Energy retrofit: HVAC strategy?
I’m planning an energy retrofit/remodel of my 2000SF single-story home in Dallas TX, involving substantial insulation upgrades and thorough air-sealing.
The existing HVAC is 20+ years old, and one or more components may be nearing the end of service. By today’s standards the components are not efficient. It’s a forced air system (natural gas furnace/AC). The 5 ton AC compressor is outside; the furnace and blower are in a conditioned mechanical closet; the ducts are not insulated and run in a vented crawlspace; return air registers merely vent to the crawlspace (no return ducting); the plenum pulls air directly from the crawlspace through a whole cut in the floor under the blower/furnace.
As part of the remodel I’d like to clear out the mechanical closet to make more room for the 2 adjoining bathrooms. There is no other conditioned space to house the mechanicals. The house roughly divides into (2) 1000sf sections: an open-plan public area, and a divided private area of 3 bedrooms and 2 baths.
The water heater will be replaced with an efficient exterior demand model. This is kind of sad, as my existing water heater, a Ruud Monel works fine and is original to the 1954 house; it’s actually quite beautiful, and deserves better than the mech-closet.
For HVAC, I’m considering a packaged unit that can be housed outside like the Trane XL16c or various arrangements of heat-pump mini-splits with multiple heads and/or limited ducting. Assuming the house will be tighter, I’m hoping to downsize the equipment, and also incorporate an HRV/ERV, if it makes sense to do so. The remodeled crawlspace will be sealed, though not necessarily insulated. There is a partial, low unconditioned attic, but much of that may be converted to cathedral ceiling.
Given the existing setup, and assuming new and efficient equipment, I’d appreciate advice/thoughts about how I might best go about improving my situation, or at least thinking about it.
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