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chaaalie 11-30-2010 10:34 PM

Trane TCONT803 Tstat install ... on Trane XB14 system
Okay, I think I have this right, but reading the install instructions has me second-guessing myself.

Had a pretty generic t-stat with the Trane XB14 Heat Pump system we had installed last year, and it had the following wires:
C (Cyan) - Common
R (red) - Power
Y - (Yellow) - Cooling
W - (White) - Aux/Emer Heat
G - (Green) - Fan
O - (Orange) - Reverse Valve (energize to cool)
(There was also an OPEN terminal "B" labeled Reverse Valve - Energize to heat.)

The new Trane TCONT803 I am installing has MANY more options ... but here is how I crossed them:
C (Cyan) - Common -------------TO B TERMINAL
R (red) - Power -----------------TO R TERMINAL
Y - (Yellow) - Cooling -----------TO Y TERMINAL
W - (White) - Aux/Emer Heat --TO X2 TERMINAL ** or should it be W1? **
G - (Green) - Fan ----------------TO G TERMINAL
O - (Orange) - Reverse Valve --TO O TERMINAL

The issue is that I read on p. 18 of the install instructions (regarding Advanced Features/Special Heat Pump Features):

"The first stage of heat is whatever is connected to the X2 terminal. The second stage of heat is connected to the W1 terminal. Usually the emergency and auxiliary heat sources are electric strip heat in these cases."

Now, this is where I was confused -- when I initially installed it, I put the white wire (W) on the W1 Terminal, but in the heating tests nothing seemed to happen. (If this system uses the Orange/Reverse Valve "energize to cool" shouldn't the Aux/Emergency heat be on X1 rather than W1? Because the actual stage 1 of heat is the compressor running without the Orange lead energized -- right?)

In testing mode, it seems to work now (i.e. the electric heating strips came on when testing the emergency heat option) -- but it is hard to test the heat pump's actual heat output (primary heat), as it is 80F outside right now -- at 10:30 p.m., just an hour and a half away from December (I'm in central Florida.)

hvactech126 11-30-2010 11:16 PM

first stage of heat is sending 24 volts to g and y this is your heat pump. how many stages of aux heat do you have? if only 1 stage of aux, then jumper w1 and x2

chaaalie 11-30-2010 11:40 PM

Thanks for the response ... I'll look at the various wiring diagram options and see if any show adding a jumper there ... If the coils are working, what do I need from W1? Additional voltage?

I'm just 2 stages (one Aux) ... First from the heat pump itself, then the aux/emergency heat from the electric heating strips.

When testing "heat" (stage 1) it did cycle the compressor (although with an outside temp of 80 I didn't expect much "heat recovery" -- air temp at vents was neither particularly warm or cool.)

Then, testing aux/emergency heat setting I could immediately smell the dust burn off the electric strips and the air temp at vents was clearly warmer.

I want to make sure this is right ... Overnight temps tomorrow night will be about 40 degrees cooler!

hvactech126 11-30-2010 11:47 PM

i think you are right, but not saying it correctly, first stage is primary heating ie heat pump, aux is second stage ie electric strip and also your emergency heat. jumper w1 and x2 together your aux or second stage heat is the emergency heat

chaaalie 12-01-2010 12:13 AM

I don't doubt that I am saying it wrong! :thumbsup:

I did find a reference to jumpering the two (but it is only mentioned in a section that deals with an outdoor temperature sensor and a Fossil Fuel Option as backup heat.) Being in Florida, these are things we simply don't have (the outdoor temperature sensor is just so that the system will automatically lock out the compressor when the temperature drops below the "balance point" -- right?

On some of the diagrams though, I did notice that the leads from X2 and W1 were apparently "jumpered" away from the actual thermostat (presumably the diagram was representing the wiring that all seems to meet in a "control panel" of sorts on the air handler) ... the diagram I had been using shows some sort of switch between the connections at the other end of the X2 and W1 leads. It is FIG 9 on p 4 of the PDF at HERE which is listed as "Typical hookup of single-stage heat pump with auxiliary/backup heat (2H/1C heat pump)."

The issue at hand was that digram shows connections for 7 wires/terminals (after you discount the 2 connections for the outdoor temp sensor I don't have) ... and I only have the 6 leads I mentioned at the outset. With the extra lead being either W1 or X2!

hvactech126 12-01-2010 07:36 AM

right! So, your back up heating is only one stage, so jumper w1 and x2 and have your white wire to that as well

beenthere 12-01-2010 06:13 PM

You can jumper X2 and W1. Shouldn't make a difference though. As long as you have your white wire on X2.

The diagram you should be using is fig 11.

As long as you have the white on X2(or jumpered to it) it will work though.

chaaalie 12-01-2010 06:30 PM

Ahhh! Now that the temperature is already about 25 degrees lower than yesterday, the need for the jumper makes more sense to me (in part because I can actually run the heating cycle and see how it is supposed to work!)

I didn't realize that the thermostat wants to use the electric heat strips to supplement the heating of the heat pump (calling it "Auxiliary Heat" -- which has to be the W1 lead) if the actual temperature and the set temperature are too far apart .... and then the electric strips themselves serve as "Emergency" heat source (no compressor -- whether locked out or not) which obviously is the X2 lead.

I'm usually not this dense, but I am still learning about how the whole Heat Pump system is supposed to work -- and this thermostat is significantly more complicated (powerful?) than the rather simple model it is replacing!

Thanks guys for your assistance on this. Great forum!

kkhoang 09-07-2011 10:56 PM

I'm looking for an Outdoor Temperature sensor to use with the Trane TCONT803 thermostat. I've searched all over the internet but could not find one. Do Anyone know the sites that have it?
Thank you,

beenthere 09-08-2011 05:39 AM

Tcon thermostat is made by Honeywell.

kkhoang 09-08-2011 07:56 AM

Thank you very much. Great site! Great forum!

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