I am trying to figure out what size Trane XL19i heat pump would generate the least annual electric bill for my house in Pittsburgh, PA. My home is approximately 1500 square feet and is fairly well insulated for an older brick home in this area. It also has newer energy efficient windows. I believe my cooling needs are approximately 30,000 BTU and my heating needs are approximately 60,000 BTU. I plan to have a system consisting of just a heat pump with additional auxiliary electric heat strips inside a Trane variable speed air handler. I’ve decided to go 100% electric for both my heating and cooling needs, which is very uncommon in this area.
Based on the cold winters and moderate summers here in Pittsburgh, how would I determine what size (in tons) of a Trane XL19i unit would use the least amount of energy over an entire year by taking full advantage of the two stage capability of the XL19i? I’ve heard that you really can’t oversize the XL19i because of the staging, but I’m not sure if this is true. If that is not true, what would the possible issues be of a two stage heat pump that is oversized? Too much air for the ductwork, loss in efficiency, possible failure of the unit, etc.?
I do plan to have a Trane dealer that I’ve been talking with come over to give me an estimate, but I would prefer to do the sizing calculations myself and to find out as much information as possible before I do as a double check, if that is possible. Also, does the XL19i come with only R-22 right now and is it the only heat pump on the market that operates at 50% capacity in its low stage? If the XL19i is available with only R22 right now, does anyone know when Trane is expected to have the XL19i unit available with R410A refrigerant?
I really appreciate any help or advice you can provide.