Hello. I have been reading through here to try to gather enough information so that I can start the process of getting quotes for a new system. The background information that I have. The house is 2,340 sq ft which was built in 1981. The house in Dallas, TX. The installation in attic looks like it is pretty original. My plan is to install a radiant barrier, seal the air gaps in the attic, and add some additional insulation this fall. The current system is a 5 ton Trane AC (Model TTR060) which is approximately 13 years old. I am not sure what the SEER rating is. The heater is natural gas which is a Rheem. It looks original.

There are several reasons that I am wanting to replace the system. From what I have read here is that 5 tons is oversized for the house. The air flow is not balanced. The furnace is located on the east side of the house. The west side of the house gets hotter than the east side.

I wanted to get some information. There are lots of posts about hybrid systems. How do I calculate the cost savings? My natural gas is currently priced at $8.2282 / MCF. I think that is $84.65 / per therm, but I am not sure how to covert that to therms. My electricity is price at 11.3 cents / kWh. Does having a heat pump versus a straight A/C shorten the life of the unit? Should I make the insulation improvements before the system replacement?

I know I need to get a manual J calculation to determine the sizing of the unit. How do I go about resolving the air flow imbalance. Thanks in advance.