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Forum topic by MJClark posted 05-28-2019 02:19 AM 1904 views 2 times favorited 23 replies Add to Favorites Watch
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MJClark

38 posts in 971 days


05-28-2019 02:19 AM

Topic tags/keywords: hvac garage home shop heat cold humid

I took a few months off as I acquired some new tools including a used 220v delta unisaw, dust collection system, and a few other things. Now that I have my shop layout situated, I am running into a much different issue. Heat and humidity. I living in the Raleigh NC area and it gets kind of warm.

Given that my shop is in a garage, I was wondering what others do for HVAC for their garage shops? Do you tie into the house HVAC, leave the door into the house open, ignore the climate and build, or do you do something else?


23 replies so far

View clin's profile

clin

1128 posts in 2083 days


#1 posted 05-28-2019 03:30 AM

DO NOT tie into the home HVAC system or open your house to the shop. This could spread fine saw dust throughout your house. This can present a health hazard.

I put a ductless mini-split in my shop. If you are unfamiliar with these, these are refrigerated air systems. They are split, which means the compressor is located outside and the evaporator/air handler (head) is mounted inside. A pair of refrigeration lines runs between them.

They are meant to condition large rooms or small areas of a house. Or in some case an entire apartment.

Quality mini-splits are EXTREMELY efficient. They use variable speed compressors. So instead of just off and full on, they can throttle down. This is much more efficient. They are designed to run 24/7. Or if you were a weekend warrior, you might turn it on Saturday morning, and run it through the weekend. It’s sort of like a car cruising on the highway (good gas mileage) rather than going full throttle to a stop and back up at every stop light.

How well this works depends on the ratio of shop to garage use. If it is more a shop that WAS a garage, then the mini-split is really good. If on the other hand, it is more a garage then a shop and the garage door is being opened often and a hot car rolled in, then nothing is going to work that great except some sort of grossly oversized system that can remove a lot of heat quickly.

A mini-split, being an AC unit, it will also remove humidity from the air. They are again very good at that. Many regular AC systems are way oversized for homes, and cool the house so quickly, they don’t have time to remove the humidity. Most mini-splits also run in reverse for heating in the winter.

There’s really no downside to them other than perhaps cost. You need to take some care to keep them from clogging with dust. But you should be keeping your shop air clean with a good DC and perhaps room air filter. In this way you shouldn’t need to clean the mini-split filter excessively often.

Other cooling options are to get a window type AC unit and fit it to a window if available or put it through a wall. I think there are also units specifically design for thru-wall mounting. A typical window AC unit won’t be nearly as efficient as a mini-split, but it would be much less expensive. So may still be the most economical choice if you don’t use it a lot.

Also, if not already, insulate the garage. First step in controller temperature is to insulate.

-- Clin

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John_

251 posts in 2793 days


#2 posted 05-28-2019 06:19 AM

Mini Split is the way to go if it is within your budget

I installed a 18k Mr Slim about 4 years ago and it is one of the best things I ever did. Purchased over the internet (eComfort) and installed everything myself – BUT, for warranty purposes, I had an authorized Mitsubishi dealer come out and start it up (Check lines for leaks, inspect everything and then release the freon)

Mini Splits are becoming very popular. There is a DIY brand – Mr Cool that Costco is now selling. I would really recommend looking at one of their units. (The lines are already pressurized – you just connect them and your good to go)

There are pretty good prices – Home Depot and other stores also carries the brand
https://www.costco.com/CatalogSearch?dept=All&keyword=mr+cool

PS – I had a ‘through the wall’ type AC before the Mr Slim and it was a waste of money

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CL810

4120 posts in 4075 days


#3 posted 05-28-2019 12:57 PM

Another vote for the split units. I installed a Mitsubishi and have had very good results. I think an underrated benefit is eliminating high humidity in your shop.

-- "The only limits to our realization of tomorrow will be our doubts of today." - FDR

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GR8HUNTER

8427 posts in 1799 days


#4 posted 05-28-2019 02:06 PM

my shop shed is in the woods under trees in constant shade so no need for cooling my fans do a great job … my problem is heating I am in process of insulating right now …. do you guys with split systems think it would benefit me to install one just for heating or just go another way them DIY mrcool seem rather cheap

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN :<))

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ibewjon

2431 posts in 3880 days


#5 posted 05-28-2019 02:07 PM

Mini split is a great option. Installed my LG 4 years ago, along with hour meter and kwh meter to monitor power usage. I can keep my shop, 16×22 x10’ ceiling cool and DRY for 25 cents a day. It is a 28 seer for AC, and I think 14 for heating, and works down to 10 below zero, which you will never see. As long as your dust collector does not vent outside, it will do the job cheaply for you. I got it from supply house ,com, many suppliers out there. It also has internet control, which is handy if away for extended periods.

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ScottM

756 posts in 3233 days


#6 posted 05-28-2019 03:22 PM

No one, that I saw, mentioned insulation. For the guys with mini splits, are your shops insulated?

View ibewjon's profile (online now)

ibewjon

2431 posts in 3880 days


#7 posted 05-28-2019 03:46 PM

Absolutely. I would never consider trying to heat or cool in Illinois without insulation. 6” fiberglass in the walls, 10” fiberglass in the ceiling. Also housewrap under the siding. Three outside walls, the fourth, downwind side, is against the unheated garage.

View bmerrill's profile

bmerrill

127 posts in 1160 days


#8 posted 05-28-2019 08:55 PM

Another vote for a mini split.

Live in eastern North Carolina.
Have a 2 ton Mitsubishi Mini-Split in an insulated 2 car attached garage/workshop to the home with an insulated 18’x7’ OHD. Garage is 680sf with 12’ ceilings and 2 tall windows.
Room above the garage is conditioned space.
The south and a portion of the east wall adjoin the house.
Garage also has a fridge and a separate freezer.
Unit is very efficient in heating and cooling the space.
If the system has been off for sometime it will take a while to bring everything in the space upto temperature.
Once everything is up to temperature, opening the door does let in cold or heat, but the air temperature recovers fairly quickly.

-- Woodworking, the transformation of nature to culture.

View bigJohninvegas's profile

bigJohninvegas

1006 posts in 2549 days


#9 posted 05-29-2019 04:00 AM

So I did a mini split last year and love it.
First off, I have a fully insulated, 3 car garage/workshop, about 600sqft. And I am in Las Vegas, Nv. My summer temps in the afternoon when I get most of my shop time range from around 100 to 115. And my only cooling was to open the door to the house and put a large fan to draw A/C air from the house. And like others said. I got saw dust in my home. And 80 seemed to be as cool as I could get.
As you can see from all the replies. Mini split seemed to be the way to go.
So three bids later form the pros, and they all came back at around 6k. Sticker shock!
That’s way out of my budget.
So I had already read about a DIY mini split units, And decided to go for it.
https://www.homedepot.com/p/MRCOOL-DIY-Enhanced-24-000-BTU-2-Ton-Ductless-Mini-Split-Air-Conditioner-and-Heat-Pump-208-230V-60Hz-DIY-24-HP-230AE/309068910

I chose this unit, and it was the same btu the pros wanted to sell me. It is a total DIY system, saying you can handle adding 220v on your own. I needed some minor help there, and had a electrician friend for asst.
I got mine through Home depot, delivered to the store for free. I figured if there was an issue, I would be taking it back to them and having a face to face transaction, vs a 1-800 good luck phone call.
So I have been holding off on a real review, wanted to get a full season on it. But I think I will get one done soon. My install was complete right at 7/4/18. And for the first month I would turn it on when I got home from work. Took about 45 min. to go from 85 down to 76. Then mid August I started leaving it on. Kept the shop a constant 77. To my surprise, my power bill went down about $15 that month. I can only assume working the main house A/C gave me a higher bill. As for winter, I only get a couple weeks a year, most years. The really need a heated shop. And this year a think I used the heat 3 times. worked great.
Todays price shows it around $1650, but I spent around 2k when you count all the extras. electrical, concrete pad, and line set conduit.
Only regret is not pulling the trigger 5 years earlier.
good luck

-- John

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CaptainKlutz

4456 posts in 2581 days


#10 posted 05-29-2019 05:33 AM

Grin and enjoy the outdoor weather is my preference, even when it’s 110F here in AZ.
When it gets too hot, go inside and do something else.
YMMV

+1 insulation before spending money on AC. If you can keep shop closed off from warmest weather, can open it up and work when it’s cooler. Plus need to spend 2X on up-sized mini-split unit and utilities without insulation.

+1 mini-split. Self installation is pretty simple with prefilled lines, as long as you can do the electrical.
If you live in place with neighborhood Nazi (HOA), many have limitations on installation location of condensing units (typically out of site, and not heard directly from neighbors back porch).

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

View Bill Berklich's profile

Bill Berklich

1179 posts in 1475 days


#11 posted 05-29-2019 10:44 AM

I like the Mini-Split idea and will probably adopt it in my next shop. While in Memphis TN, like you, I worked in the Garage (no basements there) and had to contend with heat and humidity. No A/C so just quit working in the dead of summer… I’m happy to be back in Michigan. Best of luck in you new digs!

-- Bill - Rochester MI

View Sawdust2012's profile

Sawdust2012

259 posts in 2799 days


#12 posted 05-29-2019 10:56 AM

Greensboro, NC here. 1.5 ton mini split in 550 sq ft garage. It does an amazing job, probably better than the 30 yr old central unit on the house. I had one shipped to the house from Alpine Air at a great price. I had to have it installed, but if you can do that, it’s absolutely the way to go. Sometimes I go out to watch the water drain out of the condensate drain tube! I sleep better knowing that my cast iron isn’t rusting! Mine has a heat pump also which makes the garage as comfortable as the house. Either insulate the door or buy an insulated door. Put a couple of WiFi speakers on the wall, and some Waylon Jennings on the iPhone, and the only reason to leave is to buy scotch!
https://www.alpinehomeair.com/viewcategory.cfm?categoryID=97

View OSU55's profile

OSU55

2795 posts in 3076 days


#13 posted 05-29-2019 12:24 PM

Won’t be without HVAC in my shop – just makes it so much more enjoyable. How you use the area is important, ie keep a constant temp and occasionally open the door, or just use the shop intermittently and want the temp to come up or down quickly. DO NOT tie into your home ac or leave doors open.

Intermittent use requires a much larger unit, and depending on the cycles can be more expensive to operate vs continuous temp control over the year. Insulation is less important for intermittent.

Continuous – insulate well, including garage door. Mini splits work very well, but there are potentially much cheaper options. I happened to have a window in my garage, and put a <$200 10k window unit in. With very good insulation it maintains about a 22 deg delta vs outside in a 675 ft2 area, and dehumidifies very well. Over sizing the ac does not dehumidify well. I can keep it warm with a small 120v 1500w heater in MO.

View rbrjr1's profile

rbrjr1

217 posts in 1292 days


#14 posted 05-29-2019 03:26 PM


Greensboro, NC here. 1.5 ton mini split in 550 sq ft garage. It does an amazing job, probably better than the 30 yr old central unit on the house. I had one shipped to the house from Alpine Air at a great price. I had to have it installed, but if you can do that, it’s absolutely the way to go. Sometimes I go out to watch the water drain out of the condensate drain tube! I sleep better knowing that my cast iron isn’t rusting! Mine has a heat pump also which makes the garage as comfortable as the house. Either insulate the door or buy an insulated door. Put a couple of WiFi speakers on the wall, and some Waylon Jennings on the iPhone, and the only reason to leave is to buy scotch!
https://www.alpinehomeair.com/viewcategory.cfm?categoryID=97

- Sawdust2012


I came here to post this.. Alpine Home Air has much better pricing than MR Cool for those of you on a budget.

-- only an idiot dismisses an intelligent statement because they dont know anything about the person delivering it.

View John_'s profile

John_

251 posts in 2793 days


#15 posted 05-30-2019 05:37 AM


Greensboro, NC here. 1.5 ton mini split in 550 sq ft garage. It does an amazing job, probably better than the 30 yr old central unit on the house. I had one shipped to the house from Alpine Air at a great price. I had to have it installed, but if you can do that, it’s absolutely the way to go. Sometimes I go out to watch the water drain out of the condensate drain tube! I sleep better knowing that my cast iron isn’t rusting! Mine has a heat pump also which makes the garage as comfortable as the house. Either insulate the door or buy an insulated door. Put a couple of WiFi speakers on the wall, and some Waylon Jennings on the iPhone, and the only reason to leave is to buy scotch!
https://www.alpinehomeair.com/viewcategory.cfm?categoryID=97

- Sawdust2012

I came here to post this.. Alpine Home Air has much better pricing than MR Cool for those of you on a budget.

- rbrjr1

If your looking for a Mr Cool unit – you probably want the ‘DYI” models that come with the precharged lines

And, Alpine Home Air may have decent prices, but Costco is still cheaper and you can’t beat their return policy or customer service

AlpineAir 1.5 ton DYI = $1,400
https://www.alpinehomeair.com/viewcategory.cfm?categoryID=319

Costco 1.5 Ton DYI = $1,300
https://www.costco.com/Mr-Cool-DIY-18K-BTU-Mini-Split-Heat-Pump-with-WIFI-Smart-Controller.product.100493414.html?langId=-1&krypto=dYz4fTilTKOfOLh0VyqkLEZzbSdi7tnLT8rtaT9zCxS5uEzj%2FOKoahcZr9qMloZHUTOxosmxj664uHV5oi6ZR%2F3z%2B9IF4ijPTifJAjK8By%2BH7lDuE3PR6JaEfqOIZoXix8VdHM4%2FOKc0deqqLyu1kZW6JEPpBw8iFiiIGg2XX49BsizwCvHZiYJVYOey4hZvEJFokhbNVyFQ6XQdv0N4VxdGvYHeI2A3MY%2BIQCnTyox8J%2FBGEjJ31474NSwxQ2ln7JHnr9vldiL1BYhaoBGPww%3D%3D

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