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A/C capacity/sizing for 1300sq ft in AZ

rattle_snake

Well-known member
Joined
Jun 25, 2015
Messages
5,230
Location
Chandler, AZ
I am running wiring for future A/C and would like to get an idea of what size of a unit would meet my needs and hence the wire size to support it. I have used several calculators (j load?) and get answers from 15k to 50k... so looking for more specific advice from GJ HVAC experts. Cooling only.

Usage:
The area is used for both parking and as a workshop. There are 2 vehicles parked in it and one or the other will get driven 2-3 days a week. Hot vehicle will be left outside until bedtime if I want to cool the building.
I think I would be OK with the minimal air distribution of a mini split (no ducting), as I could install unit over workbench as I spend more time in that area. I don't really need/expect the whole building cooled to thermostat setpoint. So this system would be used in more of a pump/cool down vs a constant hold temp scenario. Typical use might be to cool the building for the weekends and/or switch it on for a few hours while I putter on things in the evenings.
I also have evap coolers on wheels that could be used instead at certain times of the year.

PHX area, 115+ outdoor temps. Looking to get inside temps down to at least 80.

Specs;
34 x 40 = 1360 sq ft
12' ceilings, R30 to attic.
Attic space is well ventilated, foam roof deck
2x6 walls, R19
slab on grade
2 metal insulated man doors
18x10 and 10x10 insulated doors on East wall.
No windows

My WAG would be 2.5~3 ton, which would require about 25~30A electrical service.

Thoughts?
 
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toyotadriver

Well-known member
Joined
Dec 30, 2010
Messages
1,586
Looks about the right size estimate to me.

You have good insulation so I think the 2.5 would be fine. The 3 would give you the ability to cool it down a bit quicker in your hot climate. Since that's how you want to use it, given your hot climate I'd do the 3 ton.
 
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