We recently had a 3 Ton Trane XL16i with VS air handler and 90% Efficiency gas furnace as back up installed.
Our house is 2200 square feet, 13 registers and basically a log cabin with insulation only in the ceiling and floor and lots of windows.
As the weather in the Northwest has cooled we have noticed several problems.
1) Vent temps of 75-80 degrees, sometimes higher, but not much.
2) The system constantly runs trying to maintain 65 degrees
3) If we ask for a 1 degree temp rise the system can do this incrementally to a point (approx 69 degrees) but if we ask for a 2 degree or more rise the temp in the house will FALL
This is with outdoor temps of around 40 degrees.
The first time the tech came out he thought an expansion valve at the compressor unit was bad and replaced it. Reasoning, the smaller line exiting the indoor coil was cold and the larger lineset was never really hot.
With this change the lineset is blazing hot, the small line still cold and the vent temps went up maybe a degree. He fiddled with the amount of charge and left again.
Came back and noted the coil (high efficiency) was very hot near the inlets but rapidly cooled. He thought something was wrong (plugged, etc) and replaced all the dryers, flushed the system and recharged. No change.
The ducts have been checked. Not intake leaks and no vent leaks.
I'm frustrated, they're frustrated and I'm looking for a fresh set of eyes to look into this. Not what I expect for the money spent.
Is this an issue with the system, the techs/installer or is the system undersized? All of the above?