Z Wave Thermostat

New to SmartThings and smart devices. My question is slightly involved.

My wife and I have a baby that’s a few months old, and live in Chicago area. So, it’s gotten pretty cold out lately. I have an ecobee3 thermostat, along with a sensor in each room. I have it programmed to go down to 64 at night - which, is too cold for the nursery. So, in an effort to combat that, I got a GE ZWave inwall smart plug and a good space heater. Then, through Stringify, I set up a few flows to turn on the space heater when it got below a set temperature, and turn off when it gets above another.

Except, the problem is that there can be a lag in time - seems it can be about 10 minutes (sometimes I’ve found 20) - between when the room gets to a certain temp, and when it gets updated to ecobee, SmartThings, and Stringify. Which means it can get cooler than you want it to, or warmer than you want it to, in that time. I like Stringify because I can set several conditions to certain things happening - like, someone is home in order to turn on the space heater.

But, I did find the Virtual Thermostat automation in SmartThings. Except, I’ve had a few problems with it. For instance, at about 1 am last night, it called to turn on the space heater because it got below the set point. And it did turn on. Except then the ecobee somehow went offline for a few hours. Because the temp did not get above the setpoint, the heater stayed on. I woke up at 4:30 to the nursery being 79 (nanny cam shows temp). Also, earlier today my wife and baby left Home while I was at work, and so the Mode switched to Away, such that the Virtual Thermostat wouldn’t operate because I have it set to operate only in Home mode. Except, when the wife returned home with the baby, and the mode switched to Home, the virtual thermostat didn’t kick on the space heater, even though the ecobee sensor was reporting it was below the set point.

I have a fix in mind: put a thermostat in the room that is WiFi so I can set it remotely as well as in the room. I can install a 24Vac transformer if need be in order to put in another ecobee if I want. What I then want to do is wire the thermostat wire (white, which calls for heat) to be wired to a ZWave relay. I was looking at the Ecolink door sensor because it has terminals. But I’ve also read where people have said that supplying voltage to it would fry it. Does anyone have any suggestions on how I could accomplish this? The idea is that the open/close of the ecolink sensor will register with SmartThings/Stringify nearly instantly, removing the ecobee sensor delay from the equation. I can then create a flow that says when the sensor is opened, to turn on the space heater, and then when closed turn it off, along with using my Presence virtual switch. Any help is greatly appreciated.

How you considered using a separate sensor which is more sensitive like a Monoprice or ZooZ 4-in-1 sensor which reports temperature in 0.1 degree increments? You can pair this with your Ecobee and then use a separate SmartApp to control it or use a different thermostat like a CT-101

This also has the advantage of running locally (depending what handler you choose), so your nursery should stay at temperature even if you lose your network connection, and you aren’t relying on any cloud-to-cloud integrations to remain operational.