Trane tz43 thermostat

[tjb1231]

I am having trouble installing my trane thermostat. I have a standard Gas furnace and AC. I have 4 wires coming from the furnace, red, white, yellow, and green. When i connect these wires to the new trane unit, it does not even power on. However, if i put the yellow wire in the 24 COM slot, the unit will power on but not control the AC.

bypassing the thermostat and touching the red and yellow wires together, the AC kicks on and the furnace blower turns on as well.

I had the thermostat working all winter for the heat with the yellow wire in the COM slot, but with that setup the AC will not turn on.

Can anybody help me connect this?

 

[ASIHome]

These thermostats (and all Z-Wave thermostats) require a common (usually Blue, but could be anything) to function.

Not always true but usually the colors follow as thus:

Red - 24VAC
White - Call for Heat
Yellow - Call for Cool
Green - Fan

You are missing this:

Blue - Common

The common is the other side of the 24VAC transformer. Most thermostats can steal enough power to function with only one side of the 24VAC transformer. Becuase of the communication circuit, the Z-Wave thermostats require the second 24VAC connection.

As I said above, the colors listed are in no way absolute. Please verify what you wire actually are.

 

[tjb1231]

These thermostats (and all Z-Wave thermostats) require a common (usually Blue, but could be anything) to function.

Not always true but usually the colors follow as thus:

Red - 24VAC
White - Call for Heat
Yellow - Call for Cool
Green - Fan

You are missing this:

Blue - Common

The common is the other side of the 24VAC transformer. Most thermostats can steal enough power to function with only one side of the 24VAC transformer. Becuase of the communication circuit, the Z-Wave thermostats require the second 24VAC connection.

As I said above, the colors listed are in no way absolute. Please verify what you wire actually are.

Thanks for the response. When looking at my furnace, only those previously stated wires are connected. There are 4 unused wires also in the same run of wires. I could simply use the unused blue wire but I am unsure of where to connect it to on my furnace. Could I use the same terminal where the red wire is going to? Just double up on it and on the t-stat side run that to the common?

Thanks

 

[ASIHome]

There is a terminal on the TZ43 marked "C" for common. On the HVAC side, you can see if there is a connection on the unit for "C" or go directly to the 24VAC transformer. Most 24VAC transformers have 2x terminals for Hot, you would take the "C" to the one that the "R" is not connected to.

 

[tjb1231]

There is a terminal on the TZ43 marked "C" for common. On the HVAC side, you can see if there is a connection on the unit for "C" or go directly to the 24VAC transformer. Most 24VAC transformers have 2x terminals for Hot, you would take the "C" to the one that the "R" is not connected to.

Well I connected to a terminal labeled C on the furnace to the 24 common on the thermostat. It lit up and controled the fan, but did not turn on the ac or heat. Then, after about 10 minutes it blew a 3 amp fuse on the furnace. I have not idea how to hook this thing up!

 

[WSeverino]

Another thing you can do is use a 24V wall-wart.

What Brand of furnace are you hooking up to?