Is using a single mini split to heat and cool my “dream house” going to result in acceptably even temperature distribution? The house will be well enough insulated with r60 ceiling, r40 walls, r30 basement and r24 below slab and well sealed (under 1 ACH goal) with great fiberglass triple pane windows that barely crack r5. I’ve attached the tentative floor plan to illustrate my concern. Though a mini split will be sufficient heat/cooling power the temperature difference in the distant bedroom vs the main living areas is asking for trouble, I believe. The dashed lines in this plan represent proposed ducts, with the three closest to the right rear corner associated with the ERV that pulls from the two full baths and exhausts to the hallway. The rest of the ducts are outputs from a small air handler in a closet (in the foyer). The intention is this closet has return air grills on 2 sides near the top and it’s output ducts end in floor registers around the perimeter. I’d also place return air grills above doors along the hallway to provide a flow path when the doors are closed. The smallest modular air handler, I can find, is capable of moving 1400CFM, HUGE OVERKILL though it does feature a 1/2hp ECM motor. I’d like to control the air handler based on comparing temperature in the master bath to temperature near the mini split with a 1 degree difference (either way) commanding 400 CFM and flow proportional to temperature difference so equal temperatures result in no flow.
With such a control system the mini split is always “master” and the air handler only moves air to equalize temperatures. Does anyone know of such a control system?
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