On Wednesday, December 4, 2013 7:26:45 PM UTC-5, Big Giant Head wrote:
BTW, should I even ask about replacing the HX or is that completely

ridiculous on a 26 year old unit?

I would say it's ridiculous, if one is even still available.
Have you looked at tax credits, utility rebates, etc available
that reduce the cost of a new high-eff system? Those can make
a high eff one cost the same or less than a 80% efficient one.
Calculated how much a year you will save in gas and electric?
AC involved too? How much you will save per year with a 14 SEER
instead of a 26 year old that may be running at 8?