Hello,

I have the following systems, each set is functional and individually controlled by two separate Trane Weathertron BAYSTAT240 thermostats.

Set 1:
Trane Weathertron: BAYSTAT240
Heat side Trane XE78: TUD080C936A1 (Date: 02/1993)
Cooling side Trane XE78: TXCO36C4HPB0 (date H06)
Heat Pump Trane XE1000: TWR036C100A0 (Date: 1993)

Set 2:
Trane Weathertron: BAYSTAT240
Heat side Trane XE78: TUD100C948A1 (Date: 02/1993)
Cooling side Trane XE78: TXCO43C4HPAO (Date: ?)
Trane XE1000: TWR042C100A1 (Date 1993)

Each is currently wired according to the following configuration (see pictures below):

Blue = present but not connected = 24 volt common
Brown = T = outdoor thermistor (not used on new Honeywell)
Orange = O = reversing valve
White = W with jumper to X2 = First stage Aux. Heat (X2 = Emergency heat)
Red = R = 24 volt hot
Yellow = Y = first stage compressor
Green = G = fan
Black = present but not connected (sometimes connected to X2 in other systems)

I would like to be sure to use the full 3 stage heat/2 stage cool functionality of the furnaces/heat pumps with the 2 new Honeywell 8320U thermostats for each set. Currently the cooling may be 1 stage? Would it possible with the new thermostats and existing furnaces/heat pumps to use 2 stage cooling? I will add pictures of the heat pump wiring connections tomorrow.

What should the wiring schematic look like?

Many thanks for any help.

Best Regards,

Brent

From what I see you have 1 stage of cooling and 2 stages of heat on both units. You will need two separate thermostats one for each system. The 2 stages of heat are heat pump and then the furnace itself.

Look at the sticky notes at the beginning of this board for wire color / letter conversions. If in doupt of any connection trace it out. There should be diagrams on the blower door at the furnaces and outside on the heat pump service door. (You also have a add a relay Black item last photo on right side). I do not exactly know what its purpose is for but it has a common and yellow but no other wires?

Your question regarding two stage cooling, no you cannot make this two stage cooling because you only have one cooling unit per system, Good luck, Mike

Looks like you added a couple of pics. Sorry but still no cigar.

Thank you for the help- I am updating the original post as I acquire new information to help others with similar questions. Since this is only 1 stage cooling, any thoughts on adding a swamp cooler (port-a-cool 24") to my central ducting? Couldn't I add two one way valves to the ducting to Y into the main ducting: one post furnace and one post swamp cooler. Considering some units run humidifiers, a swamp cooler wouldn't be much more? Though I wouldn't want to blow out my ducting- need to check on the CFM output of the swamp cooler and ratings on the ducting?Someone else mentioned this looked like is has a fossil fuel kit- can you confirm? Maybe I could run some veggie oil through it if it does have an oil burner (didn't look like it to me).

I checked on the thermistor- they are not the same as resistance temperature detectors, but maybe I can just plug one in where the thermistor is and use the thermistor wire.

Houston (many thanks) on another site (HVAC Mechanic - Free answers to furnace, heating, heat pump, and air conditioning problems) posted me the following pics and programming recommendations that may be of help to others:

Aux and E = white
Rc and R = red
O/B = orange
Y = yellow
G = green
C = blue (optional) may be connected at common on furnace and thermostat for permanent backlight and no need for batteries.

option 170 = 7
option 190 = 0
option 200 = 1