[Release] HVAC Zoning & Ventilation Control

The HVAC Zoning App for Hubitat controls a Heating, Ventilation, and Air Conditioning system.

  • Single and Two-stage Forced Air Heating and Cooling Equipment
  • Zoned and Non-zoned duct systems, including systems with controllable registers and duct fans
  • Ventilation equipment, including ventilation equipment that utilizes the blower.

This is the first release of this software. I have tested it using a simulation environment with virtual thermostats because I have not been able to get useful signals from my Emerson Sensi thermostats. I am hoping some people will test it with other types of thermostats. Due to the lack of testing to date, I recommend that people set it up in a shadow mode for awhile before trusting it to control your HVAC system. By shadow mode, I mean setting up a dashboard to see what it would be commanding in different situations and make sure that it is reasonable for various situations.

You need to install three Apps:
https://raw.githubusercontent.com/rbaldwi3/HVAC/master/HVAC_Zoning.groovy
https://raw.githubusercontent.com/rbaldwi3/HVAC/master/HVAC_Zone.groovy
https://raw.githubusercontent.com/rbaldwi3/HVAC/master/HVAC_SubZone.groovy
PDF documentation is at: HVAC/HVAC Zoning App.pdf at master · rbaldwi3/HVAC · GitHub

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I saw you released this in May but I'm shocked to see no responses. How has this been working for you?

This is something I've been interested in for a while. I currently have a motorized damper tied to a Zwave Module that I use to open and close the damper in my office. I was thinking about doing it for the rest of the house as the HVAC system in my house was set up really funky.

I have been continuing to refine the software and have been using it to control the HVAC system in my house for the last couple months. My house has four zones but doesn't have any controllable registers, so I am still relying on a test environment with virtual devices to test the subzone features. I have also been testing thermostats. I hope to have a new version to release in the next month.

Same surprise here, I don't think I would have seen this except for @JoshFink's post.

We are doing some work to the house in the future and I'd like to throw in some HVAC upgrades at the same time. Currently unzoned/single-trunk "dumb" system w/manual registers. Would like to add duct fans (which I just found out about, very cool!) and controllable registers, and maybe go to two zones. Our most commonly occupied room in the house, our family room, is also the room farthest from our HVAC closet. Based on your PDF, a two-zone ducted HVAC system might be our goal. House is not huge, a little over 2k sqft.

We have lots of imbalance in our current HVAC system, always heating one area too high, or cooling one area too much, to keep the other areas comfortable, and running around closing/opening vents. I'd really like to smooth things out, and make our HVAC use more efficient. This looks like it could be very useful for that.

I have a Honeywell T6 Zwave thermostat that I'm going to swap for my current Nest, but am waiting for a promised (HE staff) app coming in 2.2.4 that will allow me to use external temperature sensors (motion sensors, mostly) to manage the HVAC system through my T6. It sounds like your system is already able to do that. Is that correct?

Off to read your documentaion PDF. :slight_smile:

I'm not sure exactly what you mean by managing the HVAC system through the thermostat. My system takes input from a thermostat and relies on something like a Zooz ZEN16 multirelay to convey control decisions to the HVAC system. My software requires a thermostat for main zones (of which there must be at least one). A virtual thermostat with temperature from a temperature sensor counts. For subzones (controllable registers or duct fans), my system requires either a thermostat or a temperature sensor.

I have not tested the Honeywell T6 or Nest for compatibility yet. What my software needs from the thermostat is prompt and reliable updating of the thermostat operating state (heat call, cooling call, idle) to Hubitat. The ZWave and Zigbee thermostats that I have tested so far pass this test. The cloud thermostats that I have tested so far (Ecobee and Emerson Sensi) have failed this test.

OK, great, thanks for clarifying.

So you take heat/cool/fan calls from the thermostat (virtual or physical) and use that info to feed instructions the HVAC system via ZEN16 or similar.

What I'm looking for is a system that allows manual control/override at the thermostat (wife "must" requirement) along w/the automation. Would that be available w/your system? Seems like the answer is yes, my wife raises the cooling set-point on the thermostat and your system would react/implement. Victory all around.

I'm sorry, but family got in the way so I haven't been able to read more than a few pages of your amazingly detailed documentation (impressive). In your setup, is the ZEN16 connected directly between the thermostat and the HVAC system?

That is an accurate description.

I consider changing setpoints at the thermostat to be normal operation. The ability to change them remotely or via an automation are additional options which you can choose to use or not. Of course, if you choose to use a virtual thermostat for some portion of the house, then there would be no physical device at which to change that setpoint. But, the portion of the house controlled via the Honeywell T6 would respond to changed made through the physical device.

I don't know what you were doing with your family, but I strongly suspect it was much more important than reading my document. We can't lose sight of what is really important.

There are a variety of way to connect things, depending on the characteristics of your duct system and how much control you are comfortable giving to the Hubitat App. The fact that there are many options is much of the reason that my document got so long. One option is to set them up with a "wired or" such that the equipment goes on when either the thermostat commands it or the App commands it. That way, the system continues to function normally if you lose ZWave communication, Hubitat gets stuck in an update, etc.

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I just released version 0.2. It is available from my Github repository.

The majority of the changes are restructuring of code to make it more robust. I did make a few changes to what control options are available for selecting zones and subzones in response to cooling and heating calls.

Probably the most significant accomplishment since the initial release is that I have been using this to control the HVAC system in my own house for a couple months. That gives me more confidence encouraging others to try it.

I have also done some thermostat testing. I have found two thermostats that work at least acceptably: Zen and Radio CT100. I have a GoControl thermostat ordered that I will test soon. There are many that I haven't tested. I have also found two ways to get the necessary information from other thermostats, as described in the documentation.

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It is now available via Hubitat Package Manager using the Climate Control tag.

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Could you do me a favor while you are waiting to swap your thermostat? Could you put batteries in it, include it on your Hubitat HE, and do some bench testing. What I am interested in is how quickly it reports operating state changes over ZWave. Preferably, check both operating state changes that result from setpoint changes and operating state changes that result from temperature changes. (Some thermostats are prompt with the former type but slow on the later type.) How quickly it reports temperature changes is also of interest, but much less critical.

Happy to do some testing, I've had batteries in it and set it up in HE a few weeks ago when it arrived. Can you confirm how you'd like me to test the T6...I'm assuming:

  1. Set point changes: Change the set point to a level that causes a state change (no action to cool or heat) and see how quickly that change appears in HE
  2. Temperature changes: Set points fixed, change ambient temperature (easy to do, I can just take the thermostat outside) and see how quickly the state change on the T6 shows up in HE.

That about right? Anything else?

That's about right. For point 2, I have had to modify my testing procedures a little for each different thermostat because they display slightly different information. One of them actually indicates on the display when it is calling for cooling, so it was easy to check whether that information showed up in HE at the same time. For others, I made a simple circuit with a battery and an LED to light the LED when it called for cooling via the wired interface. I'm not familiar with the T6 to know whether it displays cooling calls.

Hearing the audible click is also a good way to know when the cooling call started.

Just did test #1 for changing set point. Moved set point for cooling below current registered temp on the thermostat and between 2 and 3s after the thermostat "click" indicating change to cooling, the change to cooling mode registerd on the T6 device page. Seemed very quick to me! Did the change a couple of times and it was consistent.

Test #2 next. Test 2 results...the response on the T6 device page was almost instantaneous...when the thermostat went from heating mode to off (display changed and "click") the device page updated was updated as soon as I looked over at it. Really fast.

So:

Set Point change: 2-3s
Temperature change: almost immediate

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One thing that surprised me (and maybe it shouldn't have) is how s-l-o-w-l-y the T6 temperature reading changed when I moved it from the house to out front where it was 10 degrees colder (68 vs. 78). It must have taken 10 minutes for the T6 reading to fall to 70.

I assume that's intentionally throttled so your thermostat doesn't jerk your HVAC system around if the front door a window is open for a bit and a blast of cool air comes by.

Thank you. I will add the T6 to my list of successfully tested thermostats.
Also, my GoControl thermostat arrived last night and I have confirmed that it works well for this application.

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