OK, builder mounted my tsat in living room, interior wall BUT this wall contains supply duct to upstairs. So it short cycles, definitely in heat mode and maybe cool mode as tsat's internal sensor is affected by duct.
Simplest solution for Trane TCONT803/Honeywell 8421 seems to be to install a remote indoor sensor (this is not heat pump with outdoor sensor).
Question is, Where should it be mounted???
Specifically, I had a HVAC contractor recommend placing whole tsat (or remote sensor) directly below 1st floor central RETURN. He says its a good place as it reflects indoor temp/humidity and its not a dead air spot.
Obviously, not near supply vents, windows, sun, etc. But there is moving air.. Is that a problem??
What do you pros think of the return air vent placement approx. 5ft above floor???