Mini Split Layout in 30x40

[snake_plisskin]

Hello, I'm currently working on insulating/finishing the inside of my pole shed. It is 30x40 (1200 SF) with 12 foot side walls. I have R19 in the walls and plan to blow in cellulose above the ceiling (R49-R60). Eventually I want to install some mini splits for cooling and possibly heating. For now I'm going to install a propane heater.

I'd like to pre-wire the outside disconnect boxes for the mini splits to make future install easier. Attached are a few options I've been thinking about for layout with the mini splits shown in blue. I was planning on going with option 1 but started thinking that there might be a better layout. I live in South Dakota and am running 10-2 wire to the junction boxes to support at least a 24K unit at each location (planning on 2 total).

Option 1: Unit 1 centered on North wall over the workbench, Unit 2 on the East wall at the centerline of the overhead door.
Option 2: Both units placed on the East Wall
Option 3: Unit 1 centered above the window on the West wall, Unit 2 on the East wall at the centerline of the overhead door.

Any thoughts on these options?

 

[manwithtools]

With that much insulation I'd be surprised if you need two 24k units. Rule of thumb says one would do 1200 sq ft. If so, I'd go with one centered on the east wall. You could always add the second unit (12k? maybe) to the west wall if needed later on.

 

[snake_plisskin]

Thanks, Yeah I was mainly thinking the larger 24K units for heating so I could possibly get away from propane. I was thinking the Pioneer Hyperformance models that can heat down into the negatives. For cooling I definitely agree that two 24K units would be overkill.

 

[chinboys]

Multiple heads (wall based evaporator) give you better cooling or heating circulation. You can buy a two-zone unit to drive the heads.
A single head with a "large" ceiling fan will also do the trick.

Get a Manual J cooling and heating load calculation done to figure out the size of the unit for your area under its worst temperature extremes.
An oversized unit will cool down but leave you with a clammy feeling.
An undersized unit will take longer to cool down.

If you want heating, then look into a heat pump system. The new ones can pull heat from 20F. You can supplement with your propane heater or backup heating strips on the heat pump if the power rates are low where you are.

Your tall ceilings or the fact that you want to heat or cool above your head may mean a 3 - 4 ton unit on the worst days.

 

[pcmeiners]

Tell you what I have My setup is like your #2 placement of two 12k low temp Fujitsu units. I have two but have never used the second minisplit. Both units are placed further from the end walls then your placement. Hot or cool air easily crosses the distance across my garage (30 feet), spreads out, and curls down once the air hits the opposite wall . Coldest it has been here is -7 °, warmest 101°, with much capacity to spare, with just one unit, in a 1080 sqft garage (36x30). Your garage is a bit bigger, air flow is bit more challenging thus I would use two single zone minisplits, single zone units are more efficient than multi zone units, and provide redundancy if one of the units fails. My minisplit stays on 24/7, fan remains on low unless I open the garage door, then it ramps up automatically; condensation is not permitted in my garage. Make sure what ever you get, have a surge protection device on each unit. My units are 1 foot from the (10 ft) ceiling, Your insulation level exceeds mine, r13 walls, ceiling r19. Adds very little to the electric bill, approx $10-15 a month.
Check with the utility company for rebate, get the Federal tax credit, any electric wiring or an added panel also adds to the credit, I got a new 125amp panel out of it for my welder/plasma cuter mini splits.

 

[rockcrawler]

I have a 35x45x14 welded red iron shop with spray foam insulation, 2 insulated man doors and 2 10x12 insulated garage doors. I have two 24K Pioneer mini-splits (WYS024GMFI22RL-10) in the same areas like your option 2. They work pretty well and I do have to use both units to keep the temps in check when it’s hot, but I’m in Texas. I like the layout of the mini splits because one blows into my work area where my tool boxes and lift are located. If I were you, I would not go with less than two 24K units in a building that size.

 

[miketyler]

My shop is 30x40, built in 2004 with typical fiberglass batting wall insulation. Also have 10ft ceiling in the shop with two 9ft roll up doors (both insulated) and the 18k mini cools both the loft and lower floor pretty well. I point a fan in the loft at the stairs and the cool air spills down the stairway. I have Farenheat electric heat in the shop area. I'm also in Texas. I'd think 48k BTU is overkill for that space.

 

[dcg9381]

Thanks, Yeah I was mainly thinking the larger 24K units for heating so I could possibly get away from propane. I was thinking the Pioneer Hyperformance models that can heat down into the negatives. For cooling I definitely agree that two 24K units would be overkill.

I think you have it right.. And you don't have to run both units if you don't need them.
They are kinda directional. My only concern having it over the work bench is that it's going to pick up sawdust/fumes whatever you're doing on that bench.

 

[Jackfre]

For 30x40 with two units I would set them kitty corner from each other on the 40’wall. Set each about 15’ from the end wall. That creates a good circ flow of air from the two fans and should yield pretty even temps. 24’s have some pretty significant air flow. I would not have it blowing “right on the workbench.” Air off the units in cooling blows straight away from the unit but in heat it blows down and you don’t want to be directly under it. I agree that 2 24’s is a bit of overkill but having spent a winter working on a pipeline in the Dakotas (‘72) you might consider four. Should you be able to handle the load with one unit at times you can run the other in fan mode to get a good even temp.