Just the Scheduler app works. When I did that with my T6, I discovered it was doing to good a job regulating+- 1/2 a degree which was causing a lot of hvac cycling. I could not find a hysteresis setting in the Thermostat menus. But the hubitat controller has it. So I added the controller then set hysteresis to 2 degrees. However the controller does get in the way of the wall mounted device but I made a dash board and it can be adjusted fine from that.
I had the opposite problem with the T6s, they were not regulating within 2 degrees either way, giving me big swings. Did you play with the cycles per hour setting in the driver? It didn't change anything for me to get a steadier temperature, but maybe it would going the other way.
I hate temp swings. I made a virtual thermostat controller myself to eliminate them using timed cycles and anticipation, as hysteresis is horrible for me. My driver does not over cycle.
Did you actually look at the temps with an external temp sensor? The screen on those lie, but since they don't show 1/2 degrees, I assume you must have used something external to determine that 1/2 degree. I run my heat now within a half degree (externally measured) that I could never get out of the T6s controlling temperature.
I did not play with the menus on the thermostat related to cycles per hour which I think is still 3. With just the scheduler, I was getting a lot of on off cycles compared to when I was on the Nest 3rd Gen. But indeed the temps did not swing much. I determined I could suffer a larger swing for less cycles so I put the controller back between the thermostat and the scheduler to allow another degree swing. True the display does not show 1/2 degree but the driver does so does the thermostat Apps. In the z-wave setting in the thermostat menu one can select 1/2 degree reporting. The default is 1 degree.
That Zwave setting makes the temps even more off base. I graphed these using external temp sensors, and there is some funny math going on in the Zwave reporting temp.
Everything is converted from Celsius. Without Zwave temps off, the thermostat will never read 74 degrees, as that value falls between rounding from C to F. With the Zwave temp setting on, it will read 74 degrees on the thermostat, but that temp is not accurate, certainly not to tenths of a degree. I'm not sure what the Zwave temp setting does to make F a decimal reading, but it can be over one degree off from actual, if you compare it to an external temp sensor.
23 C is 73.4,so the thermostat reads 73 with rounding. 24 C is 75.2, so thermostat reads 75 with rounding. I don't know how they get the decimal values for Zwave reporting, but it not based on actual temp at all. Their funny math will produce a decimal F reading that will round to 74, which allows the thermostat to read 74 on the screen in that mode only.
You really should compare Zwave reported decimal value it to a Zigbee temp sensor. You will be surprised how false that temp reading is.
This is one of the reasons why I eventually moved back to Nest thermostats. As much as I liked having full local control, I grew to not like having to use multiple temp sensors and thermostat controller to control my thermostats and get proper cooling and heating. I do, on occasion, like simply walking up to my thermostats to adjust the temperature. The T6s with thermostat controller, also limited my wife and kids from easily being able to adjust each thermostat. Yes, I have a tablet with a dashboard that they could have used, but they did not like not being able to simply set the temperature on each thermostat directly.
Yeah, I took control totally away from my three T6s, and replaced it with a Zigbee Relay board that controls the furnace zone valves directly from Hubitat, using a Virtual Thermostat driver with a controller app combo, and a Zigbee temp sensor for each zone.
My T6 controller app is the middle-man between the virtual thermostat and the Zone valves. It works with a virtual thermostat device to control the zone valves as is directed by the virtual thermostat device, without actually needing the T6 involved at all.
For control, I added the T6s to that app as well, so now the T6 controller uses the T6s as input and display panels only. Basically, it syncs everything both ways between the virtual thermostats and the physical T6 thermostats. It syncs mode, heating setpoint, and cooling setpoint if the other one is changed, but the T6s only have power wires, and do not control anything. They are still smart in that I have full local control over them by Zwave.
Using the temp offset command in the T6 driver, I found I could make the T6s read whatever temperature I wanted on the screen, within a three degree range from what it thinks the temperature is. I make the app always keep the T6 temp display to read the same temp as the rounded Zigbee temp sensor value that the virtual thermostat uses, by taking the difference between the virtual and physical reported thermo temps, and then adjusting the offset on the T6 by that amount, whenever the Zigbee temp changes, to keep the screen accurate(ish).
As a fail-safe in mid winter, I added a second non-smart relay board that switches any or all of the zone valves back to the physical thermostats, to put the T6s back in control if something fails on the Hubitat side, . Two winters now and not a single hiccup, and I have never needed to use the button on my dashboard or the physical disengage button, that flips all control back to the three T6s.
It was a fun coding project, and it has worked out well for my uses. Most of my time was spent messing around figuring out how to write the anticipating thermostat driver to actually control the furnace how I wanted.
1 Like
