Question for woodworkers in humid climates

The Texas heat is bad also. My mini-split idles back and only kicks on when needed. I leave it running most of the time. All four walls are insulated, as is the ceiling (R-38).

Good luck. Believe me, you will love having that thing to cool the room down.

Gets warm in Maryland too - 95° yesterday, and they're forecasting 97° today - and I don't know how I got along before I installed the mini-split. It's really not that expensive to run - walls are insulated, and I have 15" in the ceiling - but, as has been mentioned, it's a cost of the hobby. My Mitsubishi has a "dehumidify" mode, as I'm sure most makes do - I've never run it just on dehumidify but probably should at least try it on days when temps are down a little but it's still humid. It also has an "Eco-Cool" setting where it ramps the temperature up by 6° over some hours, I've used that when I know I'll be out of the shop for a couple of days.

The utility company should be able to provide daily usage numbers in Kw - BGE does this - and you could estimate cost by turning the unit off for a day and looking at the difference in usage and then guesstimating cost based on the utility's ¢/Kwhr charge. I did a comparison one time - current month bill versus same month for the previous year, and the number was around $15 per month for my 24' x 24' shop - I have the A/C set at 76° and the unit is High Efficiency.

Having the unit now means my shop is usable year round (I used to have to take any glue and finish into the house during the cold months so that it wouldn't freeze), don't know now how I could get along without it.

The roll-up door is indeed a big potential for heat loss. There are oversize "flap-type" seals available which help, but the secret is getting the door tight to the framing. There is a company that makes spring-loaded hinges to address this problem - a little pricey, and don't fit all doors. If the track is bolted to slotted angle brackets (rather than riveted), the track can be adjusted to close up the gap, or toggle clamps can be added as shown below - probably not a good idea with a garage door opener :surprise:

With Florida air you will be dealing with both humidity and salt in the air. Both are very hard on cast iron and steel tools. You will need good insulation and a vapor barrier in the walls and ceiling with a concrete or wood floor that also has some kind of sealer or vapor barrier The overhead door or hinged doors need to be insulated and gasketed well, and you will need to keep your garage shop completely sealed up as much as absolutely possible. If you open a door (garage overhead door or passage door left open for prolonged periods) and the humid/salt air gets in, things will rust quickly. You will need a good air conditioner, probably running 24/7 for about 10 months a year, more to keep the humidity in the shop below 60%, but keeping the temperature at about 75 will be great too. Portable air conditioners are not very efficient. Ductless systems will cool well, but will have problems filling with sawdust from the air. No matter how much money and effort you put into dust collection at each tool, you will get some sawdust in the air and it will end up sticking to the cold/wet coils in the air conditioner unless you can put a good filter on the air intake and change or clean it often. A ductless system doesn't have a way to install a good filter, so you will be shutting it down and cleaning the coils often.

If you install a small home unit in the attic above the garage, a short duct elbow can attach it to a ceiling register containing provisions for a good furnace type filter. A similar elbow on the outlet, and maybe a straight section of duct could direct the outlet air back down into the shop, maybe with a Wye connector to split the air in opposite directions so it doesn't blow straight down on you. warm air rises naturally and cool air falls naturally, so distribution will not be a problem, and the filters will be in a ceiling register, so they will be easy to change or remove and clean. A system of only about 1-1 1/2 ton should be adequate for a well insulated 1 car garage shop.

Here in South Central North Carolina our temperatures are in the 90s most days in the Summer, but we do get a bit cooler than you in the Winter months. My shop is a detached 14 X 26 outbuilding with 3 1/2" fiberglass insulation in the walls and 6" in the ceiling. All of the doors windows are insulated as well. My shop is located about 100' from and about 4' above a 350 acre lake, so the humidity here is high, but I don't have the salt air to deal with. My shop is heated and cooled with a 22,000 btu heat pump window style unit mounted high through the facing North Wall. When it starts getting in the high 90's every day or will be below freezing at night I leave the unit running 24/7, but otherwise only run it when I will be working. I have a dehumidifier with a connected drain set to about 60% and able to run 24/7 365 to keep the humidity reasonable. It rarely runs when the heat pump is running.

Keeping the doors of my shop closed as much as possible, and keeping at least the dehumidifier running, keeps the cast iron and steel in my shop from rusting. I use Johnsons Paste Wax on all iron tops and unpainted surfaces and re-wax them about monthly or whenever the wood doesn't seem to slide easily. The only time that I have any rust problems is when someone places a hot sweaty hand on one of my tools. If I don't deal with it immediately, their perspiration salts and moisture will cause a rusty hand print in about 24 hours. If I catch it quick, Skotch-Brite and re-waxing will remove it. If not, I resort to using an old ROS and Skotch-Brite with a little WD-40 to bring back the proper color and then glean and re-wax the spot with several coats of paste wax.

If you can keep the doors shut and an air conditioner or dehumidifier running 24/7 for at least 10 months per year, I think you will keep your tools from rusting in Florida, but if the salt and humidity get in, your iron and steel tools will rust quickly, even if they have wax on them.

I frequently wipe my hand tools down (the ones that can rust) with a rag and WD-40 too.

If your garage is a path to the outdoors, plan on adding a passage door to the outside, before they reach the garage/shop. Don't expect to keep your tools rust free idf your wife or kids open the overhead door to get out through the garage from the house to the driveway Mine were not only opening it, but leaving the door open no matter what I said. That's why my shop is now in a separate and locked outbuilding. It was the only way to keep my tools from rusting.


Charley

Thank you all for your comments and suggestions. I have been planning to install the mini-split in the same location that Tom has since there is a concrete pad outside the door that holds the house air conditioner. I will, of course, discuss this with whoever does the installation.

I had considered installing a ceiling mounted dust filtration system like https://www.amazon.com/dp/B00LPD9BD...t=&hvlocphy=9012279&hvtargid=pla-273189533489 but I hadn't thought about dust accumulation on the air conditioning unit until Charley pointed it out.

Another "Duh!" moment for me is that when we moved south i brought along a dehumidifier that I had in the basement of my last home. It's currently sitting, unused, under some boxes in our rental home. That, along with the mini split, should do the trick. All of you have convinced me that running the unit 24/7 is the right thing to do. Just as in my house, I can turn the temperature up when I'm not in the shop. I would leave the dehumidifier running all the time. I'm not sure who my electric supplier will be in my new home but in the one I'm renting, like Tom mentioned, I can go online and see my daily usage and estimated costs.

Thanks again. You've pointed me in the right direction and I'll try not to be "penny wise and dollar foolish".

A mini split system is what I called a "ductless" system. There is no good way to filter the air going through these units, and even if you buy a shop air filter system, you will have trouble with excess sawdust building up on the moist coils of this mini split system, especially if you don't have a whole shop dust collector and piping to collect most of the sawdust at it's source. They are nice, and quiet, but not so good on air filtration. My "Through the wall" heat pump has just enough room to squeeze a 12" X 20" X 1" pleated furnace filter behind the plastic face cover, and it completely covers the cold and wet coils of the unit, so it does a great job of keeping the sawdust out of the coil.

If you can possibly put a small home style standard type split system in the attic above your shop with just enough ducting to have a filter register in the shop ceiling and the supply duct come down through the ceiling about 8' away, with a wye duct to split the air into two directions just below the ceiling, you should have a perfect set up. You will not use any shop space for the unit. You will have the ability to use high quality pleated furnace filters that are relatively low in price and easy to change in the ceiling of your shop, your noisy compressor unit will be outside on the concrete pad, and trust me, those guys who use mini split (ductless) systems in wood shops will regret it when it becomes necessary to clean the coils of the unit, A small house system of 1 1/2 tons
will do a better job and be much easier to maintain than the mini split in your wood shop.
When I'm working every day in my shop it's necessary to clean or replace my filter at least every month. I usually take it outside and with a dust mask on, I blow it out with compressed air. About every third time I replace it with a new filter. Yes, it gets that dirty.

My shop has the window style heat pump installed "because it was free". If I hadn't come across it when I did I would have installed exactly what I am suggesting to you. I once owned a heating and refrigeration business and have had to dis-assemble and clean mini split systems that were so clogged with dirt that they were totally ineffective, and it sometimes took a couple of hours to get them clean again. A good filter, changed often, is much cheaper that my service calls were.

Charley

Old post but a good one. I live in the desert and use an AC, so humidity isn't the issue for me. My main shop is in a 12x24 shed, R38 insulated ceiling, white roofing. Also, between the insulation and outside wall, I put in radiant barrier, aluminum bubble wrap. In my garage, just the barrier cut the heat transmission by 35 degrees. The shed-shop walls are only R13, but with the barrier, the temp is kept cool with intermittent AC. It stays cool even on hot days for many hours if I keep the door closed.

Air filtration. I suggest you buy one or two WEN brand hanging units (pix), which I bought for just a bit over $100 each on sale. It has exactly the same hp and uses the exact same filters as the JET, which is 3 times the price. It has a timer so you can set filtration speed and time up to 4 hours. Even has a remote control.

For comparison, here's the Grizzly unit...


For rust protection, when I first set up the shed-shop, I had a swamp cooler in it, so rust became an issue. So I did some research and started using a product called Boeshield T9, which is a Boeing aircraft protectant. I have reapplied it once. It does not affect finish, and works incredibly well.

Garage Door. I insulated mine in about 4 hours. First cut and laid in a layer of radiant barrier, then cut and laid in a layer of insulating foam, then another layer of barrier. Then carefully cleaned all the steel door parts involved, then sealed the insulation in with aluminum duct tape. Don't skip the cleaning. Did this a few years ago and the tape is still holding just fine. If I were doing it again I'd consider putting in self adhesive strips between the horizontal door segments. The biggest issue is heat leaking in around the door seals on the side and top.

We had the garage worked on a couple of years ago, Radiant barrier under the roof's sheeting , then R38, a fan that vents heat out, plus "bird holes" with some plastic things that allow air to come in through the screened bird holes. Trapped air just pumps heat in. The crawl through hatch is also insulated, but needed to service the fan. They then applied fire retardent sheetrock to the ceiling. Heat does not come in through the ceiling at all.

We found that the walls were not insulated, so we cut holes in the sheetrock, above and below the fire stops, and had R13 blown in. Unfortunately, we go in and out and have to raise the door, but it never gets as hot in there as it did before we insulated.

If I lived in Florida, given how muggy it has been on my summer visits, and wanted to store expensive wood, I'd consider building a small enclosure to store it and place a dehumidifier in there. I'd NEVER open that door if I didn't need any wood. I might put a door with a window for access so I could check a humidity gauge of some sort inside. A search just now turned up humidity sensor switches for from 15 bucks and up. Plug the dehumidifier in this to regulate on off time in that storage chamber. [New Generation] Humidity Sensor Switch, Ortis in-Wall Bathroom Fan Automated Control Switch, Air Moisture Detection, Neutral Wire Required, White, 120V/220V: Amazon.com: Industrial & Scientific

Have to admit, Florida and East Coast humidity is a major reason I live in the desert out West. I don't think my breathing issues could stand up to that sweaty air.

Just sharing this so if anyone is thinking about this process, they can follow the amazingly good suggestions in this string.