Let me start by thanking the techs that support this site. I've learned alot.
I purchased a lake house in East TX and it has 4 AC units. 2 are split units and 2 are package units. The house was built in the 50's w/o AC. I don't have the money to replace all 4 at once. Which would you recommend or better stated what order. I have them listed below in the order I feel they should be replaced.
1.The main part of the house upstairs (all bedrooms) has a split unit with a gas furnace. It smells like gas out of the difusers everytime the furnace fires regardless of the fan being on "on" or on "auto". Two AC guys said heat exchanger's ok and their meters picked up no gas or CO. The ductwork was a disaster and now after some work by me, just really bad. Unit is about 25 yrs old. Area is about 1500 sq. '. Tons of windows and no insulation in walls.
2. The main part of the house downstairs living and kitchen area has a package unit w/ electric heat- no heat pump just the meter spinning kind. The unit was installed 15 +/- yrs ago so it's the newest. This part of the house around 1700 sq. '. Tons of windows and no insulation in walls.
3. Attached but self contained guest quarters with split unit with gas furnace 25 yrs. old. Pilot keeps going out every day or three, and smell of gas odor in this unit but not as destinct as upstairs main house. Part of house is seldom used and also lots of windows and un insulated walls etc. 1200 sq. '
4. Downstairs in main house includes study, laundry area and storage room. Less windows and very shaded on one side so unit seldom runs on heat or cool. 25 yr old package unit with elect. heat. 900 sq. '.
Last electric bill around 400 so I know bang for the buck is the main downstairs unit but the health risk of the upstairs gas unit has me leaning that way. No one I've talked to "recommends" doing a manual J. They "know the area and this type of construction". So I'll be doing it I guess using the HVAC-Calc. The guy I'll probably use is the only one more concerned about ductwork upstairs than the unit I chose which makes me happy. Just have to go over the manual D with him I guess. Considering the size of the project and the fact I only live here 3 days a week- what do I look for in a unit? He's a Carrier dealer and told me Comfortmaker is good stuff. What type of equipment is the best bang for the buck. For example is a VS furnace worth it considering the area is just bedrooms? 2 Stage? A scroll compressor better than piston? Stainless steel heat exchanger vs. aluminized steel? Sooo many choices. When buying a car you know what it drives like before you buy but not with a new ac system. Thanks!