HVAC setup in small basement
I am finishing my basement and am looking for some feedback on the HVAC selection. I’ve posted about the basement in a prior post https://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/101308/basement-wall-assembly-climate-zone-3a but some of the pertinent information is: climate zone 3A, 1500 sqft space, walls and floor will be insulated with 1” rigid foam with the walls having R13-R15 fiberous insulation installed in the cavities. The basement will be moderately air-sealed (as in I’ll seal it the best I can but I’m not a pro). The current HVAC setup has a heat pump and air handler system for each of the finished floors (3 ton main fl, 1.5 ton 2nd story).
I performed a rough manual J calculation using Cool Calc software and got latent and sensible cooling load of 9,500 btu’s. So about ¾ of a ton.
Since the smallest heat pump system is 1.5 tons, I’m concerned that a traditional system would short cycle and not handle the humidity very well in the Georgia summers. I think the normal suggestions I’ve read in this situation is to put in a mini-split. Other than the ascetics concern I have with the wall mounted heads, the main issue I have is my basement essentially has 4 separate areas where the doors are expected to be closed a large portion of the time.
The only other approach I can think of is a variable speed 1.5 ton system with a separated dehumidifying unit. I’m not sure if this setup would be much cheaper than the 4-head mini-split system, plus the energy penalty for the dehumidifier isn’t idea.
So looking for any thoughts or suggestions on how to proceed. Heating loads are not a concern…the one week a year the basement gets down below 60 degrees I can use a space heater.
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