Trane TCONT803 Replacement


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Old 05-17-14, 06:48 AM
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Trane TCONT803 Replacement

The touch screen on my 6 year old TCONT803 has stopped working. Even though it is covered under the "10 year" warranty by Trane, the company that did the original installation wants to charge me over $300 to replace it. I figured for less than that I could buy a new thermostat and replace it myself.

Here is what I have
Trane 4TWX6036 heat pump (XL16i)
Trane 4TEE3F40 air handler
Trane TCONT803 tstat

The system has a 5kw heat strip for "emergency heat". It has a two stage cooling system where the fan speed drops down when the temp is close to the setpoint.

The following wire are connected to the back panel of the tstat housing:
Y2 (black)
W1 (white)
R (red)
O (orange)
Y (yellow)
G (green)
B (blue)
R is jumpered to RC with a small piece of wire.

Is there a suitable replacement for this thermostat that will be easy for me to install, maintain the features (two-stage cooling particularly), and be less expensive.

Thank you in advance for any help you can provide.
Best regards
Mike M.
 
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Old 05-18-14, 07:45 PM
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TH8320WF1029 Honeywell WI FI Touchscreen Programmable Digital Thermostat - Programmable Household Thermostats - Amazon.com

The Honeywell TH8320WF would be a good choice for your system. It is one step up from the model that you have since it has WiFi capability.

When something that I own breaks I usually look into upgrading options since you can factor in the cost of an exact replacement (TH8320) and see that the upgrade isn't very much money.

Amazon has it for $141.00
https://customer.honeywell.com/resou...69-2733EFS.pdf

Your old B terminal will be a C terminal on any new thermostat.
 
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Old 05-19-14, 12:04 PM
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Thanks Houston! I appreciate the feedback.

The mounting plate and connector from the Honeywell looks almost identical to the Trane.

The one major difference is that I have a white wire in a slot currently labeled W1. That same slot on the Honeywell is labeled K. I think my wire is for aux heat, so should it go in slot E/aux on the Honeywell? Is that one of the little differences they made to make the Trane "incompatible" with a standard Honeywell?

Again, thanks so much for your advice!
Best regards,
Mike M.
 
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Old 05-20-14, 11:05 AM
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The problem that many posters seem to have is the B terminal on Trane thermostats is common. When they connect the old B to the B terminal on any thermostat that isn't a Trane it pops the fuse.

Remember to turn off power to the indoor unit before replacing the stat.

There is a common mistake made when people wire the air handler on that setup if it isn't the model with the marquee.
 
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Old 05-23-14, 11:33 AM
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Everything seems straightforward, but I do have a question.
My Trane thermostat has a single white wire going to W1, which I think is supposed to turn on the heat strip for emergency heat. I assume then that for the Honeywell, I will have to move that wire up one notch to the E/AUX connection. Correct?

It looks to me like all the other wires are in the exact same place.

I just want to be careful and do this right. I'd hate to break my a/c now that it's getting really hot outside.

Thanks again for your assistance.
 
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Old 05-23-14, 11:44 AM
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I will have to move that wire up one notch to the E/AUX connection. Correct?
I believe that is correct. It won't blow the fuse or hurt anything if incorrect.
 
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Old 05-23-14, 12:00 PM
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Yes, W1 will now be Aux/E.
The new thermostat will require function 170 to be set to 11 to control your 2 speed heat pump with Aux heat application.
 
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Old 05-23-14, 12:58 PM
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Thanks guys.

Can you explain the difference between function 170 set at 11 and set at 8? Does it have to do with the heat pump needing to drive the Orange reversal valve wire?

Just out of curiosity, if I'm in a pinch and want to bypass the thermostat and turn my a/c on, can I just jumper wires with the tstat removed?

Would it be R-O-Y-Y2-G all connected together? (just curious, I don't plan on trying this)
 
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Old 05-23-14, 01:10 PM
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Setting function 170 to 8 would not run the compressor for heating. It would only run the heat strip.

Yes, R-O-Y-Y2-G all connect together for high speed cooling.
 
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Old 06-24-14, 11:59 AM
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Sorry for the delay, but I've been dragging my feet over this swap. I've been reading the Honeywell document, and I had a question about the test sequence.

Page 9 shows the test modes. I assume that I should cycle through each mode and verify that the system is behaving the way it should.

Cooling system shows 3 modes,
1) compressor and fan off
2) compressor and fan turn on
3) second stage compressor turns on

When I go from #2 to #3, should my air handler fan speed change too? Should I hear my compressor sound change as the 2nd stage kicks in?

Also, on the heating tests, I'm not sure what to expect. It shows two different tests, "Heat" and "Emergency Heat". When I run through the "Heat" tests, should I expect the two different heatpump levels with corresponding air handler fan speeds?

Is "Emergency Heat" my heatstrip heater? If so, what is "second stage emergency heat"?

Sorry for all the questions, but I want to make sure that when I put this together that everything is working.
Thanks!
Mike M.
 
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Old 06-24-14, 12:28 PM
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I use a clamp on amp meter to determine if I am in High or Low speed and I write both readings and the outdoor temperature in the heat pump electrical panel. You can hear a small shift in the noise if there when it occurs but not if you walk away while it shifts.

I can't help you much on the rest of your question.
I never use the test function to prove operation. I would rather give the stat different demands in operation mode to test.
 
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Old 06-25-14, 03:49 AM
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Thanks Houston.
Maybe I should have asked my question differently. I know that the thermostat controls the air handler and compressor by sending different 24vac signals to it. What I'm trying to figure out is which signals are sent during which mode. From what I understand, the modes I have are:

low cool
high cool
heat (heat pump)
heat (heat strip)
fan

I'm not sure if I have two levels of "heat pump" heat. I know I have two levels of cooling.

For outputs from the thermostat, I have:

G Green fan?
Y Yellow compressor?
Y2 Black compressor 2nd stage?
O Orange reversing valve?
W1 White Heat???

What I'd like to know is which of these control signals will have 24vac on them during the different modes of operation. That way I can put a volt meter on them and verify what the new thermostat is trying to do, and check that against what is actually happening with the system.

Sorry for all the questions... I'm just trying to get a good understanding of what I'm doing and how it works.

Best regards and thanks!
Mike M.
 
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Old 06-25-14, 05:48 AM
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Yes, you have 2 stages of heat from the heat pump and the electric heat strip gives you a third stage of heat.
The O terminal is not energized in heat mode.

You have correctly identified the terminals in your last post.

W1 is heat strip and B is common.
Measure for 24 volts between the other terminals and B for a signal from the stat.

When the stat is correctly calling for High or low stage the operation should be verified outside. I have often had to correct a wire connection to get high speed.
 
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Old 06-26-14, 10:45 AM
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I installed the Honeywell VisionPRO 8000 ( TH8320WF1029 ) this morning to replace the failed Trane TCONT803. Everything is working perfectly. I wanted to post a follow-up just in case someone else was looking for details on the replacement.

Even though the mounting plates look very similar, they are not the same. I originally thought I could leave the Trane mounting plate in place, but the Honeywell won't mount up to the Trane mounting plate.

The wiring is almost identical between the Trane and the Honeywell. The only wire that was different was the W1 on the Trane moved to E/AUX on the Honeywell. Here is the old to new wiring:

TCONT803 Color Honeywell
RC/R Red RC/R jumpered together from factory
O Orange O/B
Y Yellow Y
G Green G
B Blue C
Y2 Black Y2
W1 White E/AUX

If anyone is looking for more details about how each signal works, read on.

The thermostat is supplied with 24 volts AC power from the air handler on the Red and Blue wires (RC/R and C terminals). The Blue (C) terminal is common. The thermostat switches this 24 volts AC to engage different functions in the air handler and compressor. Here is a table with each mode and the corresponding outputs. A 0 (zero) means no 24 volts and a 1 (one) means 24 volts is being supplied to that terminal by the thermostat. My unit is a 2 cool and 3 heat cycle unit. Yours may be different.

O/B Y G Y2 E/Aux
Standby 1 0 0 0 0
Low cool 1 1 1 0 0
High cool 1 1 1 1 0
Fan only 1 0 1 0 0
low heat 0 1 1 0 0
high heat 0 1 1 1 0
Em heat 0 1 1 1 1
heat strip 0 0 1 0 1

Sorry about the column alignment.

PLEASE power down your system before replacing the thermostat, and read all the directions that come with the new one. It could save you a lot of time (and money).

Good luck
Mike M.
 
 

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