2nd story addition heating
We’re working on an addition to a 740sf 1940s home in Portland, OR – addition includes +300sf on main level and new 2nd floor (1300sf). The existing furnace is brand new high efficiency gas, but not enough capacity for the addition. The owners do not want to replace it since it is so new. We are in the process of value engineering to bring costs down, but need to evaluate how to heat the new 2nd floor. Cost is an issue, but could possibly persuade them on a good investment.
Insulation: R-49 flat ceilings/R-30 vaulted attic storage space, R-23 walls. Existing main floor is primarily 2×4 construction, so R-15 walls most likely.
Any thoughts for recommended system to heat the 2nd story in this mixed old-and-subpar / new-but-not-totally-tight envelope?
I appreciate any advice you can give – thank you!
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