I'm struggling to decide how to hvac my shop. The location is south central Virginia. The shop is 40'x50' open bay with a scissor trussed roof. Walls are 10' and the peak is 16'. 12'x12' doors are centered at either end. There is a full bathroom, 7'x11', with a 4'x4' opening above the entry door for ventilation, in one corner adjacent to the 12'x12' door. R19 and R36 fill the walls and ceiling. The doors are only R3 (cheap **** installed before I realized what had happened). I've installed a 30amp 240v circuit at either side of the 12'x12' door to feed the mini split systems. I was thinking I'd use two Daikin 2 zone 24k (12k/12k) systems. The cartridges would be mounted so two pushed air straight from either side of the 12x12 door, one also blowing some air into the bathroom through that 4x4 opening. The other two would be mounted 24' further down on the 10' walls opposing sides blowing across the shop to eliminate hot/cold spots. Without a floor layout it's probably hard to imagine it? Anyhow, any input for those that have been here?
Sizing dual mini splits for 40x50 shop
- Thread starter ezzzzzzz
- Start date
What is the N/S layout of the **** doors. If it is W or NW, I think you will need 5-6 tons. Things get pricey when you get into the multi's. Perhaps you might look at a couple single 3 ton wall units. Set them on opposite sides on the 50' walls kitty corner to each other about 15' from a corner. That way you end up with a good circular flow. You might need a ceiling couple fans to get the air down to the floor in winter as the heat will tend to sit up in the 16'. You shouldn't need them for cooling.
Using the load calculator at ecomfort I get 13k heat load and 37k cool load with uninsulated doors. Since mini splits can easily exceed their rated capability I feel two 18k 2 zone units might be a better choice than 24k units. It would allow the 18k units to run at a lower capacity than the 24k units under most conditions but still meet higher loads in more extreme temperature swings. While 2 single zone units might provide comparable performance I feel that the temp variance across areas of the shop would be too noticeable plus the airflow into the bathroom would be hindered. Attached drawing shows the shop layout. The orange boxes represent the proposed mini split cartridge locations.
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theoldwizard1
Well-known member
Two will give better hot or cold distrinution.
Similar to natural convection in a solar wall but fan powered. I'll get the systems installed and see how things work out. Adding this later would be easy too.
dcg9381
Well-known member
You have too many cars. I grew up working on the L24/L28. Dad still has a '70.
I'm in Texas. I have a 40x60x16. Foam insulation, probably R12 walls, R15 ceiling.
3 x 14x14' doors.
It's going to approach 100 degrees today. We use 2 x Daikin 24K systems can cool us well into the 70s during the day. Our roof is reflective, but our climate is a lot more extreme than your and our insulation isn't quite as good.
Most of the time we get by just running a single 24k unit, but when temps go over 90, we need both.
I'm in Texas. I have a 40x60x16. Foam insulation, probably R12 walls, R15 ceiling.
3 x 14x14' doors.
It's going to approach 100 degrees today. We use 2 x Daikin 24K systems can cool us well into the 70s during the day. Our roof is reflective, but our climate is a lot more extreme than your and our insulation isn't quite as good.
Most of the time we get by just running a single 24k unit, but when temps go over 90, we need both.
Well, too many is only relative to space and time. I've had as many as 30 at one point. Several series Z's and a myrid of land rovers. It reached a point of ridiculousness so I sold off, stripped for parts and scrapped most of it. I'm on the fence about parting with the '71 240Z. Lots of good mods like 4 wheel disc, CV axles, Quiafe R200 3.9 diff and more. There's a WC 5sp and 2.8 SC'd stroker waiting in the wings too. Anyhow, hearing you're successfully running the same mini split setup I'm looking at puts my mind at ease.