My sister has the following: a TRANE XL 80, model #TUD080R936A1, an upflow, gas-fire, 2-stage fan assisted combust. There are 5 wires. The thermostat is also a TRANE - no model number that I could find but it's the old kind (not digital, notprogramable, etc). She wants to install a 7 day programmable thermostat--can it be done and what model
is a good one. Thanks
2 stage furnace should be mated to a 2 stage stat.
Honeywell, White ROdgers, etc are good.
Avoid Lux, Hunter, and RiteTemp.
I've been using the Honeywell vision they sell at Home Depot with zero problems. It is configurable for 2 stage heat and/or 2 stage cool. 7 day programmable with filter timer. Adjustable cph. Cost is like $120 or so. The older generation Honeywell (CT series) is decent but not as intuitive to use. The vision series is very easy to use.