Controlling Temperature & Humidity

[Scott Cenicola]

I have a 20 x 24 2 car garage that I use as a dedicated wood shop. It is attached to the house and has 2 walls concrete block, garage door in the front and stud wall in the rear connecting to the house. I live in Tampa, so it's pretty hot all year long. My old central AC took a poop this summer and we had a to purchase a new unit. I can only assume that there was some type of leak in the ducting of the old unit, Previously, even in the summer my shop temp was manageable. It was hot, but I could still work in there. Now during the summer it was unbearable to be in there in the daytime. Another weird issue is the projects that I stain and finish won't fully dry now. They stay tacky for days and I have to bring them in the house to fully dry.

So, I am thinking about a few options and would love any and all advice. I plane to put insulation in the attic over the shop, as it is currently insulated. R30 between the rafters (any advice on this, or is it as simple as it seems?). I'm thinking that would help the temp. I just looked up this item this morning to control humidity http://wizzvent.com/ . I am wondering if anyone has used this or anything similar. Can I use just a simple dehumidifier and save some $$$! Phase 3 of the plan would be a portable ac from craiglists. I would love a minisplit, but it maybe out of my budget. I don't need 70', anything under 80' would be great.

Any and all suggestions would be much appreciated! Thanks in advance for your help.

[Lee Schierer]

Wizzvent looks like snake oil to me. It appears to be a fan with a humidistat. It is supposed to pull outside air into your space. If it is humid outside it will soon be humid inside. Other than bringing in some fresh air (I didn't see any air flow numbers) I fail to see why you would want to buy this.

Insulation will help keep the heat out, but once the garage is hot, it will also keep the heat in. If you want dehumidification, then you need an A/C unit or dehumidifier. The A/C unit will probably cost about the same to run as a dehimidifier but will also make your workplace cooler if it is installed in a window. POrtable units must also be vented outside to work properly.

[Duane Meadows]

I am in total agreement with Lee. If an exhaust fan with a humidistat is what you want, can be done much less expensively. Won't do much to control humidity, though. Heating alone will reduce humidity in the winter. That is why many people run humidifiers in their homes! In the summer, A/C or a dehumidifier will do the job.

[Randy Cohen]

It sounds like the old ac unit cooled the garage somewhat but the new one doesn't. is that right? i would fix that first.

[Scott Cenicola]

Although unintended, I guess it did. Sounds like an ac will cure both issues. Thanks to all.

Can anyone speak to the value of adding the R30 in the ceiling? Or seems pretty easy and I am planning on doing it myself. Any hints or advice?

[David Hawxhurst]

wear long sleeves when doing insulation.

[James Conrad]

Insulate the 2 cement block walls, add more in the ceiling, make sure your garage doors are insulated and sealed best you can and try a window AC unit.

[Mike Wilkins]

Only half of my shop is currently insulated (will remedy this soon). I have a humidity guage in the shop. With the door closed and the AC running in the summer, the humidity will noticeably drop several points in just a short time. Insulation and AC will remedy your problem, and make it bearable to work again.

[Bruce Lundgren]

Scott, I had the same issues regarding humidity and cooling here in S. Florida. I have an oversize 2 car garage but did have the ceiling insulated as well when we built. I added a Mitsubishi Mr Slim unit. It was pricey but well worth it. The garage door was not insulated and faces South and the heat really radiated from it. Because the door was designed for hurricane code the bracing made it easier to insulate with ridged foam from Home Depot which I cut and adhered with 3M foam spray. What a huge difference! The garage door is also well sealed. The A/C unit now cools it down in about 30 minutes. I don't have a window to install a wall A/C but probably would have gone that route had it been practical. Unlike up North where the cement block would need to be insulated, I've not found it to be necessary. Hope this helps.
Bruce

[Bill George]

Bruce it sounds like you did it the right way, insulation and a good AC unit. The important thing to remember is when it comes to sizing an AC unit bigger is not better. A slightly under-sized or correctly sized unit removes a lot more humidity than one that is to large. You want the unit to run at least 50% of the time, more run time is better for humidity control.

Commercial units for humidity control in large supermarket for instance, will tie the humidistat or sensor to the AC unit control system and run it. If the space then gets to cold they use either a reheat system tied to the AC condenser circuit (free) or turn on a reheat system using gas or electric heat.

I have a window unit in my insulated garage/shop works great.

[Scott Cenicola]

Thanks to all for your ideas. I just picked up a portable 14000 btu ac on cl for 125, so I'm pretty excited. Its actually pretty cold here in Tampa (52, lol) so I'll only be dehumidifing for now. I am gonna insulate the ceiling over Christmas break, while all the decorations are out of the attic. After that, just have to tackle insulating the door as Bruce suggested, and hopefully the shop will be workable year round. Thanks to all for your advice!

[Alan Lightstone]

Scott:

I chose the split AC unit approach in Tampa for my 2 car garage workshop. Door was already insulated, and I later added blown insulation to the attic.

Shop stays cool whenever I want it to be, but humidity under control.

Your portable will probably work reasonably well. I use a few as emergency AC in my home, as our AC always picks the worst time to need repairs.

I tried and returned a dehumidifier. It's a losing battle to handle humidity that way in Tampa.

So, basically having tried all you are suggesting in your same climate, you should be just fine.