Heating a Historic House With Heat Pumps
I have a general question about HVAC systems and backup heat. We are renovating an 1850s Colonial in zone 5b (Hudson Valley, NY) (about 4,000 sqf), and our broad goal is to eliminate as much oil/gas use as we can. Since the house needs a full renovation (including a new HVAC system), we were hoping to move over to a fully electric heat pump system. Because the roof and the roof deck need to be completely replaced, we’re planning to do a substantial retrofit there with insulation on inside and outside, and in addition, we’ll be insulating the basement from floor to rim with 2” spray foam (thanks to this group for great answers to this in a previous question).
We won’t be able to add much insulation between the walls, as both sides have historic details (and much of the first floor has brick between the plaster and exterior siding).
We’ll know more clearly about our options once we finish our insulation retrofits, and can have a proper Manual J done, but our HVAC contractor thinks we’ll need backup heat, and is guessing that we’ll need to install two 5 ton heat pump LP furnace systems. (He knows we won’t actually size it until we are finished with the insulating and air sealing). We’d like to avoid the propane backup heaters if we could.
I’m curious what the thoughts are on being able to heat our house with just heat pumps, and more generally, what people’s experiences are with larger older houses and heat pumps when it comes to comparing expense to efficiency to comfort.
Thanks in advance for your thoughts. -Curtis