I live in a two story, 3800 square foot house in Pasadena CA that was built in 1901. The house originally had gravity heating. This was upgraded by a previous owner to forced heat. There are two zones: on the first floor, the heater is forced gas where the old gravity heat ductwork was converted to return vents and new supply vents were added. The second floor is a gas heater and air conditioning located in the attic. New supply and return vents were installed. The system in the attic is manufactured by Payne, The condenser has the following Prod# 565AJX04800AEAA.
I’d like to add AC to the first floor. The installed unit on the second floor is inadequate to cool the whole house. When it is 90+ degrees outside, the house is about 77 degrees. My wife would like the house to be between 69 and 73 degrees year round.
1) What is the age and size of the unit in the attic?
2) The heater in the basement must be at least 20 years old. Does it make more sense to replace the heater and install a matched heater and AC?
3) Does it make sense to keep two separate systems? I don’t see how I could install one system with two zones since there doesn’t appear to be an easy way to extend the ductwork from the basement to the attic. I don’t want to start opening walls!
4) What would be the proper size unit for the 1st floor? It is about 2000 square feet with 10 foot ceilings and lots of windows. I’ve been getting quotes from local contractors with sizes from 2.5 to 5 ton ACs.
I’ve been doing a lot of research and reading the postings on the site. All the contractors I’ve talked to so far seem to come up with the unit size based on experience. I have yet to see any of them pull out a calculator. I’m inclined to run to Sears and purchase a couple of window units :>).
Any suggestions and help would greatly be appreciated.