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So, the shed/shop is almost where it needs to be (just an inverter/VSD for the bandsaw, and I'm basically good to go), were it not for the humidity.

Now, I'm keeping most of the projects indoors, ditto wood that's cut down to size and that I plan on using soon, but large lumber is staying outside, in the unheated, humid shed. There's no mold, no water dripping off any walls, all surfaces are dry (save for two tiny spots along the floor, where there's a bit of seep from the dirt that's against the other side of the wall. And the freezer box has condensation on the side, like, but that's to be expected). It has 4 or 5 small 'ventilation ducts' currently sealed with expanding foam, but the humidity (with current temps hovering around 6-9 degrees celcius) remains at around 80-90% humidity. Pointless non-electric dehumidifying salt things do, well, diddly, so I was considering an electric dehumidifier, just to get things within more normal ranges.

Any European folk, in particular (given the climates) have anything to share about costs of running these things? The space is small (12-15m2), and pretty well sealed off (with the ventilation ducts sealed with expanding foam), so I think even a small dehumidifier would do (and I don't have space for a large one anyway), but it's the cost of operation that worries me. How constantly would it need to be on? Cycle it on a daily/weekly basis?

I don't really feel the need to keep the outside shop at a constant 40-50% humidity for building year-round, because I simply don't have the time, and I do have the indoor 'dry room' space. But 80-90%RH, in these wet winter months, does no good to my tools, is less than ideal for my rough timber, and may invite in nastiest such as mold and rust to stick around and wreak their own forms of havoc.

So. Thoughts? Reccomended dehumidifiers that are relatively affordable, reasonably energy efficient, and above all compact? Oddly, my previous 'shop' (ie, my attic student room in Amsterdam) was perfect for building, in terms of humidity and temperature. A completely unsuitable space in every other way, but perfect for that :-)

If I get the cables hooked up, I'll post some pics of the 'new shop' (now complete with dust collector!) tomorrow, for those interested. Still needs organising, but the basics are there.

Gee Mattia, that shop humidity situation is difficult.

I have six mil plastic sheeting ceiling and all four walls under my sheetrock. I run a dehumidifier in the summer and a humidifier in the winter when temps freeze up outside.

Maybe someone will have some pointers for you, I'm stumped.

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http://www.dickeyguitars.com

Mattia,

Hope the recovery is going well.

Before you decide on a course of action for controlling humidity, I'd get the
temperature up, as that alone will affect the humidity reading you're getting.
Maybe decide how warm you're going to try to keep it, bring it up to that
temp for at least a week to dry the place out, then see what the humidity is.
You might get a pleasant surprise.

_________________
now known around here as Pat Foster
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http://www.patfosterguitars.com

Food for thought, thanks guys.

I'm not going to insulate the whole thing 'properly', or heat it year-round (seasonal builder and all), but I do need to add some for of heater, and some get-the-water-out machine. I do know raising the temp (small electric heater) did help quite a bit (hit the mid to high 70's).

Heat's a good thing here; in the summers, humidity is a much more reasonable 50-70% (spot checked this year); we get very wet winters here.

Mattia, I keep all of my wood, including stuff I'm working on in a small spare room in the house. I run a small dehumidifier in it a 12l/day machine and I only have to empty it (it can be plumbed in) once a week or so in UK conditions. It manages to hold the hunidity level very well considering it's size. Power consumption is about 200W at full power. I was skeptical about whether it would handle the conditions sufficiently, but have been very pleased with it over the last year or so. As you know I'm in Kent so conditions are similar to yours, I have it on all the time and it just turns itself on and off as needed.

This is the one I have.

Dehumidifier

ColinColin S39089.1879513889

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Mattia,

A relative humidity of 85-90 percent, with a temp of 6-9 c is actually fairly dry.

Don't forget, RH is the not the absolute amount of mositure in the air, it is the amount relative to what the air can hold at a given temperature. If you were to warm that same air mass up to 23C you would see the RH drop to 34 percent. The air didn't become drier, it just can hold more moisture at the hotter temperature.

A better way to keep tabs on how moist the air is is to watch dewpoint. If you are in the 4-9C degree range it is good. Less than that is on the dry side, more than that is humid. (you are around 1C)Joe Beaver39090.0018171296

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Joe Beaver
Maker of Sawdust

Ah. OK, puts things in some perspective; knocking the temp up to 14 degrees (about all the tiny, tiny electric fan heater I have will do) dropped the RH to around the 70%. It's not actually wet, nor does it 'feel' all that wet in there. No mould, dankness either.

That's right!! What you feel is the absolute humidity, measured by dew point not RH. With your conditions I'd guess your lips are a little chapped and your hands rough. Your wood feels the same thing, it thinks it is dry, and it is. RH stated without temperature is meaningless.

These values all represent the same absolute humidity (the water vapor that is present in the air. And they are all DRY!!
Temp   RH
30c - 19%
20c - 34%
10c - 66%
5c - 93%

The only thing that changes here is the temperature, not the amount of water in the air.

_________________
Joe Beaver
Maker of Sawdust

Mattia

When I asked about RH a few months ago Tom Morici posted the following which may interest you. It shows how the moisture content of the wood changes at different RH and temps (apparently you need to aim for 8 MC.

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Richard

Mattia,

It sounds like our climates are relatively similar. I have a small dehumidifier
that keeps my shop right around 42%-46% without any trouble, but it must
be said the single biggest jump in efficiency was gained through sealing
everything up tight. Once I found all the little gaps and filled them with
spray foam and properly sealed around the doors, I went from emptying the
dehumidifier every 2 days to about every week. I was pretty amazed how
much moisture was creeping in through tiny cracks. Good Luck!

Cheers,
-Dave