New construction HVAC options
I’m a new member here looking for some advice on a my new home. I’m in Central Oregon which is climate zone 5B and the home will be a 1552 sq ft single level open floor plan all electric house. It is part of a small subdivision and the builder is being very flexible with options. Our 99% design conditions are a low of 4* and high of 87* with low RH. I’ve tried my best at a manual-j online and have gotten about 17,000 btu for heating and 15,000 btu for cooling. The great room has a vaulted ceiling and the rest of the home is 9ft. The home is situated with the long exterior wall of the great room facing south.
This is a budget build am hoping to make the home as efficient as possible to heat and cool with possibly treating the great room and bedrooms as two separate zones.
Factory option. The home comes standard with a wall mounted 1.5 ton Mitsubishi hyper-heat model in the great room aimed down the hallway and electric resistance heaters in the bedrooms and bathrooms. My concern with the standard design is the bedrooms becoming cold at night with doors closed and needing to rely primarily on the resistance heaters. Also, I see the lack of cooling in the bedrooms as a downside.
Option 1 +$4560 quote. My original idea was to downsize the wall mounted unit in the great room and install a horizontal ducted unit in the attic above the hallway with short duct runs to each of the three bedrooms and leaving electric resistance in the bathrooms (code requires a second heat source). As I’ve done more research I’ve learned that doing this will break the thermal envelope and drops the efficiency. Would doing this and insulating the ducts with closed cell foam be a good option?
Option 2 + ~$5,000. The HVAC professional mentioned that we could omit the ductless unit and install a traditional heat pump forced air unit for close to the cost of option 1. Upgrading to a dual stage unit would be higher cost and an option I would likely choose. My current rental has an oversized forced air heat pump and the constant on, off makes me crazy. As I’ve learned more about mini-splits I’ve been more interested in their efficiency and quiet always modulating performance.
Option 3. Anyone have any ideas?
Thank you for your help to keep my family comfortable for years to come.
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