Considering your climate, have you looked around to see if you could buy a used heat pump system that would give you both A/C and heat? It probably wouldn't work well if you have the shop doors open very often in the winter, since the recovery time would be slow. However, many of the newer heat pump systems can run down to temps in the 20's before they need the heat strips.
Bruce
knowing the electric rate is the key
I'm planning to be here a while so I'm looking at the Mr. Cool DC Inverter DIY heat pumps. 20 SEER, 10.5 HSPF, DIY install, inverter design, 100% efficiency at 115° and at -5°. Take a look at them, you should be able to get away with the 2- 3 ton unit. From web reviews and youtube feedback, everyone who has installed one seems satisfied.
https://mrcool.com/blog/introducing-mrcool-universal/
I'm building a 34'x46' SIP wall building 14' walls, (4) awning windows (2'x3') a 36" fiberglass man door and (2) 12'x12' insulated doors (undetermined R value at this time. Walls are 6.5" thick which yields around R23 and the trusses have a bonus room upstairs so the floor (which is also the workshop ceiling using a 12" bottom chord) will be getting spray foamed to R38.
I'm planning to be here a while so I'm looking at the Mr. Cool DC Inverter DIY heat pumps. 20 SEER, 10.5 HSPF, DIY install, inverter design, 100% efficiency at 115° and at -5°. Take a look at them, you should be able to get away with the 2- 3 ton unit. From web reviews and youtube feedback, everyone who has installed one seems satisfied.
https://mrcool.com/blog/introducing-mrcool-universal/
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You are correct, I mistyped efficiency vs. capacity. I believe I read 80% efficiency at -5° at some point. Didn't see anything about the high temp efficiency though.100% is capacity ... not efficiency. Ability to provide capacity at a given temp.
Efficiency is relative ...
Many mini-splits have a COP pushing 4 .. so depending on temps the OP would be 4x ahead with a mini vs straight resistance heat
Even with my .20 vs his .11 cost per KW .. heat pumps out perform propane cost
You are correct, I mistyped efficiency vs. capacity. I believe I read 80% efficiency at -5° at some point. Didn't see anything about the high temp efficiency though.
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So, since I live in Texas, and our winters are usually fairly mild and our summers are not, would the mini-split or the universal system work better for my application? This, of course applies to heat and AC. I won’t be using this daily. Maybe a couple of times a week, if I’m lucky. I don’t need to keep the shop at any particular temperature constantly. The system will only run when I need to use the shop. I know very little about heat and AC systems.
You do a heat load and cooling load on the building based on the building and the climate --- temps you wish to maintain.
This will give you the BTU's -- in warm climates they get sized for AC and this is normally enough for heat.
In colder climates problems can occur -- as outdoor temps drop the size of the unit obviously needs to get bigger ... in colder climates this can make the unit oversized for cooling (not good for humidity removal).
If you think about a 30 delta -- trying to make 70 in a house is 100 outside and 40 outside. What happens when it's 10 outside ? Need more capacity !
This is where the variable speed equipment can extend the range and still have capacity -- size match
We have Farmers Electric Coop. No choice since we live outside the city limits. It’s pretty high at .11 cents/kWh. We lost the ability to choose electric companies once we moved out here.