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RCS Z-Wave Thermostat -- great new design!

ChrisWalker

Active Member
We just got a new RCS thermostat in yesterday for the lab. I was expecting to have to find an AC plug, etc. but...

The thermostat and Z-Wave module is now powered by the AC unit itself!

So now, instead of plugging it in (and having to find an outlet near the AC unit), it uses the 24V AC power.

Pretty nifty. Great job, RCS.

Chris
 

electron

Administrator
Staff member
I didn't realize you had to have an extra outlet before. Do you have any pictures of this new thermostat?
 

Tombo

Member
It should have been designed that way to begin with. A thermostat that needs 120v plug is stupid. I would not compliment them for doing it the right way now. It is like telling Microsoft they have done a great job for coming out with a service pack that fixed bugs they had in their software.
 

Micah

Active Member
C'mon Tombo, tell us how you really feel. ;)

I never realized the first gen RCS Thermostat needed 120V to work. I was going to purchase one a while ago but held off for various reasons. Sounds like I may need to take another look at it now that they improved the design.
 

Guy Lavoie

Active Member
Actually, for a communicating thermostat I wish it did use a seperate power source other then the furnace. This is because the thermostat could then be powered through a UPS. When your UPS protected automation system is exchanging information with a thermostat that suddenly goes dead due to a power glitch, funny things can happen. I've had a garbled termostat response hang the communications once.
 

WayneW

Senior Member
And some HVAC systems are not able to supply a stable or sufficient enough power to reliably operate the stat and people have to add aux 24VAC transformers anyway. Cannot please everybody ;)
 

ChrisWalker

Active Member
As a quick note, we wired up the thermostat with a 24V AC power transformer from Radio Shack for test purposes. I'm not sure if you can do that _and_ hook it up to the HVAC unit, but it seems to like it fine.

Chris
 

Squintz

Senior Member
Does it heat up and get warm like the ACT HomePro ZTT000 Thermostat. The biggest issue I have with my z-wave thermostat is that it uses 24vAC power right from the AC when in reality it only requires 5volts or less DC to run the thing. If you check out most programmable thermostats they are powered with a few "AA" batteries. When using 24vAC the unused power is disipated in the form of heat right at the thermostat which causes the thermostat reading to be inaccurate at times.

Does the RCS do this?
 

MeSteve

Member
I would guess not since the temperature reading part (box on the wall) and the part where I would imagine the voltage regulation (box near the furnace) happen are two separate locations. Just a guess.
 

Digger

Senior Member
if the thermostat was powered by the 24 Vac but had a battery backup then it would be ideal.

Actually you can put a UPS on the furnace control circuit since it doesnt pull much power. In my house I can just replace the small Class 2 transformer that is mounted on an electrical box with a 24 Vac wall wart that has an equal or greater current rating and I would be set. Plug the wall wart into the UPS and its backed up the controls.
 

az1324

Senior Member
MeSteve said:
I would guess not since the temperature reading part (box on the wall) and the part where I would imagine the voltage regulation (box near the furnace) happen are two separate locations. Just a guess.
The digital logic chips are not running on 24VAC, though. So at the thermostat, the 24VAC is converted to 5VDC and/or 3.3VDC using a voltage regulator which will generate heat. It don't know how much power it uses, but with an RF chipset it definitely is a design consideration.
 
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