1984 A/C replacement
I want to use the tax credits available and replace my reliable Trane air conditioners(downstairs and upstaris units) installed in 1984. They use R-12. From googling it looks like R-22 is not available in 2010 on new systems and this leaves R-410A(Puron). From reading it looks like the supply lines are going to need to be replaced for R-410A and the one running to the upstairs unit goes into the basement up interior walls all the way to the attic. And I do not want to run the line on the outside of the house to the attic. The downstairs will be ok since everything is in the basement.
Are there any other options? Like a different refrigerant, etc. I live in North Carolina so summer heat is high.
A distributor somewhere may have some R-22 equipment still in inventory, but for Trane equipment, that is unlikely.
It is quite possible that your old system was 8 SEER in which case the high and low copper lines are probably too small. If they are the right size, a few hundred dollars would get the necessary flush kit. Running a new line set is not as hard as it may seem...don't let that be the deal breaker.
I have used a line flush agent on many of my projects with great success, here is one article I found.
My Web Site
If you are going for a higher efficency unit, you will most likely find you will have to change the line size.
Also, you will probably find that unless you are going with a heat pump, or changing the heater and AC, you will not qualify for the refund.