I have had some problems with rust on my tools (tablesaur, jointer) in my
shop in the last couple of springs during the rainy damp season. So this
year, I picked up a used dehumidifier for $20 (it even works!) Today I
bought a digital temp/hygrometer from the hardware store and it said my rh
was around 77%. I let the dehumidifier run for a few hours and it is down
to about 60%.
So the question is, what do you try to keep your shop at? In the latest
issue of FWW, there is an article on wood (go figure) and a graph comparing
moisture content to relative humidity. It looks like a rh of around 50%
will keep lumber at around 8-9% or so. I was thinking this would be a good
benchmark to shoot for.
So, what do you all do? I know some of you live in climates much more humid
I do nothing. My shop is in a detached garage. In the warmer weather, I
work with the side door and the overhead door open so whatever the RH is
outside, it is the same in the shop. In the winter, the only time it is
heated is when I'm going to be out there.
I'm sure it is not the best way to keep wood, but it would be costly to try
to control the environment all the time.
Yep 45% RH is preferred for wood storage.
Remember that it's _relative_ humidity that counts. You can beat the curve
by warming the air or lowering the absolute. I strongly suspect that
efficiency favors the first approach. Makes the occupant more comfortable,
Oh yes, make sure that your dehumidifier is the kind that defrosts itself,
or it could run and run and run ....
There is no more humid climate than Michigan - near the lakes.
Here in central Ohio, a 50% setting seems to make the dehumidifier run
nearly constantly. I've set mine at 55%, which has eliminated the
problems I was having with light surface rust and wintertime window
condensation. A very nice bonus is the increased comfort level in the
summer. Since I no longer feel like I'm wading through a swamp, I have
given up the idea of putting in a window air conditioner. The standard
August cliche around here is "It's not the heat, it's the humidity".
My shop is nearly airtight, so I doubt a dehumidifier would work very
well those with more open shops or garages. I know simply opening the
door for a couple minutes can raise the RH to 75-80%.
A cautionary note to those that may be shopping for a dehumidifier:
some of the electronic control models will not restart themselves
after a power outage. I bought an electronic Maytag because it
advertised working in low temps (I keep the shop around 50 degrees in
the winter). We have power "flickers" in our area every 2-3 weeks
which shuts down the dehumidifier until I get back out to the shop.
I like to keep it simple and so far it has worked out just fine.
When I have a job going I keep my shop comfortable to work in. No more heat
then necessary in the winter and no more air conditioning then necessary in
For the most part that is the circumstances the pieces are going to have to
I don't know for sure but I'd feel safe in giving good odds that 0% of the
people receiving my output check the conditions in their house with a
digital temp/hygrometer and most strive to just feel comfortable.
I live in Houston and the relative humidity often reaches 100% and is
normally above 80%. I do nothing to try to reduce the humidity. I do use
TopCote with great results. I think good air circulation and slow
temperature change may be the answer.
I use a Santa Fe brand basement dehumidifer, one designed for larger
areas (like a basement!) than your typical home dehumidifier. It cost
Mind you, I have thick stone walls for a basement, not the "typical"
8-10" thick concrete walls. Mines about 18" thick. It really traps the
humidity in the summer, and even though its cool, the humidity would
have you sweating as if you were outside in the sun. Rust was a constant
problem also. I tried in the past to use regular dehumidifiers, they
either filled up too fast, or put out so much heat, that they were
Now, with this dehumidifier, I keep the RH about 50%, its dry and cool,
the water the dehumidifer pulls goes down the laundry drain (has a pump).
BTW guys, simply increasing ventiliation to your workshop isn't going to
reduce humidity. It will be the same as your outside humidity.
The out side humidity is not the problem if you are circulating it in your
shop and allowing it to keep the temperature in the shop about the same as
it is outside. It is when there is a drastic change in temperature that the
humidity condenses on the tool surfaces.
I've got a regular consumer model I got at Sears. Yes, it does put out
a lot of heat, but it's hard to avoid that; that's how dehumidifiers
work. Mine runs about 6 months a year (in my basement). Once the
ambient temperature in the shop gets below about 60 degrees, you can't
run the dehumidifier any more because it just freezes up. But you don't
need it much in the winter, so that works out OK.
As for the emptying problem, that's easy. I've got mine mounted up high
enough that a short length of garden hose leads from the collection
container into a sink.
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