AC- window unit or mini split?

[Rob Price]

We just moved into a house with a detached two car garage that I get to call home for my shop. It's easily double the space I used to have. I went ahead and had the place insulated (R-19) before I set everything up, I figured I'd never want to go back and take it all off the walls to insulate in the future. Now my question is about AC. It's definitely much cooler with the insulation, but we have hot humid summers here. It's still probably 80 degrees or more in there, and I sweat. A lot. All over everything. I'm drinking tons of fluids trying to keep up. I guess I was spoiled a bit with our cooled/heated basement before.

There is an upstairs 'attic' area with two windows. It's all insulated, with polyvents in the roofline. I can add a 14,000 BTU window unit (Wynter or Honeywell on Amazon) for around $500-600. A buddy of mine put a mini split in his garage but it cost him $2k. For half that I could go with two window units. I do see some mini splits on Amazon in the $700 range but I don't have any HVAC experience, vacuum pumps, etc so I would have to hire someone to install it for me. I'm going to get a quote, but wanted to see what you guys thought. One of the windows faces the back yard, and it's 20' off the ground (steep slope behind the garage) so I'm not terribly worried about the security of having a window open. We have a dog in the back yard, etc.

Is the mini split worth it? I imagine it's quieter.

[Ole Anderson]

Just think of the tools you could buy with the money saved if you went with the cheaper solution. And you are worried about noise in a shop?

[David Weaver]

To me, it would depend on how much you intend to run the units. If you're running them all the time in georgia, you might get the money back out of a mini split.

What I found, however, is that the authorized installers around here just about want to own you to put one in. I bought a mitsubishi unit through my contractor (at cost from a supply place that you can't buy directly from if you're general public) and his HVAC sub installed it, otherwise it would've cost me more than $4k for a mitsubishi unit with heat and cool, and as it was with me buying everything and paying the sub $750 to install it, it was $3k (just over $2k for both parts of the split unit and the line set, and another $200 to get an electrician to run a 220 line to it and install a whip disconnect).

I had trouble here finding someone who would install it otherwise, because most of the folks who install splits regularly are already working for an installer and don't want to get in trouble doing side jobs. It's more efficient than anything else I've ever seen, though - and will do the same cooling on 950 watts that most window units will do on 1500 - about 10 cents difference per hour here for every hour that it runs, or a little more because it has the ability to run at variable speed and cut its consumption a little more than the EER would suggest.

The mini splits that are $700 are probably only one half of the setup - you need both parts and a line set, and likely a dedicated 220 line with whatever breaker size the installation manual suggests.

[Al Launier]

Last year I purchased (2) 15.1K BTU Fridgidaire Window AC units, one for the 1st level (1800 sq. ft.), the other for the 2nd level (1700 sq. ft.). Fortunately I have an open concept house, plus each AC unit is in a window that is ideally located to service a large central part of each level. I was pleasant surprised at how effective these units were in cooling the house in 85-90°F summer temps that we occasionally have in southern NH. You might want to check this out http://www.bestbuy.com/site/frigidai...unit&cp=1&lp=9 to see if it interests you. I was also surprised to see that these operate on 115VAC.

[Rob Price]

I honestly get about one afternoon a week in the shop on a good week. So most of the time it's going to be set 85 or so if it's in the attic area, hoping to keep the shop area around 80 or so when I'm not there. Just enough to dehumidify a bit. I've run all the wiring myself, I put in a dedicated 20A line for AC. I think if I was out there every day I'd go ahead and put in a mini split, but maybe for my occasional use the window unit is the way to go.

Edit: I just measured my back window. Only 18.5" wide. Limits the size of the window unit unless I cut a dedicated opening for it.

[Scott Brandstetter]

Hey Rob, couple thoughts on your situation. First of all, congrats on the larger work space, enjoy it. In regards to the question of whether a window unit or split duct, have you considered resale. I'm not sure what the space looks like and how a future buyer might look at it but could be a plus for split duct. And not that this is a lot of help but I happened to notice a split duct system at Costco the other day when walking out. Again, didn't stop to talk but since my brother is in the market, did notice. They do have some incredible deals at times. Good luck and keep us posted.

[Phil Thien]

You can get 12k-BTU units designed for casement windows which may fit your narrow window (depending on height):

http://www.amazon.com/Frigidaire-FRA...ir+conditioner

I'd probably just install a sleeve through the wall, though.

[John Huds0n]

Instead of installing window units in your attic area - have you thought about installing 'through-the-wall' units closer to where you will be working? You install a 'sleeve' in the wall and then the unit slides into the sleeve. You do not have to remove them during the winter and they are much more secure.

If you go to this link on Amazon you will see the units and the required sleeve
http://www.amazon.com/s/ref=nb_sb_no...he%20wall%20ac

With that being said, I just ordered a Mitsubishi Mr Slim from a place out of Illinois - eComfort.com. I plan on doing most of the install myself and then have a local certified hvac contractor come over and 'start it up' for around $300 to maintain the 5 year factory warranty

http://ecomfort.com/cooling-only-min...t-systems-147/

[Clay Crocker]

Rob,

I've had both. I cooled my previous garage shop with a window unit and I currently have a mini-split which I had installed in my shop this Spring. Yes, the window unit was noisy compared to my mini-split but I hardly noticed it when the dust collector and table saw were running. My current garage does not have any windows and for aesthetic reasons I did not wish to blast a hole through the wall to install window/wall unit, so the only real option in my situation was the mini-split. The up front cost of a mini-split is definitely much higher than a window unit; David's outline of the costs is spot on with what I found in my area. I looked into buying an inexpensive unit (~$2K) and installing it myself, buying a unit and having a pro install it (like David, finding someone willing to do this was problematic), but I finally decided to go with the easiest (for me) but most expensive option of a turn-key installation. Even with the turn-key approach I had trouble finding HVAC companies in my area willing to come out and give me a quote. Finally ended up going through The Home Depot who uses the local Aire Serv franchise to do all their HVAC installations in my area. I ended up getting a 24,000 BTU, Fujitsu with heat and cool. One thing that made the mini-split cost a little more palatable for me was the fact that HD had a 0% financing for 24 months deal at the time. I think in the long run the mini-split will cost less to run; although I'm not sure how long it will take to get a return on my investment. Which ever way you decide to go, I recommend that you take a close look at how much cooling load you have and get a unit properly sized to handle it. There are a lot of load calculators online that you can plug in values for your situation and get back an estimate of BTU's required. Good luck. Clay

[Norb Schmidt]

I'm in the northern Atlanta area and I added a mini-split to my basement workshop. It keeps the dust separate from the rest of the house, and was an economical alternative to adding HVAC (both heat and air) to the space. For me, if I sell the house, it likely becomes living space vs. a shop. I did the install myself - but left the connection of the line set and vacuum to my HVAC professional. The units come precharged, so there is very little to do other than cut off and flare the connector, then vacuum the lines prior to opening the valves. Wiring was simple - as the two units are wired together. Mine is a Mitsubishi - which has the fan run continously - some units are different. Mine is also a heat pump, which keeps the room climate controlled year round. Total cost was approximately $1,400.

I previously had a window unit in the shop and a kerosene heater for winter. I like my set up much better now. Electricity cost is negligible - maybe $20 a month for the shop. Noise and consistency is much improved over the space heater/window unit. Another consideration with the mini-split is that you should make a box to hold a particulate air filter for it - the screen that comes with the unit just doesn't seem robust enough for me in a shop environment.

My experience is that the installation isn't bad - it takes about a day to do it right, including making a concrete pad for the outside unit, running wire, drilling the hole, and connecting the line-set. It looks professional, keeps the windows functional, and the temperature/humidity is no longer an issue. Nothing rusts in my shop - and that's saying something in Georgia.

[Phil Thien]

Electricity cost is negligible - maybe $20 a month for the shop.

How much does it actually run? $20 seems very inexpensive.

[Michael Yadfar]

I don't know too much about these, I still got my own research, but for my shop I was considering a portable AC/ heater unit. This is just a standalone unit which vents to the window, but they're not badly priced. The one I was looking at was a 12,000 BTU unit, and it's only $500 at Home Depot. Like I said, I don't know much about these, but this is what I'm considering. My shop is also on 9'x16', so a lot of stuff is easily suitable

[John Stankus]

I installed a Mitsubishi Mr. Slim mini-split heat pump myself. It cost me a quarter to a third of the quotes from the AC shops here. Process was pretty straight forward.
The tasks are not that complicated to do. The task that took me the longest was getting the time to cast a concrete base for the outside unit, but you can buy premade pads.
The two critical tasks that I found were 1) use Nylog Blue sealant on the flare connections (it makes a big difference) and 2) make sure you pull a good vacuum before you release the charge from the compressor. It will take you much longer than you think to pump out all the moisture.

R410A is not an ozone depleter, so you can order it without an EPA certification. The systems are usually precharged for a specific lineset length (usually 25 ft) so you probably will not need any additional if you can locate the system within that distance.

John

[Scott T Smith]

I installed a Mitsubishi Mr. Slim mini-split heat pump myself. It cost me a quarter to a third of the quotes from the AC shops here. Process was pretty straight forward.
The tasks are not that complicated to do. The task that took me the longest was getting the time to cast a concrete base for the outside unit, but you can buy premade pads.
The two critical tasks that I found were 1) use Nylog Blue sealant on the flare connections (it makes a big difference) and 2) make sure you pull a good vacuum before you release the charge from the compressor. It will take you much longer than you think to pump out all the moisture.

R410A is not an ozone depleter, so you can order it without an EPA certification. The systems are usually precharged for a specific lineset length (usually 25 ft) so you probably will not need any additional if you can locate the system within that distance.

John

^^^ This. I did the same thing in my old shop; it worked great.

Mini-splits are extremely efficient - they usually have a SEER rating that is much higher than window units or traditional split systems; thus the opex is very low.

One thing that you have to ask yourself though is do you install a smaller unit and run it all the time (maximum amount of dehumidifying), or use a larger unit that you only use to cool it while you are in the shop.

In my old shop, I opted for a slightly smaller unit that would run more, and thus my lumber was kept around 8% MC.

Another choice is to not air condition the upstairs, and keep it warmer for wood storage.

[Norb Schmidt]

Its for a walk out basement, so two sides are under ground, so it's not beat by the sun like the rest of the house. That said, on hot days it runs about 20% of the time during daylight hours - and I'm cooling to about 77. Winter it runs less, and I heat to about 68, which keeps me working but not freezing. I found it remarkably efficient (20 seer).