Do you own a CT100 Thermostat?


(Florian Z) #1

I installed a 2gig CT100 Thermostat, yesterday. It’s fully functional with SmartThings. However, it appears to be very sluggish in accepting commands. For example, when I tap the “Mode” tile in the SmartThings App, to cycle through the supported modes, it takes about 3 - 5 seconds for the next mode to be set and the UI to update. Same for fan control and the temperature setpoint sliders. I guess I was expecting performance similar to say the outlets and switches, which usually have a delay of < 1 second.

Are you seeing the same behavior, or is this specific to my setup?


(Minollo) #2

I have 5 of them; and yes, I see a similar behavior. It doesn’t really bother me, as I have apps taking care of controlling them, and I never access them manually… They have been working very reliably so far.


(Florian Z) #3

That’s good to know, @Minollo. Do you have yours wired up with the C wire?

I have a millivolt furnace, and no 24V power source - hence no C wire. The instruction manual says that in this setup, the zwave radio will go to sleep and not act as a signal repeater. I was wondering whether the sluggish behavior is possibly caused by the radio falling asleep.

I don’t care for the repeating capabilities, but could power the thermostat with an external power source, if that fixes the slowness. If the slowness persists with the C wire, then I’d rather not do the work. It’s slightly more involved in my case, because I have to separate the millivolt circuit from the 24V circuit and switch the furnace through a relay.


(Minollo) #4

Four of them have a similar setup to yours (no C wire); the fifth one is in a different location, where it controls a heat pump; and that one has power (C wire connected). I noticed no difference in behavior - even if I’m sure the non-powered ones are not acting as signal repeaters. Response times are equivalent.


(Florian Z) #5

Great. Thank YOU! You saved me a lot of work and subsequent disappointment :wink:


(Duncan) #6

Yes, it’s an unfortunate aspect of Z-Wave that battery-powered devices that need to receive commands are pretty slow. They have to be “beamed” for a full second to wake them up before the command, and to change the mode it takes one command to set the mode and another to check that it was set correctly.

I haven’t tested it, but it wouldn’t surprise me if the thermostat continues to act as a beamable sleepy device even when it’s powered from the wire.


(Curtmcgirt) #7

I have two of these thermostats, both powered through the C wire, and I’d classify the response time for both of them as ‘instantaneous.’