type, I may exchange mine, your also right about the dampness, my neighbour had the biggest damp problem, which was initially hidden behind tanking, this lasted some years but eventually damp came through, it was then sealed using oldroyd cavity drainage membrane then dry lined, he's problem is much worse than ours as three of his external walls have soil backed up to them to 6ft in height, the DPC is well and trully bridged, so he's only putting a sticky plaster on his problem. in our case we do have a retaining wall that holds back soil, but it still always seems muggy.

thanks John

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