Air Conditioning the Shop

In Arizona, our Summer days regularly reach 110 F and a closed garage can easily exceed 120F. When I was just making furniture for clients, I used to tough it out and deal with it. But as soon as I started making podcasts for a living, things changed. No one wants to see me sweating profusely and its difficult to smile and be jovial when you are literally working in Dante’s Inferno. So even though this is supposed to be a temporary shop situation, summer is already here and I need air conditioning! I decided I would share my experience with you just in case you were interested in installing A/C in your shop. Keep in mind, technology and pricing will certainly be dependent on your region.

Prior to contacting any installers, I did my research. In fact, I’ve been researching this for quite some time now knowing that this day just might come. I have also talked with many other woodworkers about efficient A/C for the shop. My buddy Vic in particular was very helpful in getting me the info I needed. My final decision was to install a ductless mini-split heat pump. Here are a few of my reasons: better efficiency, easy retro-fit, less intrusive installation, whisper quiet (important for filming), and remote control. Armed with this information, all I needed was someone to do the installation!

The first thing I did was call several A/C contractors (something we have no shortage of in Phoenix). I picked the top-rated one via a Google search, and three from the yellow pages. Only three responded. So here’s how it went down.

A/C Contractor #1:

I explained what my needs were and that I wanted the ductless heat pump. He gently began to push me in the direction of a more traditional system with an air handler and ductwork. He said that the only reason to go for the ductless system is if you really needed things to be quiet (judging by all the tools, it was obvious to him that noise wasn’t an issue for me). I then revealed that I make videos for a living, and noise was indeed a major issue. He then acted as if he never mentioned noise, and continued to lay out the strategy for the ductwork. And not that it is vital to this conversation, but he also made the mistake of insulting the quality of my dust collection ductwork. What an A-hole. Anyway, it became clear that no matter what I said, I wasn’t going to get an estimate on the unit I wanted. In fact, he completely ignored my request for two estimates: one traditional and one for the mini split.
Estimate Details: 13 SEER 2.5 Ton Heat Pump and Air Handler (York). Electrical work included in price. Plan includes ceiling-mounted air handler to minimize effect on shop space. Total price with tax: $5788

A/C Contractor #2:

This visit was much the same as the first. Although a much nicer guy, it was clear that he didn’t want to install the mini-split. He did, however, suggest a higher SEER unit so that we would be eligible for a federal and local rebate. This rebate would give us nearly $2000 in savings.
Estimate Details: 15 SEER 3 Ton Heat Pump (Amana). Electrical work NOT included in price. Plan includes floor-mounted air-handler which would require me making room for it. Total price with tax: $6100

Interesting so far. The second setup with the better A/C unit is only a few hundred dollars more. But I had to consider the extra cost of running the electric. Even then, with the rebates, it would still wind up significantly cheaper than the first quote and I would have a more efficient system. Major downside is the fact that its a floor-mounted air-handler. At this juncture, I was losing sight of the key point: neither one of these were the system I actually wanted!!

A/C Contractor #3:

I described my needs and expressed my desire for a ductless mini-split. The whole time he was nodding in agreement and said that he thinks its the perfect system for my situation. He immediately began developing a strategy for where the blower would be mounted and how we can run the lines with the least visibility on the outside of the house. We also had a conversation about my other two estimates and why they insisted on a traditional ducted system. This stuff may be obvious to some of you with experience, but it was very revealing to me. He said that most of the local A/C guys have so much time, money, and training invested in conventional sheet-metal ductwork installations, that its just not profitable for them to install a ductless system. In order for them to see any return at all, they need to do a full job and a full day’s worth of work.

Estimate Details: 16 SEER 2.5 Ton Ductless Mini-Split (LG). Electrical work NOT included. Total Price With Tax: $5134

So finally I feel good about this. I am getting the A/C unit I want and if we ever build a new stand-alone shop, its something that can be transferred to the new space. The unit will be super quiet and very efficient. Maybe I’ll feel a little less guilty running it during the hottest days of the summer! Here are a few pics of the installation.

Note: The intention of this post is not to give advice, but to simply share my experience. I am sure there are many different opinions on what is right for a situation like this. But if you are considering A/C for your shop, its nice to know what someone else’s experience was like so that you are prepared going into it.

Update (6/11/10) – Everything is completely hooked up and I did a test run. Its only 95 outside today, so the new AC cooled the shop down to the 70’s in no time. The real test will be when the 110-115 days come rolling around. I’ll keep you posted.

Category: The Shop


  1. Jeremy June 3, 2010

    “…its difficult to smile and be jovial when you are literally working in Dante?s Inferno.”
    Ever heard David Cross do his rant on misuse of the word “literally”? it’s a good one and this reminded me of it. :)

    As much as the first contractor sounded condescending and you did find one that wants to do it your way, or, it would seem from the pictures… DID it your way, I do find those ductless units to be less effective than traditional systems in a few the cases I’ve dealt with them. One of the biggest problems is usually that the source is only in one part of the room, in a large space this can create a problem. Another issue I have seen is that the thermostat is often located very close to the unit, which tricks it into thinking the whole room is cool when really just the area right near the unit is. My parents have one like this in a very large room in their house and because it is unthinkable for my dad to set a thermostat lower than 70 degrees, the other 3/4 of the room are more like 76 degrees, or essentially, not air conditioned. Putting the fan on the highest setting helps distribute the air better of course, but will be louder. Speaking of which, it is not my experience that the ductless units are quieter than traditional ducted units, usually louder, I’d say because the fan is right there. Now, if you are talking about the air handler being located in the space that is obviously a different ballgame.

    I am not an HVAC contractor nor am I trying to be argumentative, just giving a different perspective from my experience with these units.


  2. Nice write up. This will help if I ever get a bigger shop.

  3. Richard June 3, 2010

    When I was having my shop built I asked for the same type of unit often seen in motel rooms. Not sure of the name.
    It works well and is quiet. Keeps the shop warm and cool here in Arkansas.
    Sits on the wall at floor level in a corner out of the way.

  4. Dan June 3, 2010

    WOW. I have a 20×24 freestanding workshop. Of course it isn’t quite so bad here in Indiana, I put in a 10,500 btu window unit. But instead of mounting it in a window, I did a through-the-wall install. Total cost $200. I installed it myself. I’m sure yours is nicer though!

    • Mattias in Durham, NC June 4, 2010

      I did the same thing. North Carolina, 12×16, R13 in walls and ceiling, R4 in floor, about 5,000 BTU. Works great, even on the hottest days, and when running tools.

      One thing I can recommend if going this route–especially if you are a weekend warrior–is to look for a unit that turns itself back on after a power outage. Otherwise you might find that there was a power blip several days earlier and your shop is at a steady 85F.

      • Bill Wheaton August 1, 2010

        I am concerned about rusting my tools and adversely affecting my lumber.
        I’m sizing of a window AC unit (thru the wall) for an 11 x 19 stand-alone shed. It’s got no windows, partially shaded afternoon sun. Atlanta GA is 80-90 degrees in the summer with 90-60% humidity. It has R13 insulation and rests on a concrete pad.

        The air conditioner calculators say that need 2800BTU AC, but they don’t make units that small, so the lowest size is 5000. But they always warn about using oversized units because it may not dehumidify it very well.

        So, what is peoples experience for a shop this size is 5000 to small? too big? should I opt for 12k btu?

  5. Vic June 3, 2010

    I’m glad it worked out for you, Mark. Check with your accountant and the contractor if this unit qualifies toward the $1500 credit.
    As you know, I have these in my house and love them. The sensing unit is actually in interior unit. If positioned correctly and using the oscillating feature, available on most DHPs, air migration is excellent. My office is heated and cooled passively from the greatroom unit and is only ever 2 to 3 degrees warmer or cooler than at the unit. The correct size unit makes all the difference, so be sure to deal with someone that knows what they are doing.

  6. Marc – Thanks for the write-up. I have been thinking about installing AC as well – it would be more for the humidity then the temperature. What’s the upkeep on the unit? Will the sawdust affect it at all?


    • Vic June 3, 2010

      Jonathon, any heat pump or A/C unit will be extremely sensitive to the fins getting too dirty or clogged, as this is the conduit for transferring/dissipating the heat. They are very much like the fins on a car’s radiator. These units have washable filter that do a very good job of protecting the interior unit’s fins. It is still up to the owner to clean the filters when needed.

  7. TJ71 June 3, 2010

    Cooling only one room? and people wanted you to put in a ducted system? wtf? anyway i hope the unit you bought is oscillating. any more than one room and insulated ducted is better.

    • Vic June 3, 2010

      Actually according to the pilot programs being run, These units do very well, even in multiple head applications. The inverter driven compressor units (which Marc got) are much more efficient. They are very quiet (about the same noise as the refrigerator cycling) and there is no heat loss from inappropriately placed or leaking ductwork. The units being sold in Scandinavian countries are functional down to -17 degrees F. My own unit did fine on it’s own down to just about 0 degrees, before I kicked on my old ducted gas furnace. You DO need back up heat in colder climates.

  8. Not sure on building codes in AZ, but wondering if the first 2 were trying to tie it into your existing home system. In Ontario, you are not allowed to tie house ducting into the garage as CO gas will get into the house and that’s not good!

    My point being that anyone thinking of getting AC in their garage shop should check their codes first. Even if you plan on never using it as a garage again, it can affect your ability to sell if you decide to move. Also, the gov’t can tell you to rip it out if it doesn’t meet code!

  9. kentuckybill June 3, 2010

    Glad you got what you wanted, as you should.
    I have a question for any HVAC guys out there. My forced gas heater and ac is in a room attached to my garage. Can I add a duct from that room to the garage? I have heard you cant get it done on new construction because of permitting. Just wondering what would be the reasons you can or cant.
    Thanks, Bill

    • Vic June 3, 2010

      Bill…many times the reason something is code is based on one persons interpretation of code and that code may not be base on common sense. But, that said, it’s STILL code.

    • I would be wary of connecting house ducting to the garage. See my previous comment for further info

        thewoodwhisperer June 3, 2010

        I can say that none of these contractors were talking about tying the system into the house system. It was all stand-alone.

  10. MarkinPhoenix June 3, 2010

    Hi Marc, You are probably already ahead of me on this one, but, most of our homes out here don?t have insulation in the attic over the garage. Might want to poke your head up there and check??we don?t want you to melt (or burn out your new AC unit). It supposed to be 110 by Sunday out here

      thewoodwhisperer June 3, 2010

      OH yes. We already had cellulose insulation blown into the walls and above the garage space. For about $100 more, they blew a couple more inches in over the rest of the house. :) Being a bit of a penny pincher when it comes to air conditioning, it would drive me nuts turning on the AC in an uninsulated garage space.

  11. Gary June 3, 2010

    Great setup, man! One day this is the type of unit I’ll get in my shop. I did a portable Sharp unit last season on a budget. It never truly “cools” my shop, but it does take the brutal FL humidity out of play, and make it much more pleasant to work. These mini-splits are fantastic!

  12. Dan Drabek June 3, 2010

    Another alternative would be to move to Santa Cruz, CA.
    Our summer days are generally in the ’70’s with winter days usually in the high ’50’s. We don’t have air conditioners in Santa Cruz. For the handful of warm days we have a little fan.
    Sorry about that. :->


  13. Sounds like you had a typical (crappy) contractor experience, glad you found a good one.

    Do you get the rebate with the system you want?

      thewoodwhisperer June 3, 2010

      Still looking into the rebate. Not sure if it applies to this type of system.

      • Shawn Nichols June 7, 2010


        It should qualify under heat pumps since it’s over 15 SEER

        You’ll want to check and make sure but that’s the sight I used when I had a whole HVAC system installed last year. I got the federal credit.

        Also, look into state and local credits. I got another $400 from my power company.

        Stay cool.

  14. Vic June 3, 2010

    So, did you get a heatpump or just an A/C unit? Also, did you only get one interior unit and what is the btu rating on it? I’d have thought you’d have two interior units with a 2.5 ton. Just curious.

      thewoodwhisperer June 3, 2010

      Its a heat pump and I believe its 30,000 BTU. We talked about possibly getting two interior units and he felt that I would only need one. But in the new shop (if and when that dream happens, we would add another interior blower.

  15. We have the same brand and type of unit in the server room at work. It has made it bearable to be at the workbenches during the summer months.

    I’m probably going to be installing some type of A/C in my garage shop also because the heat and humidity here in NC shut down my woodworking over a month ago. No DIY salt-treatment for me.

  16. Mike Mathews June 4, 2010

    I put a unit similar to what you have in my 950 square foot shop. I is a Mitsubishi and works great. I didn’t want duct work that would collect dust.

  17. Adam Dixon June 4, 2010

    Not sure if I missed it, but which of them was the Google top choice? Or was he the one that didn’t even call back?

      thewoodwhisperer June 4, 2010

      I do believe it was the one that didn’t call back, lol.

  18. Steven Madden June 4, 2010

    Hi Marc,

    This is just a question, not a criticism. Why did you settle a split unit and not just go with a window unit? I also live in a desert and installed a window unit through the wall (25,000BTU Frigidaire) and it works quite nicely. Just wondering what you found in your research that turned you away from the window units.

    You know, as I was typing this, I realized that it was probably the noise factor. But just in case it was something else, I will post anyway.


      thewoodwhisperer June 4, 2010

      A few reasons. Noise, power, efficiency, and perhaps the most important factor of all, the HOA. My only windows in the garage are three front-facing non-functional windows. So even if the HOA would allow such a thing (which they wouldn’t), it would have require modification of the window to get it installed. Also, I plan on re-using this system in my fabled “new shop”, so I need to keep that in mind as well.

      • Steven Madden June 4, 2010

        Thanks Marc,

        One more question. I am interested in insulating my garage as you described in your reply to MarkinPhoenix. Would you describe how you went about doing that or point me to where you have already described it? How much did it cost? Did they have to drill holes in your walls? What “R” rating do you have up above, in the walls, etc.

        Thanks again,


        • Vic June 4, 2010


          There are many good resources on the net to obtain the minimum R-Value requirements for your region. Check with your utility for possible rebates and they should be able to provide a list of qualified installers, who would perform the air sealing which is just as critical to heat transfer, if not more. Feel free to pm me if you have questions on energy efficiency. It’s my day job.

          thewoodwhisperer June 4, 2010

          Hey Steve. Can’t recall the R value, but they blew the same mat that we have over the rest of the house. The walls did require holes in each cavity. Cost was reasonable but I don’t recall the exact number.

        • tpal June 7, 2010

          My garage/shop is not insulated here in Austin, TX and was wonder what price range to expect for insulation. Walls are brick/air/sheetrock. Nothing but rafters and deep storage above. 2.5 car garage.


        • Vic June 8, 2010

          tpal, The pricing will vary a great deal from area to area, depending much on the local economy (are the contractor’s hungry in your area?). But, as far blowing in, I’d consult your local utility for incentive first and advice on whether cellulose is a good choice in your area over loose fill fiberglass. It is a better insulator, but can cause problems in areas of higher humidity without proper moisture barriers. You can easily blow in from the sheetrock side. I much prefer blowing walls from the interior rather than the exterior anyway, because it’s much easier to seamlessly patch drywall or plaster than it is any of the exterior materials.

    • Vic June 4, 2010

      Steve, The big advantage in the ductless mini split is in models that employ the inverter driven compressor technology. This is what dramatically increases the efficiencies of these units. The installation of a regular heat pump without this technology requires fairly precise sizing to obtain the rated efficiencies. When using the inverter driven technology, a unit’s efficiency can actually be increased by oversizing the system.

  19. Tomfoolery June 4, 2010

    I have installed a split-system (mr. slim/mitsubishi) in my shop with another head in a guest room. In Florida we deal with humidity as well as heat and it handles both like a champ!

    I also added a whole-room dust cleaner and it cycles the air enough that the whole room stays cool – without it there may be a temp difference from the unit to the opposite wall.

    Have fun making wood-dust!

  20. Charles Green June 4, 2010

    I put a mini split in two years ago. While I do love it, I have had some dust issues. When it gets too dirty it quits blowing cold air. Also, I’ve had the water drainage line clog twice that forced some water in the shop. No big deal as I had nothing underneath the unit but I have to be careful not to leave anything there as I leave the A/c on a lot of times when I am not in there to keep it cool.

  21. Frank Kovach June 4, 2010

    I have learned more in the past five minutes reading this blog and comments than in my entire life up to this point about HVAC. By inference and direct information. Thanks, everybody. I can say that this…mini split? stuff works pretty well, even in spaces with no air circulation and, shall we say, an ENORMOUS dust problem. For about six months back in 2008, I lived in between giant containers of dirt, faced with OSB, on three sides, and more dirt on top about two feet thick. The fourth side, which was a simple 2×4 framed wall with more OSB had the door and A/C unit mounted on it. No windows. Sandstorms were frequent occurrences. As long as you remembered that you had to clean your system, which we did once a week whether it needed it or not we were kept pretty comfortable. Even the mice liked it.

  22. Steve Westbrook June 5, 2010

    Out here in Kuwait (deployed) we use the split systems for our offices which are basically rectangular trailers. Works extremely well even in (so far) 120+ degree weather in extreme dust conditions (dust storms). To maintain the condensor coils and keep them from getting too dusty, the maintainers spray them down with a bleach solution every month. That should help keep them nice and efficient.

  23. Danny Hellyar June 5, 2010

    Wow, couldn’t help but chime in on this one. I as well have a stand alone 600 square ft shop in my back yard . And living here in So. Cal, air conditioning was a must. I bought a 18,000 BTU, through the wall unit, at a cost of about $400 and it works wonderfully well. It’s mounted high on the wall so as not to take up my valuable wall space for hanging jigs and fixtures. But then my walls are 10 Ft high. How many thousands did you spend again on your contracted system? Ouch! I guess since most of your tools are gifted you can justify spending that much on AC.

      thewoodwhisperer June 5, 2010

      Well last time i checked, a SoCal summer doesnt exactly compare to Phoenix. This is also not a stand alone space. Its a standard 3-car garage with two large garage doors facing west. That means the afternoon sun will punish one entire side of the shop, and it happens to be the side with the most air leaks. Also, I cant really install a window unit in my shop due to HOA restrictions and the fact that I have no functional windows. Furthermore, the system needs to run almost daily for the entire summer season. Efficiency is a major factor. So I can justify it not because I have money to burn, but because I run a business out of my shop and it simply makes sense. A small wall system would be costly in the long run because of its inefficiency and would likely provide a loud and uncomfortable space for me to work in.

      • Germain June 6, 2010

        I understand the concern about efficiency. Even if you had HOA permission and installed a large window unit in the wall, it probably would have burned out the bearings in your electric meter trying to keep the shop cool.

        I grew up in SoCal and lived in Phoenix for several years. Cooling a space when the outside temp is 115 and the Arizona sun is beating on the roof and walls is a whole different ball game than cooling a space in 89 degree SoCal.

    • TWWMom June 7, 2010

      Wow, how rude!

      • Vic June 8, 2010

        You go, Mom!

  24. Lori June 5, 2010

    All this info is great. I live in Tucson, which is much cooler then Phoenix. We probably average 105 degrees as opposed to your 110.
    I would love to do this mini split system or any a/c but I still have to use my shop as a garage.
    I guess I am looking for opinions on whether it is worth cooling or am I just throwing money out the wind…garage door?

    • Vic June 5, 2010

      Lori, the answer to that question is dependent on how well insulated your garage is and more importantly how well sealed it is. Doors and windows are evaluated for energy efficiency with U-Value which is the inverse of R-Value. R-Value is the thermal resistance of a single component (ex. batt insulation within a wall) and U-Value is the efficiency value of a component or system. But, basically, if your doors have a U-Value of .25, then they have an effective R-Value of 4 or the inverse of 1/4. Garage doors also do not typically seal well, especially on windy days. So, it comes down to how much is shop time worth to you. If the value is enough, then look into a ductless heat pump system. The system, if installed by a good contractor, will be sized to compensate for the inadequacy of the space.

  25. Ron June 5, 2010

    Last fall I had a whole house high efficiency heat pump (3 ton unit) with a high efficiency backup furnace installed for about $9000 here in Seattle.

    The kicker is the unit I purchased qualified for a $1500 fed tax credit. The difference in price for a non- qualifying unit and the qualifying unit was $300 basically by upgrading the equipment to high efficiency netted me $1200.

    My total utility bills (gas & electric) dropped 37%. My payback time just from this saving without any increases to the rates is 9 years.

    By the way my estimates ranged from $6500 to $17,000. I picked the middle of the road price with a reputable contractor. All of the low ball bids came from contractors with less than year in business. All of high quotes came from contractors willing to finance.

    Good luck,

  26. steve June 5, 2010

    Marc, I live just to the north of you here in Utah, and while our summers aren’t has hot as yours, we still have several days of 100+ weather. Our climate is also very dry, which means that evaporative coolers can been used here. Do you think the small amount of moisture they put into the air would have an adverse affect on the wood? They are inexpensive to install, and the cost to run them is also quite a bit less than the alternatives.

  27. Jason June 6, 2010

    So? How does the shop feel now with the new a/c installed??

      thewoodwhisperer June 6, 2010

      Feels pretty much the same. Electrician won’t be here until Thursday. :)

  28. Jason June 6, 2010

    Oops. Must have missed the part about the electrician. Glad to see that your installer mounted the blower unit high on the wall. This is critical because heat pools near the ceiling and you want those heat BTU’s to get dumped outside where they belong!

  29. Frank Kovach June 6, 2010

    Well, Marc, I think we all want to hear, now that it’s past Thursday, how well the new system is working. I have a stand alone garage that came with the house, one of the perks, in my opinion, and I have been thinking ever since buying this place how well it would function as a dedicated work shop. Living in eastern NC we have humidity as well as heat, an AC unit of some sort would be a must. So…..cooler now?

    • Vic June 6, 2010

      See my response to Lori from earlier in the thread. But, one thing nice about the DHP system I bought is the dehumidification setting without the cooling, which would come in handy for your situation in the “shoulder months”.

  30. jHop June 6, 2010

    While I noticed you had the blow in insulation installed, you did not mention the garage doors. Did you have those upgraded to the insulated versions (as your previous house was), or were they already installed?

    I haven’t had the pleasure of dealing with any HOA, but I have heard some real horror stories. Glad to hear you were able to find a solution that did not bring you to conflict with them.

    Being in the Great Lakes area does have some tough weather moments. Typically August will bring heat ranges almost near your summer levels (maybe 110 – 115 max, in direct heat) but nothing like what you deal with on a regular basis in AZ. What really mucks us up is the humidity. Especially near larger lakes, I’d think dehumidifiers would be more effective than AC. But I’m not an HVAC guy.

    as an aside, I recently have discovered I’m not allowed to put WoodTalk Online onto my Shuffle: I tend to actually listen to it at work, which has caused me to decrease productivity… Fortunately I have all week to get caught up on all those back episodes…

      thewoodwhisperer June 7, 2010

      Hey man. The garage doors were replaced a few months ago, very similar to what we did in the old shop.

      lol sorry about WTO :)

  31. Will June 7, 2010

    A couple notes for those considering mini-splits:

    If you are only having to punch through one wall in order to connect the indoor and outddor units, they are EXTREMELY easy to install yourself…most even come pre-charged with refrigerant and with pre-flared linesets, although it is a good idea to have an AC guy suck the system down (for say $150) if you don’t have a vacuum pump handy (most of us don’t!).

    There is a big price jump between 24k btu units and larger units…high-quality (Sanyo, LG, Mitsubishi) 24k heat pumps (inverter technology) can be purchased online with freight for a hair over $2k, including the lineset. 30k btu units are upwards of $3500.

    I have heard many examples of absolutely ridiculous quotes being given by AC contractors on mini-splits, usually either because their whole intelligence around bidding systems is based on “conventional” HVAC, and/or they simply refuse to acknowlege and accept new, and in many ways superior, technology. (Much the same as the copper vs. PEX acceptance issues in the plumbing industry). IMO, mini-splits are the way to go in applications where the aesthetic of the system is not a major concern PLUS they are easily installed by a reasonably competent DIYer (municipal permitting issues excluded).

  32. R Furbee June 7, 2010

    I’ve been considering a package unit (no not that). It’s a combination air handler and heat pump that all sits outside. Duct work fits through the wall. It’s completely DIY. How are split systems DIY?

    • Vic June 7, 2010

      Furbee, it’s like Will was saying. You can buy units from place like You buy all the components and the installation is pretty straight forward. I’d say it’s a 7 on a scale of 1 to 10 on a DIY scale. Doing the connections of the flared line-sets and the deep vacuum on the system are the only things for which I would absolutely suggest you hire a professional. These use a refrigerant called R410 that LOVES moisture and if the flared connections are not tightened to the correct torque, they will leak and the deep vacuum is necessary for the system to run at peak efficiency. It wouldn’t make sense to buy the most efficient system you can get and not install it to perform to it’s specifications.

  33. Neil Capper June 7, 2010

    This may a bit backwards, but my air handler is in my garage shop, and I just opened the vent on the main shaft so it expels some of the air into the garage. It’s not as cool as the house, but it has kept the garage at about 75 F so far this summer, even when the outside is up into the 90’s.

    • Vic June 8, 2010

      Neil, while this is not ideal. It’s not a huge problem if you match the amount of supply air with return air from your garage. If you don’t, you can possibly depressurize your living area at the least, driving your bills up and at the worst, killing yourself if your have combustion appliances. The depressurization can cause back drafting and bring carbon monoxide into your living space. If you do have combustion appliances in your house, I strongly suggest you purchase good quality CO detectors and place them near the appliances and one in each bedroom. Even though the gas companies add scent to the gas, a slow leak will often be undetectable until it has killed you.

  34. Maybe its unique to my experience, but I find that working with individual contractors results in them pushing either the thing they want to do most or the thing they think will make them the most proud. I don’t know that the first 2 contractors were really pushing the ductwork installs because that’s what they know the best. Or maybe, that’s the only thing they know. Either way, you need air in there!

  35. Unfortunately it is hard to trust contractors due to the fact that most people have either had a bad experience or know someone who has. The only way to protect yourself is to study up on your project ahead of time which often makes you more knowledgeable than the contractor. Just like everything else these days ? question everything and do not blindly trust your contractor, doctor, salesperson, etc. They are primarily concerned about themselves; not you.

  36. Dan June 24, 2010

    I’m a little late to this conversation but I was wondering if an evaporative cooler would be a good economical solution for a wood shop in Phoenix. I figure since there’s low humidity it would not only cool a garage but help keep the wood from getting too dry while purging airborne particles from my shop.

      thewoodwhisperer June 24, 2010

      Evaporative coolers do work for a good part of the summer. But eventually, they stop working when the humidity goes up a little. And frankly, a swamp cooled room is never as comfortable to me as an air-conditioned room. but if you don’t mind the feeling and it keeps you comfortable, definitely a cheaper way to go in drier climates.

  37. Dave Morrison July 13, 2010

    The information supplied about Air Conditioning a shop is something that is usually not covered in woodworking magazines/sites/blogs etc. And I would like to thank Marc for covering this topic
    I have been in the DFW area since 1986 ( yes we get those 100-110 days, though not like in PHX ) and through all those years I have seen very little on AC’s and shops.
    I can heat my shop with a couple of ceramic heaters on those cold days I’m out there. Or just not go out that day. Mine is a hobby not a business. A little trick I learned by chance. I take the car out to HD or Lowes for parts. Return and park the car in it’s normal place ( the center position of the garage, the single side bay is the shop ). Lift the hood and place a box fan on the opposite side of the car blowing towards the shop. A 5.6 liter V8 produces quite a bit of heat. And I can work in 50F easily, but its a problem at 95+.
    Since my shop is not a full time shop I installed a window AC unit ( yes, against the HOA rules, but its out of site and nobody has ever said anything in 18 years ) I have an 18,500BTU unit I bought for the 2 car garage in my previous house. I now have a 3 car garage and the unit is “Adequate”, efficient? No. I bought it in 1988. And I know the technology has changed tremendously in 22 years. Cost effectively I don’t see installing a new unit soon. I only use it 5-10 days a month MAX during the summer. So a new AC units break even point, will be quite a few decades away.
    As Marc has done, my next step is to insulate and tighten the garage doors to prevent leaks. The attic is 3/4 insulated with a finished room over the garage and I will insulate the last 1/4 this summer . The side walls were never insulated and it’s a full garage now so I don’t see that happening. Luckily the garage doors face east and the south wall has a couple of huge post oaks, taller than the garage that shade it very well. Insulating and sealing the garage doors is next on the agenda.
    Thanks for the information and everyone’s input on Air conditioning a shop for us below the Mason Dixon Line.


  38. Gary July 15, 2010

    living in Colorado I certainly don’t have to deal with the constant 100+ degree days – but it does get hot and so does my shop. I think I’ll wait until we move someday and I have a shop built from the ground up to add A/C to the shop (unless I get a window unit). The info in your post is going to be helpful when that time comes – thanks.

  39. Stacy August 7, 2010

    Good solution. One other idea is to contact a local HVAC guy and ask him to keep an eye out for someones old system. Every now and then they remove systems that are just a little aged and will let them go for a song.

    • Bill Wheaton August 8, 2010

      [Palm to forehead] Of course! What a good idea. Especially since they just got done putting in about 6 grand for our house AC.

  40. Jim Record October 9, 2010

    I installed a mini-split in for my 20x24x10 workshop in 2009. It has provided both AC and heating here in Colorado. I built the workshop with 2×6 walls and insulated with blown-in cellulose insulation. The result is an inexpensive to run system that keeps my workshop comfortable the year round.

  41. Ira December 13, 2010

    The mini splits are great. I’m going to build a stand alone shop soon and use hydro radiant heat in the floor and a mini split for the AC.

    Also, it sounds like everyone is cognizant of and taking advantage of using their fellow taxpayers’ money to finance their HVACs. While it’s convenient to think of these credits as “free,” please remember that this type of social engineering is part of what’s gotten our country into this mess: homeowner tax credits, cash for clunkers (good grief!), and sundry other subsidies. Please keep in mind.

    Your site is excellent, Marc. Isn’t technology marvelous!

  42. Terri January 9, 2011

    I also live in the Valley of the Sun, and have had the same issues with contractors more than once, whereas I NEVER had experiences like these back east! I found this thread because I, too, am considering AC in my garage (hobby small metals as well as vintage materials). AND I have the SAME issues as far as the HOA.
    Now, for my needs, I don’t mind it being noisy IN the garage, but it can NOT make much noise on the outside (it’d be closer to the neighbor’s house than my house AC compressor). BUT, even more, it can NOT be visible. I have no windows in my garage, just a door to the patio, but it’s right next to the gate to the street (as well as the door to the kitchen, of course). I’m hoping I can get away with a simple portable wheeled AC – doesn’t need to be COLD in there, but it’s gotta be less than the outside air temp. So I have to see how/if it can be vented thru the small wall area on that side that is not visible from the street, or that side door (I’m not sure that is allowed by Fire Code, though).

  43. The alternative energy (or in this case energy-less) route is to bury tubes (like culvert tubes or what ever works in your area) in the ground that passes through the wall or floor and allows cool ground temp air in to cool the shop. So what perfect solution could a woodworker use to pump air out and thus pull cool air in? A cyclone dust collector (DC) that vents outside. That DC would be perfect to pull the cool air in and pump the hot air and dust out. Once you have installed the system, you would have no cooling bills and a cool (like bragging rights COOL) shop. You could also have solar fans if needed that pump air out. You could plant a hardwood tree to shade the intake…

    • Bill Wheaton May 3, 2011

      Wow, this is a really good idea. I might do it.

  44. You know, at it’s simplest it is all about heat exchange. You are basically building a heat exchanger. You are exchanging heat out of the incoming air and into the ground before sending that air into the shop. In many locations the temperature underground is about 55 degrees. Compare that to Mark’s 120 degrees and you can see the value. People building a new shop can put the tubes under the shop or near the shop. The actual heat exchanger can be really low tech or high tech but the principles are the same. Where I live we do not need to cool our shop but we do need to heat it. I will be building a solar heat exchanger for heating the air. So far that heat exchanger is looking like a green house rather than a solar panel.

  45. I am leaning towards an old swamp cooler I am in Fresno it gets in the 100 to 110 most of the normal summers if i can keep the shop to a bearable 85 I am good but the down side may be the movement of the wood in the shop all that added moisture may not be the best thing, did you think of a swamp cooler first it is way cheaper to run


      I did use a swamp cooler for a while but didn’t really enjoy the extra humidity. It didn’t affect my wood or tools very much but it just wasn’t very comfortable for me. Plus, toward the end of summer, the swamp cooler doesn’t work anymore due to the increased humidity.

  46. william June 18, 2012

    Just purchased a Mistubishi 24,000 BTU outdoor (commercial unit), made in Japan (most of their consumer stuff made in Thailand) on eBay for deployment in an residence in Austin TX. Still deciding between various indoor options (cassette, wall mounted, ceiling cassette or horizontal ducted). Paid about 1000 for the outdoor, and but indoor I must buy retail cheapest is wall mounted indoor $1300 or most expensive ducted cassette type PEAD, for about $2500). The PEAD line is very interesting. It basically gives all the advantages of a ductless system (no return air required, outdoor compressor, indoor handler, etc) AND enables the deployment of a crude but effective PVC “blower feeds” around any space. Instead of the indoor unit discharging its (cooled or heated) air through its vent (wall, ceiling) it sends the conditioned air into duct connectors.

    Master plan: By utilizing 6-8000 BTU’s more than I need for the space (getting 24,000 vs 18,000 or 12,000), I hope that ONE big mini split does the same work that a $8,000+ custom ‘traditional’ system and have it all installed for $4000.

    As it happens the outdoor unit I purchased, PUY-A24NHA4 will support 2-12,000 BTU handlers from same compressor, so that is also an option I am considering especially appealing if you can on/off control one of the two blower units. This would enable the system to cool/heat a master bedroom, but then have option for it to cool/heat a guest bedroom which is not conditioned all the time. And, even though is 24,000 BTU unit, it consumes less than a comparable 12,000.

    Motorcycle engine size is nice analogy here. Sure, a 250CC machine is fine or most riding and can even move along the highway OK if a bit nervously and at the edges of the bike’s ability. Ride a VFR Interceptor which far more power than is needed and it will deliver it instantly and with remarkable efficiency due to fuel injection and engine technology.

    Particularly true with split AC systems. Get more power than you think you need by factor of 1:1.5-2

  47. Greg July 23, 2012

    I had one installed in my garage, as previously disclosed, and I am very pleased. Our unit is a different brand name but serves the same purpose. I installed a window unit in my small shop and wished I had gone with the split. Once the window unit wears out I will have this unit changed to the shop.


      Thanks Greg. We are currently trying to decide what to do in the new shop. Really leaning toward a beefed up ductless mini split. But in this area, it seems particularly difficult to convince installers that they want to do the job. Frankly, the noise of a conventional system is just too much for the filming I do. So one way or another, we’re going with a ductless mini split.

  48. Brad September 8, 2012

    We love our mini-splits. We have three Fujitsu heat pumps in the house (9k, 12K, 15K BTUs) with one more planned for the shop. Not only are they more efficient than central units at 21 to 26 seer, you only cool the rooms that need to be cooled! Our power bills are significantly lower with them installed.

    I bought the systems from a AC contractor friend. With his helpful consultation, I did all of the installation except for the final vacuum pull and charge release. Total cost to install all three systems was about $5600 and a few hours of my time. They’re super easy to install unless you need to pull the coolant lines and power vertically through a wall.

    One very important health liability that I haven’t seen mentioned here yet: Be on the lookout for mold growing in the fan area. In our house, two of our units cool constantly for many months out of they year. While cooling, they get wet from the condensation. Cooling 24×7 for weeks, there is no opportunity for them to dry out. The constant moisture is ideal for mold growth. As a result, they require a periodic disinfectant cleaning. You can get a concentrate designed for cleaning the inside mini-split units. After proper dilution with water, you simply spray it over the coils and fan with a garden sprayer. It does the deed, then the fan will dry up any leftovers which doesn’t run down the condensation drain.

    If you can run the electrical, cut a hole in the wall for the lines, run a condensation drain, and avoid kinking the copper lines, you can install it yourself in a few hours. Call the contractor out to pull a vacuum and release the charge.

    Don’t forget to clean the filters! :)

    • James D May 23, 2013

      Thinking about a mini-split for a 15×24 garage shop. I’m curious…why are the prices for the total install so high? I see prices for 12000 BTU systems at about $1K (maybe a little higher) and thats for both units (indoor and outdoor). The process isn’t very labor intensive, so why the $5K price tags?

  49. Jason F June 29, 2014

    Marc, you talked about mini splits being more efficient than other systems … now that you’ve had yours installed for a good while, can you comment on the amount your electric bill went up since installing the mini split. How much does it cost per month to run a system like the one you have?



      Honestly I am not going to be much help there. Soon after the shop was finished we had solar panels installed on the roof. My electric bill is the same every month now regardless of how much power I use. :) Furthermore, Nicole pays the electric bill and I probably wouldn’t be able to answer that question either way.

  50. Jason F July 1, 2014

    Wow, that must have cost a fortune to install enough solar panels required to power the the mini splits in your shop. Please share the link to the install on those, and any info you can about pricing and etc.

  51. Jason S July 4, 2014

    Solar panels have come down in price a lot! You can even get some basic kits on Amazon that are very cost effective.

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