Unique thermostat setup at my house, I'd love some advice/input

My (split level) house requires 3 separate thermostats. I have 3 separate heating zones (boiler baseboard heat) as well as two separate Central AC units that are tied in with two of the 3 thermostats. Here are details:

  • Thermostat 1 = Located Upstairs - Heats upstairs, cools upstairs and downstairs for one side of the house.
  • Thermostat 2 = Located on the split side of the house - Heats and cools “split” side of the house
  • Thermostat 3 = Located Downstairs, below Thermostat 1 - Heats the downstairs area that Thermostat 1 cools.

As you can see, not only do I need 3 thermostats but I also have a unique situation where heating/cooling is handled via different thermostats for one area of my house (downstairs). I am not thrilled about the idea of spending ~$750 for Nest or Ecobee thermostats. I lean more toward using Zwave thermostats that will also allow me to more intelligently use remote sensors to make decisions about which rooms to care more about or use room/area temperature averaging. So, can I ask what you might suggest? It looks like 2Gig makes the popular CT100 Zwave thermostat – I can basically get 3 of those for the price of 1 Nest or Ecobee 3. Are there any other Zwave thermostats I should consider? Here are the possible setups I imagine:

  • 3 Zwave stats – Least expensive option and I can use my already-existing multi-purpose and motion sensors to read temperature throughout the house. This allows me to “care” more about the temperature of certain parts of the house at different times. This is especially important with my upstairs thermostat given that it cools both up and downstairs. It would be nice to be able to tell it to care more about downstairs during the day (right now I have no way to do this, all temp readings are taking upstairs)

  • 3 Ecobee 3 stats – Very expensive, but let’s me use remote sensors and have a thermostat system that can work indepdently of my ST hub. I’m not sure that’s worth $500 more though and the remote sensors are kind of redundant considering I have multis all over the house.

  • 3 Nest stats – Also very expensive and it’s not clear to me how well I could utilize remote sensors to make Nest “smarter” about my particular home setup. And I’m also not sure if Nest’s “learning” interferes with ST or vice-versa? Also hard to believe this would be worth $500 more.

I appreciate any and all thoughts/input! I think I know that Zwave stats are my best option, but I am open to any and all suggestions and would love to hear about anyone that has a similar setup.

Quick statements: All your choices are good because they are automated and work with ST! I would be most concerned about the interaction between therm 1 and 3 in general, even with dumb therms. They could easily “fight” each other. DON’T choose a narrow deadband, and be VERY careful trusting temperature measurements. Temps vary wildly depending on height above floor, drafts, location of vents, sun, calibration, device, etc etc etc. Don’t be scared, but be very deliberate and thoughtful so you don’t blow a bunch of money on one therm calling for heat, and one calling for cool at the same time. Your situation is an interesting challenge.

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Thanks for that feedback, and good thoughts. One thing I should have clarified, is that I don’t plan on ever using an “auto” mode of a thermostat to switch between heating/cooling on its own. I just don’t trust that. I fully intend to manually switch between heat/cool during the appropriate times of the year. In fact, I turn off the pilot light in my furnace during the late spring/summer/early fall months. I’m in the North East FWIW.

As for using secondary sensors, I totally get how they can be affected by other factors. I wouldn’t ever use one on a window or near a draft, for example, and I think it would be more prudent to use averaging. One nice thing with the zwave stats is that I could use the downstairs thermostat as a thermometer for making AC decisions, because that zone is controlled by the one upstairs.

@pranalli, I use 2 z-wave Evolve T100r’s to manage temperatures, along with a couple of SmartApps, motion detectors with temperature sensors (ST’s and PEQ’s), and presence devices all working together. One day I’ll also incorporate controllable vents in each room. These thermo’s can use external wired sensors if needed. The link shows the “H” version, but they are exactly the same - “r” stands for residential and “h” for hospitality.