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Dehumidifier

Posted: Sun Jan 12, 2020 10:38 pm
by Mr B
Evening all,

Quick question, anyone here recommend a good dehumidifier for a garage, I know alot of you guy's keep your pride and joys in a garage, so, any recommendations?

Cheers

Wayne

Re: Dehumidifier

Posted: Mon Jan 13, 2020 11:50 am
by stevemarl
I have thought about this myself in the past. The trouble is, as most are unheated, I always worried that as you`re drying the air going through the machine you`re going to be getting damp air coming in from outside, it would be hard (I`d have thought) to keep up with it I mean it`d be coming in as fast as you were extracting it? Or am I just on the wrong track? I can see how in a house it would work, but a cold garage with cold damp air all around it? TBH, if you have decent ventilation and insulation esp. in the roof, damp shouldn`t be too bad. (My neighbour recently put up a steel garage - now THAT is damp! A steel roof with a cold wind blowing across it is like a heat exchanger, the water literally runs off all over the car; still I think the wind is completely dry by the time it reaches mine so every cloud and all that. (every cloud... :lol: )
I`d be interested if anyone`s got experience with this?

Re: Dehumidifier

Posted: Mon Jan 13, 2020 12:19 pm
by pbar
stevemarl wrote: Mon Jan 13, 2020 11:50 am (My neighbour recently put up a steel garage - now THAT is damp! A steel roof with a cold wind blowing across it is like a heat exchanger, the water literally runs off all over the car
Yes totally, with metal roofing/walls, cold metal on the outside, warmer temp on the inside will attract a textbook case of condensation. Warmer air meeting cold. Metal corrugated roofing is sold now with a felt backing to eliminate this. You can get anti condensation paint also. As you have seen Steve, I have 'lined' mine with four inch rockwool, was a perfect result, stops the warmer air meeting the cold surface - that's what you need to do to stop condensation, good insulation too, and sound proofing also which is important, not only for yourself but for others when making some noise in there :)

Not sure about the feasibility of dehumidifiers in a garage, would have thought it would need emptying several times a day. I think a better option would be to warm the area up, old carpets or similar on the floor, stop any large draughts, insulate walls/roof.

Re: Dehumidifier

Posted: Mon Jan 13, 2020 12:53 pm
by tejb1
I am very lucky in that my garage is in the basement of a block of flats and the heating pipes for the flats pass through the garages. This gives just enough heat to stop it being too cold, takes the edge off it to an extent. I've also put two old carpets down on the floor (thanks to having a carpet wholesalers on the end of the road!). There are draughts through the grilles, but it never seems too bad.
In the car itself, I simply have one of those crystals-based units which are two for a quid in the pound shop, which stops it getting too damp (especially in winter after use etc). Empty every month or so.

Re: Dehumidifier

Posted: Mon Jan 13, 2020 1:19 pm
by pbar
tejb1 wrote: Mon Jan 13, 2020 12:53 pm In the car itself, I simply have one of those crystals-based units which are two for a quid in the pound shop
Aldi do a small rechargeable unit version of that. Works very well actually, for a car which is stored outside, etc.

Re: Dehumidifier

Posted: Tue Jan 14, 2020 1:20 am
by Mc Tool
Two things to be aware of
Moisture in air will flow ( without moving any air ) from high concentration to low concentration better than just about everything else ( so unless the area your trying to dry out is hermetically sealed your largely wasting your time)
and condensation forming on insides of a shed is only indicative of the moisture already there , and is probly as effective as a dehumidifier.......in that the condensation is forming on the shed lining and not your car. Air saturation depends on temp so things can appear to get wet or dry after a change in temp or pressure (basic refrigeration) . All to do with "latent heat of vaporisation " and "sensible heat "

Re: Dehumidifier

Posted: Tue Jan 14, 2020 10:51 am
by stevemarl
Mc Tool wrote: Tue Jan 14, 2020 1:20 am .in that the condensation is forming on the shed lining and not your car.
Not if it then drips off all over the car... ;) Seriously though, you would be struggling for the reasons you say, the humidity will tend to migrate into any areas you dry out very quickly (I`d have thought) Best thing is probably as Paul says, plenty of insulation (as air flow over exterior will `chill` roofs & walls) to try to keep temp a little higher. I have a brick garage with a wooden roof and condensation has never been a problem as it is such a poor conductor of heat it doesn`t remove enough energy from the damp air for water to condense out. (see below :D )
Mc Tool wrote: Tue Jan 14, 2020 1:20 am latent heat of vaporisation
8-) Not heard that for 40 years!

Re: Dehumidifier

Posted: Tue Jan 14, 2020 2:21 pm
by Mc Tool
:lol: thats about when I 1st heard it.