Through the Wall AC Hole Sizes

[sick467]

My builder starts constucting my new shop next week and I will be asking him to put in the appropriate size hole for a "through the wall" AC unit. I feel like I should buy the unit before hand so that he dimensions the hole appropriately, but...

I am afraid that years down the road when the AC unit needs replaced that the hole size may be obsolete requiring building modifications. Do these units conform to standard hole sizes? If so, what what is the most common size to look for?

I will be cooling a 30x30 area with 12 foot walls (where aprox 24,000 BTU should do) and I prefer not to have a window just for the AC unit.

 

[lzenglish]

What you should be concerned with is the "Minimum" square inches of design exhaust area, for your 2 ton unit you are installing. There is no reason that you cannot look ahead, and size the hole, "or opening" for future expansion in larger tonnage! Just remember, you need to have a good gasket seal of some sort, to keep the O.A. out, and not be short cycled back into the living space in the meantime! IMO !

Wayne

 

[Mickey O]

All the manufacturers have different sizes and they change from year to year, the same model a few years down the road might be a different size, sometimes you can find a unit that will slip right in a 20 year old sleeve. Depending on where the AC is located and what you are using for building material you can use trim that's a little over sized that can be adapted if you get a unit down the road that is smaller or larger. If you're using a header/lintel add some 2 x material on the sides and bottom to frame smaller to the unit you're getting then you'll always have some room to play and will only have to change out the trim.

 

[darkk]

I would think about spending a bit more and do a ductless unit...

 

[Falcon67]

That's why they sell trim boards and shims. Buy a good unit with a decent warranty and let the builder measure and cut. This one isn't even supposed to be in a wall. I figure when it's time to replace it, since I made the hole I can modify the hole. I used screws to set any framing pieces and 16 gage trim nails, so it all comes apart pretty easy. On the outside, I put the trim up tight to the case and ran a bead of caulk around the case and where the trim meets the siding to keep the water out.

Note - most of the 15K up units will be too wide for even 24" OC studs, so he'll have to frame out a hole with a bit of header anyway. This 10K is only 1/2" short of hitting the next stud. You won't have to cut a stud to mount a replacement at least. Replacements will be close to the old one, but likely not exact. The larger units are easier to do because the case is mounted first and the guts slide in. I had to hump that 10K up complete.

 

[sick467]

Good info folks! You've given me some things to think about. Like most projects, I have a budget that is already pushed it's boundaries. I would really like to go with a "through the wall" unit so that I can have some AC for the remainder of the year, but holding off for a more expensive and installation friendly unit is temping. I have only located one unit that would be big enough to handle my space, but it appears to only come as a "window unit". And, I understand that making the hole bigger than needed is a convienient way to go, but I'm not sure how to seal it up on the outside (I wll have a traditional metal building). I'll talk it over with my builder, but in the mean time...keep the ideas coming.

Thanks,

 

[hillbill9889]

I searched Amazon for the largest throughthe wall AC I could find. Before putting sheetrock up, I cut on of my studs and built a bottom and top stud and just framed out an area big enough to accept the largest AC I could find. Insulated, put sheetrock in and walked away. Summer time came and I got my AC, I just use a Dremel to cut out the sheetrock, saws all through the outer sheathing of the garage and slapped it in.