2GIG or Trane Tstat and HyBrid/Dual Fuel Systems

Currently have a Trane Dual-Fuel setup (Heat Pump + Gas Furnace)… It’s currently paired with a Trane 830 Series Thermostat that provides some functionality that I would lose with either the 2GIG or Trane Thermostat… These are:

  1. System uses an outside Temp. sensor to disable the Heat Pump Compressor when the outside temperature drops below 40F (configurable variable).

  2. Thermostat will use the Compressor in the summer to maintain the humidity within 5% of a set point (provided the temp doesn’t go below a set Delta value from the set temperature.

It appears at first glance at the Installation/Operations manuals for the Trane Z-Wave TZ43 Thermostat that you can disable the Compressor or Aux Heat (Gas in my case) using a configuration variable. This would allow the thermostat to mimic the functionality of the Trane 830 series unit of disabling the compressor below certain outdoor temperatures although it appears that the outdoor temperature is not a Z-Wave readable variable so I would have to get the outdoor temperature from another source like the yet to be released Aeon Labs outdoor Multi-function motion sensor. Not sure what level of Luup coding would be required to implement that.

In terms of Humidity control, I don’t believe there is anything that Z-Wave could do to replicate the functionality of the Trane 830.

Any ideas on this would be great… I have one Dual-Fuel system currently but expect to be replacing the other aging unit in the next 2 years and would really like to control both with Z-Wave…

I had contacts RCS systems regarding the TZ43 (it’s manufacturer) but they have no plans to add any of this functionality to this Tstat…


I am running the Trane/Schlage TStats and my main furnace was a Heat Pump with Natural Gas Emergency heat. I have an older (~1998) Trane furnace that needed a third party fossil fuel kit to coordinate with the HP. Needless to say, it failed to cross over once the outdoor sensor hit the 40 degree cut-off and left the TStat confused and the house without Emergency heat. The Heat pump continued to try to run and the house never got above 65 degrees.

Problem was that the TStat was sending a false call for the HP and for Emergency Heat simultaneously and there is no setting in the TStat to configure this. I ended up pulling out the fossil fuel kit and just running the system as a furnace and A/C. Turns out the HP couldn’t keep up anyway so no great loss for me.


Once I have a measure of outdoor temperature, then I probably will get the RCS/Trane TZ43 Thermostat and see if I can manipulate the thermostat from Vera to enable/disable the HP/Gas Furnace based on Temp.

Still would be nice to have a Z-Wave tstat that does Humidity control as well since we are thinking of having a whole-house humidifier on the new system when we replace the aging one…

I am still trying to figure out how I will ‘fool’ the Trane Z-Wave unit into using Gas when temp is below 35F outside and HP when it’s above 35F. The stock therm. does that automatically (using outside sensor). I expect I will have to run a periodic scene or luup code that changes Trane TZ43 parameters to change it from a Heat Pump system to standard Gas furnace depending on outside temp (available from Google or soon to be installed HSM100).

The stock Trane uses the Aux Heat to run the Furnace so I expect any changeover equipment would already be there. I just need to figure out how to prevent the TZ43 from calling for HP when Aux Heat is needed…

One thing I thought of was to manipulate the Stage 1 (HP) and Stage 3 (Aux) delta settings via Z-Wave. If outside temp is below 35F, then set Stage 1 On delta to be 8F and Stage 3 On delta to be 1F. Above 35, it would be opposite.


I believe I have a solution but need some help from some Vera experts. The manipulation of the delta points for stage 1 and 3 didn’t work but then reading the manual for the Trane TZ43, I realized that they have the ‘EHEAT’ mode that essentially does what I want it to do. It uses the Aux. Heat and locks out the compressor.

The problem I have is the Thermostat Class in Vera only has OFF, HEAT, COOL and AUTO for its operating modes. EHEAT is not an option.

Is there a way to add this to the Thermostat Class in Vera2?

Has anyone figured this out?

I currently have a gas/ac setup, want to go to z-wave controlled dual fuel. I am not above hiring someone, but I get deer in headlights from my hvac guy…

The Trane instructions say I need a dual fuel kit - but I can find ZERO information on that online.

[quote=“haveitall, post:6, topic:167034”][Bump?]
Has anyone figured this out?

I currently have a gas/ac setup, want to go to z-wave controlled dual fuel. I am not above hiring someone, but I get deer in headlights from my hvac guy…

The Trane instructions say I need a dual fuel kit - but I can find ZERO information on that online.[/quote]
I replaced the Trane Supplied Thermostat on my Dual-Fuel system with the Trane Z-Wave and like I posted earlier, the EHeat mode does what is needed. I don’t believe you need a Dual-Fuel Kit - just wire the Trane Z-Wave in-place of the existing thermostat. I believe that I had a spare wire that wasn’t connected to the Z-Wave thermostat but didn’t appear to be needed.

The big issue is getting the EHeat mode into the Vera2 Thermostat Class (along with the Cycle Fan mode)… Once that is done, I believe I can use a recurring scene (every 15 minutes or so) to set EHeat mode or clear it, based on the outside temperature…

Sooooo… let’s do that. I just installed the thermostat.

(How do we do that?)

Still working through the EHEAT mode but above 35F, I have to set the Stage 3 On-Delta to the max. to keep the Gas from operating (assuming your delta from room temp to setpoint doesn’t exceed the max. diff). If you don’t set the Stage 3 Heat SP high, you have both Gas and Compressor operating at the same time.

The key when the outside temp drops below 35 is to set the Stage 3 On-Delta to be low (1) and then set the Thermostat Mode to EHEAT.

That sounds like a good theory. Two questions for you:

  1. Do you know of any reason why you shouldn’t run the compressor at the same time as the gas (which is what is going on right?)

  2. You change the on-delta with vera using an outdoor temp sensor? I will have to look into that - but is it some crazy parameter you figured out?

Thanks man - sounds like you worked it out!

I think that the compressor running at the same time as the furnace would not be good for the A/C system since I believe the evaporator coils come after the gaspack so you’d be heating the freon. Regardless, it would defeat the purpose of efficiency since in the colder temps, your Compressor is just wasting Watts without generating much heat…

The outside temperature is being monitor using the Google based plugin for Vera which is updated every 30 minutes I believe and taken from semi-local weather stations.

I also discovered that using the Delta-on values, I could prevent the Gas from running at the same time as the Compressor but not Vice-versa. EHeat mode is still needed to lock out the compressor. Hopefully someone at MicasaVerde can verify or even Add the EHEAT mode into the Vera package…

Unfortunately, there is not much information on whether the EHEAT mode is beyond the Z-Wave spec. or just a missing Vera/MIOS parameter.

Got it. That is the part I was missing - that the EHeat mode locks out the compressor.

I’ll give it a go!

The latter. There’s a lot that on the Trane that can be controlled through Z-Wave.

Formal feature request filed to expand thermostat functionality.

One more discovery which a) simplifies things but b) still requires the EHEAT mode…

You don’t have to change the Delta On values based on outside temperature but you do have to initially set all Delta-On values (but number 1) to 8. When you set HEAT mode, it uses the Delta-On 1 value.

For now, I have to manually set the Thermostat MODE to EHEAT based on the forecast temperature.