Two-Speed Outdoor Unit & HV Air Handler
I am a Commercial/Industrial Tech with 23 years experience in that field. I am considering putting in a Unico 4860 (410a TXV) air handler in my 1881 one-room-schoolhouse-turned-residence, but I am concerned about the choice of an outdoor unit (leaning towards a Lennox XP-Series heat pump), considering the 30+ degree delta T and supposed SEER-killing effects of the aforementioned HV system read elsewhere on this site. The supply ducting (SpacePak) and the return ducting are in place. Considering 20"-thick stone walls (and awesome insulation on the areas without stone walls), I'm sized for a 5-ton load. I was wondering if two-speed compressors can be used with HV systems. Seems appropriate that, at 80% capacity, I can cool and dehumidify with 48K btu in lower-load conditions (even with the fan at a constant speed) but I have no experience in the area. Any intelligent input would be appreciated!
Unico and Spacepak dehumidify fine with single stage condensers.
Might not dehumidify as well with a 2 stage. Since with only a single speed, your shr will increase a lot. Unless you get a HV with a VS blower.
Unico and soon SpacePak offer chillers, which may work better with their units.
Another brand, whose blower motors seem a cut above both SpacePak and Unico, is Hi-Velocity: http://www.hi-velocity.com/. However, some of that advantage, which comes from their optional controller for zoned systems that maintains a constant pressure down to 150cfm. It wouldn't work with a DX AC or HP though.
At 5-tons you are just above the biggest Daikin Altherma reverse cycle VRV chillers which is 4.5-tons.
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