I got multiple offers on replacing the current 11 year old 3.5T Lennox system in central Texas. Main reason for replacement is inadequate cooling upstairs (5 degrees difference) and noisy compressor right next to bedroom. Overall, house feels warm and humid most of the time, especially upstairs. Home office I use all day is in one of the room upstairs, so lots of heat is generated by the computers.
The house is 2000sqf (1400sqf down and 600sqf up), two levels, vaulted ceilings in living. It is facing E-W, so it gets lots of sun all day long. There are two returns, in the hallways up and down.
Here are the options presented by three different contractors:
1. 5T Trane XL15i 13.5 SEER, rebuilding ducts upstairs and putting a return in each room. With an option to zone upstairs and downstairs for 4K more, or to have 3 zones: downstairs, upstairs and office for 6K more.
2. 5T Carrier Infinity 15.5 SEER, rebuild ductwork for upstairs, add returns in each room upstairs. Another options is to have 2 units, also Infinity 2T up and 3T down. But this is adding 7K to the price.
3. 4T 16 SEER Lennox dual speed, rebuilding ducts, add return in each room upstairs, sealing vents, blow in insulation in attic to get to R38, solar screens on all windows facing west (not a big fan of looking out through those), weatherstripping doors. they claim to test the whole house for leaks.
All options include MERV 12-16 air filter at the air-handler, instead of on the return grills.
Our main problem is really getting even or almost even temperature throughout the house, and being able to cool down the office without freezing the rest of the house.
To me, zoning makes sense, but I've heard that electric dampers are not really reliable. Also one problem I see is having to push 4-5T of air to cool just the upstairs in situation when downstairs is not calling for cooling.
Option 3. makes sense also becauase it addresses other factors than just throwing big equipment at the problem.
Not sure which way to go here:
- zoning with one system
- two systems
- one system w/out zoning, but addressing other factors and preventing heat from entering the house.
I would appreciate any advice.