My parents have a heat pump for their 24' x 24' sunroom. The air handler is from 1991 (Trane) located in the attic and the Heat Pump outside unit was replaced in 2000 with a Trane XE1000 unit (prior unit was an XE900 I think) (not sure if the indoor coils were replaced).
I believe the outside unit was replaced due to running with a dirty AH filter for too long.
Outside unit is 1.5 tons I believe. This winter, the backup resistance coils stopped working, so the heat pump would do its job except on very cold nights when it would fall behind some.
Since the system still works and will most likely cool fine this summer, would it be wise to have the backup heat repaired now (or in the fall) or just put the money towards a replacement system that would be more efficient?
If replacing the system, would a mini-split be better for a 24 x 24 open room with 8' ceilings (and 4 skylights) and decent insulation/windows?
Current system in attic has 1 return in the wall (20x20 1" filter) and 4 supply registers in the ceiling (plus a register in the attached garage I recently discovered that must be removed and sealed ..... to prevent CO poisoning)