Trane TCONT803 to a Emerson ST75
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Trane TCONT803 to a Emerson ST75
I have a Trane heat pump, gas package unit. It is a duel fuel system (propane and electric) and I am replacing the thermostat from the factory Trane TCONT803 to an Emerson ST75 Smart. My wiring is a bit of a question to me. The black and brown in the S1 and S2 terminals are the remote outdoor sensors (I assume). My question is this, I have a jumper wire between the W1 and X2 terminals along with a single white white going into the W1. How do I adapt this to the new Emerson ST75? I have included pics of the original and the new. The setting in the factory Trane is set to 3H /2C.
#2
Welcome to the forums.
Did you check that that thermostat will work in a dual fuel application.
I didn't see dual fuel in accepted system types.
Did you check that that thermostat will work in a dual fuel application.
I didn't see dual fuel in accepted system types.
#5
Hi, the specs say it is comparable with your system, however you will need a “C” common conductor from your AH , maybe on of the sensor wires can be repurposed for that option.
Geo🇺🇸
Geo🇺🇸
#6
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I have the blue wire as common, it seems to work in AC mode, just didn’t want to switch over to heat yet till I know the wiring is right. Plus it’s been kinda warm here to try the heat.
#7
The Sensi tech info is very convoluted. You must make sure there is a step in programming for dual fuel and then select that.
Your old stat used an outside temperature sensor to tell the heat pump to shut off and the furnace to come on. Your new stat uses online weather information.
Normally with a heat pump .,.,. the heat pump and the electric heat could/would work at the same time.
A furnace cannot run at the same time the heat pump is.
Your old stat used an outside temperature sensor to tell the heat pump to shut off and the furnace to come on. Your new stat uses online weather information.
Normally with a heat pump .,.,. the heat pump and the electric heat could/would work at the same time.
A furnace cannot run at the same time the heat pump is.
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That’s what I’m concerned about. I’m not too worried about not having the back up heat strips, since it uses the heat pump and furnace. I am concerned that if the heat pump is on and then it’s below a certain temp (40 on the old Tstat) and then the gas pack comes on I will destroy the system.
Right now it’s hooked up like this:
G - green
Y - yellow
C - blue
O/B - orange
RC - red (factory jumper in place, same as the original)
WE - white (no room in the terminal block for the white jumper wire that came with the new Emerson to go to the WE W2 connectors, if that’s where it would even go).
There is no option for anything else during setup. However I can go in the tstat and reconfigure my indoor and outdoor equipment ie. 1H/1C , 2H/2C, plus any combo of 1/2, don’t have the 3/2 like the old one.
during setup I selected Gas as my heat.
Right now it’s hooked up like this:
G - green
Y - yellow
C - blue
O/B - orange
RC - red (factory jumper in place, same as the original)
WE - white (no room in the terminal block for the white jumper wire that came with the new Emerson to go to the WE W2 connectors, if that’s where it would even go).
There is no option for anything else during setup. However I can go in the tstat and reconfigure my indoor and outdoor equipment ie. 1H/1C , 2H/2C, plus any combo of 1/2, don’t have the 3/2 like the old one.
during setup I selected Gas as my heat.
#9
I haven't found an actual programming manual. Just tips and mentions of the app.
You have a heat pump with backup gas furnace.
You don't program as a gas furnace system. .
You have a heat pump with backup gas furnace.
You don't program as a gas furnace system. .
#13
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X2 on the original, would that be for emergency heat? By placing the jumper there the gas heat kicks on when there is a call for aux/emergency heat?
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No clue caddy, won’t the heat strips come on as well is the emerg call is made and it would run them along with the gas? Looking at the unit wiring, they are only using R, C, G, Y, W, O wires
#15
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I'm not sure how the packaged units operate or are built, I just know for my own dual fuel system (split) there are no electric strips. The heat pump works until it either needs a defrost or it is too cold, then the gas kicks in. My gas is a two stage system, but the main board handles the 2nd stage (I assume via time/other programming), so there is only one wire from the thermostat to the air handler to tell the gas heat to turn on. Which is why I question of the jumper was there to kick on the gas when either the 2nd stage was needed or when aux/emerg was called upon.
#16
I would imagine the indoor equipment is GA1 - gas single stage.
You do not have heat strips. Your backup heat is the furnace.
Your new wiring looks correct.
You should try to clean to the wiring so there is not so much copper wire exposed.
You don't want any shorts.
You do not have heat strips. Your backup heat is the furnace.
Your new wiring looks correct.
You should try to clean to the wiring so there is not so much copper wire exposed.
You don't want any shorts.
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I’d love to but don’t have any spare wire in the wall to work with. Probably have to get some colored electrical tape. Right now the settings are on HP2/GA1. Just can’t figure why the trane one was set to 3H/2C
#18
I don't know but 2C is also incorrect. It may not make a difference if the terminals aren't used.