Omnistat2 Hardwire vs ZigBee

[rsw686]

For those using the ZigBee version of the thermostat how do you like it? Do changes in temp update quickly and reliably? I've seen some posts about short range with ZigBee locks and bricked ZIMs after firmware updates. I'm hoping with the thermostat being powered by the HVAC the range will be significantly better.

In my setup the ZIM would be in the basement, the first thermostat on the main floor, and the second thermostat upstairs. The distance between the ZIM and first thermostat is about 15ft. The second thermostat is about 25ft from the first.

From what I can tell from reading the ZigBee thermostat is identical besides the radio. Are the hardwired terminals still there for the bus connection to the controller? If so this would allow me to cut open the drywall and run cables if I wasn't happy with the performance.

 

[lupinglade]

I believe they are indeed still there on the ZigBee model, since its identical with the exception of an *added* mini-board with the ZigBee radio. Even the firmware is the same I believe.

 

[HAI_fjh]

Yes you can still hardwire a ZigBee thermostat. As lupinglade noted the radio connects to a special radio connector on the back of the board and does not affect the normal serial interface.

 

[pete_c]

Fred,

Good news.

I always wondered if I could wire it serially and test it with Zigbee.

That was what really prevented me from buying it and a Zigbee controller a few months back.

 

[ano]

O.K. I'm putting in three RC-2000's with ZigBee, but the center location also has wiring from my previous Omnistat. If I hook up the wiring, does it turn off the ZigBee?  Does the ZigBee override the wiring?  Will having both wired and Zigbee cause any problems or does it offer any benefits?

 

[rsw686]

I ended up getting two of the ZigBee thermostats, which work great besides the time sync with the controller. From the reading I did the non ZigBee version has the same firmware minus the ZigBee radio module. In the PC Access software if the thermostat is using ZigBee you assign it the ZigBee ID. It sounds like you can hardwire the thermostat and pair it with the ZIM. However you need to pick your method of interfacing when setting it up in PC Access. HAI sells a standalone version of the ZIM so being able to hardwire and control the thermostat from the standalone controller makes sense.

 

[HAI_fjh]

I can not think of a practical reason for doing it but you can use both hard wire and ZigBee interfaces simultaneously. On my test system I have thermostat 1 set up as a hardwired thermostat. This thermostat also has a ZigBee radio in it. For testing purposes I defined a second thermostat, as a ZigBee thermostat and enrolled it. It is physically the same thermostat but the Omni sees it as two thermostats, one hardwired and the other ZigBee. All the readings are the same and if you change a set point via one interface it is reflected in the other.

This is a special setup for testing purposes. In the real world I can think of NO good reason for using both interfaces and IMHO having one thermostat look like two would just tend confuse some (porbably most) users.

IMHO if you can hard wire a thermostat it is best. It is simple and reliable. If wiring is a problem, the wireless is the next best solution. Wireless is also simple and reliable but again IMHO I generally prefer anything wired over wireless. I wouldn't go through a LOT of trouble to pull wire if I didn't have to but I do prefer hardwired stuff.

 

[ano]

I LOVE hardwired and haven't been a big ZigBee fan to date as the operation of my locks is still iffy, but this is why I forked out $50 extra for ZigBee thermostats:
 
I have spent the last two months working with four HVAC contractors to find one that would install a Zoned system that COULD BE CONTROLLED BY HAI.  The best I can tell Carrier doesn't still carry the Serial Interface Box that HAI can connect to, or maybe the contractors hate it so much it just doesn't exist in their minds.
 
So that leaves a whole lot of proprietary zoned systems that can't talk to HAI.  The only exception being the third-party controllers like Honeywell.  Trane and others have done this on purpose because they want to sell you THEIR Home Automation services, like Trane's is called Nexia.  YES it is clearly intentional that they won't talk to HAI.
 
So I went with the Honeywell system, but guess what?  Even their zone controller can use wireless thermostats also.  Their sales rep came to my house to try to sell it to me.  And what do you know, Honeywell is trying to sell home automation services as well.  Theirs is called "Total Connect." 
 
Luckily the Honeywell zone controller still supports WIRED thermostats like the OmniStat2.  With all these WIRELESS thermostat solutions out there, I can't describe the look on the AC installer's face when I told them, SORRY, YOU HAVE TO INSTALL THERMOSTAT WIRES because even though the OmniStat2 is WIRELESS in some ways, IT AIN'T WIRELESS IN ALL WAYS.  It took two AC guys almost 4 hours to install the thermostat wires.  They were in locations VERY hard to get to from the attic.  
 
So HAI/LEVITON, if you are reading this, I would highly recommend you start designing a thermostat that is 100% wireless, not just 50% wireless, if you expect to be controlling thermostats with the Omni a few years down the road.  The world is changing and the other guys are slowly but surely pushing you out of this business.  You also need to partner with folks at companies like Honeywell, so you will still have a shoe in the door.  In a few years, when you realize that you are no longer selling any OmniStats, read this post again if you want to know why. 

 

[rsw686]

I would not be a fan of a 100% wireless thermostat due to it needing to be battery powered. With the ZigBee thermostat the unit is still powered by the HVAC unit. Even if the ZigBee wireless stopped working the thermostat and HVAC unit would continue to function.

 

[ano]

Fan or not, this is the way the world is going.  Installers also don't like to spend their time putting in wires when in 5 minutes they can add wireless.  Zigbee supports low battery support, so just like how wireless alarm sensors report low battery, thermostats can also. 
 
I went with zoning for the simple fact that I have one room that gets a lot of sun and needs added cooling.  As it turns out, because its impossible to physically run a wire to this room, the best I could do it to have the thermostat in the next room, where it won't work as good.  Or I can run a wire from the thermostat to a remote temp sensor in that room.  Not pretty.
 
By the way, having a wireless thermostat doesn't prevent you from using wired if you want.