Dehumidifying large shop area

[CrashTestDummy]

We have a 40X80X20 steel building that's our shop for storing our 'collection' and for our projects. We had it built in 2009. The shop itself is insulated on all walls and the ceiling (3" fiberglass insulation). It has a concrete floor.

We live in the Texas Gulf Coast and humidity is a REAL issue. The relative humidity can also wildly swing from one extreme to the other quickly.

In the winter, when the building and slab cool, and the wind is out of the south, there's a LOT of condensation on the floors. So much that you're sloshing around in places. It's annoying, and really problematic when I have to get under a car to do work (we're still planning for a lift, but that hasn't materialized yet. The condensation isn't good for the cars, either.

I have three 72" ceiling fans that I did try turning on this year, on low, just to keep the air moving in there. They were blowing downward, and I don't think that helped at all. I recently switched the direction, and will monitor progress, but I'm still thinking I'm just moving wet air around in there.

I've been looking around a bit, but haven't found anything that isn't an arm and a leg to get and use. Even the 'large building' dehumidifiers only talk about maybe 1200 sq. ft building sizes. Maybe even one of those would be better than nothing, but I don't know.

I'm wondering if there are any solutions out there. While I don't really need heat, or A/C, they can be handy, but the main thing I need to control is the humidity. What are the options for such a large building?

Thanks.

 

[sledneck32!]

Is ur slab insulated underneath? Vapor barrier? Just insulating underneath will cut back 90% if not 100% of your condensation problems because itll allow your slab to warm up to near the ambient temp instead of staying at ground temp which is likely 55 to 60 degrees.

I have an independent dehumidifier in my house, hooked into the duct work. Its a bigger one from honeywell and does a good job in our 1400 sq ft rambler. Keep in mind that using a dehumidifier will usually increase the air temp in the building. If we just let ours run the house will go from 70 to 80 in about a day. So the ac has to be running at the same time for us. Mine was about 2000 dollars installed.



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[theoldwizard1]

Forced air furnaces do a good job of dehumidifying, but you probably don't want the inside temp on the 80s during winter with no help in summer.

 

[CrashTestDummy]

Sled, yes, the slab has a vapor barrier, and it is coated with epoxy, which makes is even more fun when it gets wet. =8-0

Having the temp go up in the winter time will usually be no problem. Moisture in the summer time usually isn't an issue, either, as it is hot enough to keep the water from condensing. I'm surprised that they do cause the temp to increase, I thought they made the water condense on an evaporator and pumped the water out of the building.

 

[bzinsky]

We have a 40X80X20 steel building that's our shop for storing our 'collection' and for our projects. We had it built in 2009. The shop itself is insulated on all walls and the ceiling (3" fiberglass insulation). It has a concrete floor.

We live in the Texas Gulf Coast and humidity is a REAL issue. The relative humidity can also wildly swing from one extreme to the other quickly.

In the winter, when the building and slab cool, and the wind is out of the south, there's a LOT of condensation on the floors. So much that you're sloshing around in places. It's annoying, and really problematic when I have to get under a car to do work (we're still planning for a lift, but that hasn't materialized yet. The condensation isn't good for the cars, either.

I have three 72" ceiling fans that I did try turning on this year, on low, just to keep the air moving in there. They were blowing downward, and I don't think that helped at all. I recently switched the direction, and will monitor progress, but I'm still thinking I'm just moving wet air around in there.

I've been looking around a bit, but haven't found anything that isn't an arm and a leg to get and use. Even the 'large building' dehumidifiers only talk about maybe 1200 sq. ft building sizes. Maybe even one of those would be better than nothing, but I don't know.

I'm wondering if there are any solutions out there. While I don't really need heat, or A/C, they can be handy, but the main thing I need to control is the humidity. What are the options for such a large building?

Thanks.

I have no experience with it, but apparently Daikin Quaternity mini split heat pump offers humidification in both heating and cooling mode.

Just a suggestion, you could always just buy the dehumidifier and see if it takes "enough" out and just buy another if it doesn't. I mean two dehumidifiers in different locations are probably better than one big one anyway.
You could also spend a day just sealing the place up better as well.

 

[manwithtools]

You would want an air conditioner to reduce the humidity inside the shop without adding heat to the area. The AC unit has as cooling coil that is colder than the surrounding air causing moisture to condense on the coil and drip onto the condensate pan.

The condensate then is drained or pumped outside the air conditioned space. Most heat pump units will work this way even in a heating mode if the humidity is high and your thermostat has humidity detection and control capabilities.

 

[manwithtools]

Dehumidifiers do actually add heat to the space they are operating in. This is because the evaporator and condenser are in the same self contained unit inside. The thing about heat pumps or mini-split heat pumps is that the condenser unit (and the heat it produces) are outside the conditioned space, the evaporator is inside the conditioned space.

 

[JCoggin]

I bought a Sante Fe Classic dehumidifier for my basement. It's a commercial unit but it is a serious workhorse. Basement is 64'x28x10' but my unit can handle much more than that. Ran me about $1600.00.

JC

 

[CrashTestDummy]

@bzinsky: Yeah, one dehumidifier then another, if necessary may be the way to go. Not sure about sealing it up any better. The big holes are the three garage doors, one of which is RV-sized. They are pretty-well adjusted. I'm not sure there is a way to seal them up any better than they are. I'm open to suggestions there, though. The man doors are pretty good.

There are no windows in the shop. I'm trying to see how things are with the roof vents closed, but don't think that's made a difference in the past.

@ manwithtools: Yeah, I forgot about the condensing unit end of the dehumidifier in the same box as the evaporator, all that energy has to go somewhere. But again, the humidity is really only a big deal in the winter time, so making things warmer won't be a problem, and if it's drier inside, the heat won't be felt as much.

@jcoggin: Thanks for the information. They also have a larger unit that's over $2K, but offers higher efficiency (higher pint of water per kwh). But I could probably start with a Classic and see how/if that helps.