My air handler/evaporator and heat pump (Carrier 4 Ton) is vintage 1979. The heat pump seems to be performing below baseline. I characterised the entire system several years ago just so I had a baseline for comparison. At 40 degrees outside ambient it used to give me about 20-25 degrees heat rise from cold air return to the heat vent closest to the air handler. (w/aux. resistive elements off). Right now I'm getting about 13-15 degrees. I cleaned evaporator/condensor, replaced filter, and oiled the air handler motor and am sure air delivery is fine. I suspect refrigerant charge has fallen a little below normal over the years. However the temp of the suction line where it enters the air handler is 150 degrees which is approx. the same as my "known good" baseline measurements.
I will probably have someone come out to check refrigerant charge but it's probably time to replace the entire system.
Here are my questions:
1. For a new system should I go R22 or Puron?
2. My lineset is about 75' long. I can relocate the condensor pad to shorten the run to about 40' but prefer not to. Is there much efficiency gain reducing the line set run?
3. Yes, I know that getting 3 bids, getting a manual Load J, and getting a good installer is more important then brand of unit. However are there component brands that should be avoided or given preferrence?
4. I know that the match between condensor and evaporator is key but is there merit in replacing the air handler? (the blower and aux. resistive elements are fine).
5. Any other tips in finding a good contractor? I don't know anyone that's had HVAC work done lately. (competance trumps cost IMHO)