I’ve just learned that installing a ductless, split-level air-conditioning unit in my new garden shed/utility building will be financially out of my reach. A quote obtained early this year was about $2K, but one obtained this week is literally double that, with one option reaching almost three times as much. It looks like the supply chain crunch has cleaned out the older stock of units, and the only ones available now cost an arm and a leg. Guess what I won’t be buying?
The alternative is to install a window A/C unit for summer use. (In winter I’ll plug in an oil-filled radiator, which’ll take the edge off the cold at an affordable energy cost.) Yes, a window unit’s not ideal, and if anything goes wrong you basically have to throw it away and buy a new one: but it’ll cost only about a tenth of a split-level unit, so it’s something I can afford. It’ll be a smaller unit, about 10-12,000 BTU, because the building isn’t very large. However, I’m in a quandary about mounting it. In a metal building there’s almost no wall thickness to speak of, so the “conventional” window frame or wall mount simply won’t work. The thin metal will probably buckle under the strain. Clearly, I’m going to have to mount some sort of reinforcing bracket (see, for example, this one), but that, too, depends on a wall 4″-11″ thick. I haven’t (yet) found one that can work on a metal wall less than 1/4″ thick.
I guess one solution is to build a makeshift window sill out of wood, on the inside of the wall, with a panel below the window to take support bracket screws, and “legs” that reach the floor to support the weight. However, is there a better way? Can readers who’ve had to do this suggest an alternative? If so, please let us know in Comments. I’m sure I’m not the only person who could use such advice. If you can include a suggestion on where to find anything specific you mention, that would be very helpful.
Thanks in advance.
Peter
It sounds like a portable AC unit might meet your needs better. Those simply need a place to vent outside via a hose, like a dryer vent. My parents use one in their garage which they've converted to an office/spare bedroom, and it works quite well. Something like this might be the right size for you.
https://www.homedepot.com/p/Toshiba-8-000-BTU-6-000-BTU-DOE-115-Volt-Portable-Air-Conditioner-with-Dehumidifier-Mode-and-Remote-for-rooms-up-to-250-sf-RAC-PD0812CRRU/311290367
They will also give better security because they don't require a hole big enough for people to crawl through.
I'm planning to get one for my shipping container shop.
I've mounted multiple window units in holes cut in shipping containers. In those cases, I framed in the opening with treated wood, screwed together in an "L" shape top and bottom to cover the corrugations, and flat pieces on the sides. I screwed the flat pieces of the top and bottom "L" and sides directly to the steel with screws installed from outside.
I suspect your building has less substantial sheet metal than a container. In that case, it is likely that the framed opening will need support from bottom to top on both sides of the opening, to prevent the weight from pulling the wall outwards.
In other words, frame a window including the support, and then put an AC in it instead of glass.
You beat me to it Marion. I use one in my bedroom in NH for the few weeks (lately a couple of months) where it's too warm to sleep well.
Or you could use grown up tinker toys
Boltmaster 1-1/4 in. W X 36 in. L Steel Perforated Angle
Sold at Ace Hardware, plenty of others. An angle steel support for your window AC. I never recommend soft pine 2 X 4 versions given the AC drippage and rot etc.
Let me also drop this link:
https://www.amazon.com/gp/product/B00UV3LH8U/ref=ox_sc_act_image_1?smid=A3IN1VG2XLZWVW&th=1
I have a Senville unit just like this in my container workshop. I installed it myself, and am very happy with it at 2+ years and counting. The price is still pretty reasonable, in my opinion.
If your AC contractor wants $1k+ to install something like this, you don't need a window unit, you need a different AC contractor.
Second on the portable. If needed, it can be used elsewhere in the house. The vent is easily mounted in any standard window. Here is one that does cooling, heating and dehumidifying.https://www.homedepot.com/p/Whynter-14-000-BTU-Portable-Air-Conditioner-with-Dehumidifier-Heat-and-Remote-ARC-14SH/202555706?source=shoppingads&locale=en-US&pla&mtc=Shopping-CM-F_D29A-G-D29A-029_017_ACS_FANS-Multi-NA-NA-PLA_LIA-2995903-NA-MinorAppl&cm_mmc=Shopping-CM-F_D29A-G-D29A-029_017_ACS_FANS-Multi-NA-NA-PLA_LIA-2995903-NA-MinorAppl-71700000032403379-58700003840533702-92700030729182093&gclid=EAIaIQobChMI_Y3ltvGn9wIVL8mUCR0REAvKEAQYASABEgJ7j_D_BwE&gclsrc=aw.ds
Portable units generally run a lot more than window units. Portability has a price.
For the window unit, build a floor-to-ceiling frame of 2x4s: two vertical legs, two cross braces. Flat works just fine, and you get a wood 1½" thick "wall" to mount it on.
If you want enough cross-braced rigidity, a sheet of plywood, of any thickness, over or under will suffice.
I did the same thing with plywood to put a window unit into a much larger window, and just sandwiched the sheets, with a 2×4 middle frame.
Made the hole the exact right size, which helped out with sealing the thing.
FWIW, for the one-time trouble of mounting it at or near ceiling height, the area it cools best will be everything in the shed lower than that. Just make sure the power cord will reach the outlet, and get one that has a remote control, so you can turn it on and off from anywhere.
And given you're talking about a sauna box (writer's roost or somesuch, I presume?), you might want to hide it from the sun somewhat with shade cloth or tarps, over top, and on the sunny sides, to cut the workload on the a/c, and the pounding on your wallet from running it. Poles, shade cloth, and tarps are cheaper than kilowatts.
If you wanna try bombproof, a tin patio roof over the shed can last for years, be covered with white roofing compound, and shortstop a lot of that hot Texas sun.
For whole hog eco-nut-level of trouble, a couple of solar panels, a couple of deep discharge batteries, and a charge controller would let you rig the inside with permanent 12V RV lighting and an auto sound system.
You can put in the bowling alley and shooting range next year. 😉
Let me also put in my $.02 on portable units.
They can work fine as a supplemental unit in a house or larger structure. However, they rely on exhausting the heat outside via a ducted vent. If used in a small enclosed area, this exhaust will quickly result in negative air pressure inside the cool space which will have a very detrimental effect on the cooling performance. The only option is to provide some kind of outside air intake, which will itself cancel out a large portion of the unit's cooling power, depending on outside temperature.
I don't recommend them for well built and insulated sheds and other small outbuildings. I tried them in my containers and within one summer had mini splits instead. The portables were wasted money.
Three options
1) Add structure to thicken the wall. Structural members extend to floor and perhaps ceiling.
2) Mount it on the roof and fabricate the necessary ducting.
3) Build a ground supported structure to support the A/C unit.
I have not used them, but AC-Safe makes brackets for supporting window air conditioners. The heavy duty screw-in type runs about $50, and the "slip-on" no tools version is about $40.
Additional problem with the portables is unless you have a hole drilled for the drainage, the moisture pulled out of the air will drain into a bucket, which needs to be dumped. I used a portable in my shed office for a couple years, but I couldn't run it overnight or on weekends when I wasn't working because I couldn't be here to drain the bucket before it overflowed.
I think you need to frame out a window and section of wall and mount your window unit to that.
For heat, I use an electric oil radiator. It is silent and keeps my office comfortable in what winter we have in Florida (even nights that dipped into the 20's). It tucks away neatly for the summer.
Second Aesop's comments about adding a shade white metal roof over that shed (and I'd add serious overhang to keep evening sun off the walls) is a bit more up front but given power costs climbing will pay for itself.
I'm not fond of semi-annual replacement of shade cloths and other "cheap" cures. The older I get the less I like redoing things.
However, that said a western wall plastic lattice with some potted grape like plantings creates a nice evaporative cooling shade.
Or as he said cheaper than kilowatts.
It’s possible to buy a good used AC wall unit. People that put in a central air unit often sell their old ones. Craigslist and OfferUp are good sources. $600 new vs under $250 used.
For 120 vac go with a 15,000 btu wall unit. The largest corded 130 vac AC. It’s only a Minor difference in cost. And ac wall units are just for one room. Always oversize with an AC.
Metal bracket is your best bet for mounting.
Something like this:
POPMOON Wall Mounting AC Brackets up to 440lb/200kg Split Air Conditioner Bracket 21 5/8" Lx16 H Bracket Air Conditioner Bracket Set Adjustble 9000 Btu to 36000 Btu https://www.amazon.com/dp/B07Z9JHDT5/
Amazon also has minisplits. Installation is not that much, and it’s a lot quieter. Wall units are noisy. Plus you can also use it for heating. You can use concrete blocks to mount them on, pour concrete, or buy a plastic pad.
Dragonlady most of the portable units I've seen including mine blow the heat and moisture out the vent tube. My 8K unit has done a wonderful job keeping my 12 X 15 bedroom cool and dry in our summer humidity.
We even use a floor fan to blow that cooling air (actually circulating air) from the bedroom to our living room when we are watching TV. Works pretty well moderating the heat and noticeably dries the air.
My dehumidifier unit has a drain bucket.
I think I'll get a second unit as mine getting older.
There are a couple of options if you still want to go the minisplit route. ClimateRight and MrCool are plug and play options that do not require HVAC guys to put in. I have installed 3 of the ClimateRight units on my property (one associated with a metal building) and a good friend of mine has done the MRCool. Thus far my experience has been good. Oldest unit running 4 years now. Price should be about half of the number you referenced above. Just thought info might help. ~~dirtroadlivin
I wonder if the very minimal insulating value of thin metal walls can justify spending any $$ on an AC unit plus the (rising) cost of power; plus maintenance costs and effort etc.. Reducing direct solar heating as per Aesop's suggestions makes more sense to me, plus perhaps a low RPM ceiling fan? But I live in northern Alberta, so those ideas may not work in Texas with high humidity etc.?
For a metal toolshed the route I took was to cut a hole for the window unit high up, and built a supporting frame from redwood on the outside to hold up the A/C. Chose redwood for resistance to rot.
This was in Phoenix, so also had two inches of hard foam insulation on all sides and roof, that was a must.
For those wondering about insulation, don't worry. I'm putting in closed-cell spray foam insulation before using the building for anything!
Snake is correct. That is a good unit. Your AC folks must think yer desperate or stupid if they want to charge you $X that.
Plus the minisplit will give you heat in the winter at less cost than the resistance/oil filled radiator.
They aren't hard to put in, really…and they are VERY efficient. If you can drill a hole and run the lineset through the wall, your halfway done. Last time I saw you you were mobile enough to do that.
In Japan people build little supporting frameworks and stick it on top of those.
White roofing and green climbing plants on a net on the South side are good too.
First, if you go the framing route, take a look at unistrut. It's in the electrical department. I had a project and 12' of unistrut, around $30, was cheaper than perforated square tube. They use it to build support structures for conduit and I've seen it used for other support structures.
But you you might look at a dehumidifier for a small space, or an AC with a dehumidfying mode. Drier air will be more cooling than just cold air.
An alternative is to mount the "window" AC inside and duct the condenser part to the outside (might need a fan to get good air movement). Or if you are just cooling you while inside, you could point the front toward your work area, with ducts, and let the heat from the back vent out any roof vents you have.
Mini Splits are going up in cost, but many HVAC contractors charge a lot for them since they are, themselves often toss when they fail units. They are critically charged so no real adjustments. And the ones that are what you want are basic refrigeration circuits with a lot of electronics controlling the compressor, fans, and electronic expansion valve in real time. (Cheaper mini splits are just standard refrigeration circuits and don't have the performance or cost savings)
As for heating, if the shed isn't well insulated and kept heated all the time, you'll so better with a radiant source of heat in winter. For short jobs you use a brooding heat lamp to keep your hands warm. For more time and if the shed is leaky as my garage is, you might use a propane patio heater. The get real warm for a convection or "heat the air" type heater in a shop, you have a long wait for that to heat up all the cold surfaces. Radiant heats surfaces directly.
If you want long term, consider a package unit. Traditional heat pump or AC, but sits outside and had ducts for supply and return. Not cheap, but just need power and duct work, maybe a sheetmetal rain hood over the ducting from the unit to the wall.
Those mini-split systems are the big thing for motorhomes now. Gets rid of that big, noisy, heavy unit on the roof. Only drawback for them is they cost 2X the price of the legacy roof AC units. However, I hear that you may be able to get by with only using one, instead of the typical two roof units.
I used a portable AC unit in a 37ft motorhome I was working on in TX a couple years ago. Bought it in Home DEpot. Outside was about 97F, high humidity, in east TX. Inside, it would bring it down to 80F. Vehicle had good insulation, along with double pane windows. HD had two ratings of btu systems, I was using the smaller version, IIRC. ISTR it was an LG brand.
None of the (3) builtin AC systems were working, so the portable was an easy route to make it possible to work inside. Ran it on the oem 7.5kw diesel generator. Not much of a load for it.
Take a look at a PTAC. Units that are used in motels rooms. Get the wall sleeve, grille and unit for about $1000-1200.00 I would recommend a heat pump type with electric backup heat. Uses 240 volt for lower power consumption than a 120 volt window shaker.
Jesse
If you were closer, we have 3 window units that probably still work as they were on the lee side of the tornado that took the house out.
You could have them for the cost of picking them up.
But sadly I don't think you are.
You have plenty of comments here so I hope some of them will help you.
Be safe and God bless.
What Ray said: Oversize the unit.
I use a 6000btu unit on a sleeping closet (queen-sized bed in area), and on 100 degree summer days, it's cooooooold where I'm sleeping, in about 5 minutes.
Put in the biggest unit you can get away with, because the decreased workload on the unit will increase its useful life. And make you a lot more comfortable.
And anyone who can figure out putting in an a/c window in a windowless wall, can work out a way to drain excess liquid humidity the same way, one a far smaller scale, using some plastic tubing, and a copper flange outlet. Ideally, evacuating it to something outside the building that likes water in order to grow, like a grapevine trellis shade wall, etc. 😉
This is true except in the case of high efficiency mini split units. They use a variable speed compressor to create variable refrigerant pressure to match the required cooling load. They gain significant efficiency from not constantly cycling on and off but rather running at a low speed. If these are not somewhat matched to the cooling load, the required pressure could be below the system minimum a significant amount of the time, negating a large portion of the system efficiency advantage and putting unnecessary wear and tear on the compressor.
I second Aesop's comment. Plus I lived with portables for a while. They are inefficient and extremely noisy compared to wall units, and you have to manage the water drain. One big thing AC does is lower humidity, and portables require you to handle that whereas wall units drip outside. In high humidity environments, having an AC lower the humidity is a big part of how they improve comfort.
Just frame it up as he describes, add a solar cover (you will have seen those in Africa on all the Land Rovers) and you will be good to go.
Cheapest way – dig a hole outside the window. Put in a 2"x4", cut to height of the A/C unit. Heck, if need be just make an 'X' at the bottom for support if you don't have animals/children that will bump it. We did the latter when my wife and I lived in a 600 sq/ft little mobile home at the start of our marriage.
If you want a more solid solution, dig the hole, mix a bag of concrete, and level it. Buy a bracket for 2"x4" board, attach, cut to length.
When I did it, the weight of the unit just held the board in place. If worried, you could get an 'L' bracket with some short self tapping screws to secure the wood to the unit. Just make sure not to pierce anything critical.
Both of these will avoid any structural issues with the wall. The cheap one is less than 10 dollars depending on local lumber prices, and 20 minutes of work. The more expensive one is 15-30 depending on local concrete and lumber prices, and what bracket you buy.
Looks like about $800.00 for a roof mounted RV AC unit. don't know if that would be useful for your situation. Seems like it would work since a metal shed and an RV are both basically metal boxes. It would be more secure than a window mount AC. If you go the portable route you might want to place the unit as high as possible off the ground and make the water and exhaust ports no larger than needed so gravity can take care of the water removal, which you could route to any shade plants you put out to reduce the sun blasting your shed. Good luck.
For drainage to meet code in So Ca for a minisplit drainage, one way is take a 5 gallon bucket, cut the bottom off, and fill it full of gravel. Total cost around $6 plus labor to dig the hole. I assume something similar in your area.
"I tried that, but after I cut the bottom out of a bucket, and tried to fill it with gravel, it took forever. I musta shovelled about 10 tons of gravel into that bucket, but it wouldn't stay there no ways. But it worked out, because with all that gravel piled up there besides the shed, the whole side of it was as cold as the bottom of the well in January.." – Forrest Gump