any special wiring required for Omnistat?

[charliebarns]

I'm still in the pre-wiring stage of my home automation/security/network/CCTV etc. Yesterday an HA guy in the city here told me to make sure I pull 18/2 for 24V to the back of the Omnistat2. I had already planned a cat5 to that location, but do I also need to pull 18/2? I mean, there is already a 10 conductor wire there for the thermostat the HVAC guys plan on installing (I'll swap it out later). I would assume that 24V is a standard most Tstats use no?

thx

CB

 

[RArbour]

24VAC is standard for the majority of thermostats, but not all. There are a few thermostats that serially communicate with the HVAC controller. These thermostats do not require a high gauge since they are not trying to drive an HVAC relay from across the house. If this is the case, the Omnistat2 will not work with that HVAC controller.

If the installers are running a 10 wire to a standard 24VAC thermostat, there should be no reason to run additional wire. The Omnistat2 requires 3 (4 for rs232) wires for communication in which the cat5 will suit. You may want to verify that one of the 10 wires is a common (most probable with 10 wires). The Omnistat2 does not require a common, but may be limited without one (backlight may not be as bright).

Find out what gauge the 10 wire is and that should answer most your questions

Ryan

 

[ysualum]

While we're on the topic of Omnistats, I had another question. We have wired in 8 conductor wire and a cat5e to each thermostat location. We will be having 3 two stage variable speed AC/furnace units split into 9 zones . I plan on connecting the omnistat2s to Honeywell Zone controllers (Models HZ322K and HZ432K). Can you confirm this setup should work okay. Since the zone controllers can't manage humidity, I plan on having one stat in each zone wired directly to the humidifier.

Thanks and sorry to hijack the thread.

Prashant

24VAC is standard for the majority of thermostats, but not all. There are a few thermostats that serially communicate with the HVAC controller. These thermostats do not require a high gauge since they are not trying to drive an HVAC relay from across the house. If this is the case, the Omnistat2 will not work with that HVAC controller.

If the installers are running a 10 wire to a standard 24VAC thermostat, there should be no reason to run additional wire. The Omnistat2 requires 3 (4 for rs232) wires for communication in which the cat5 will suit. You may want to verify that one of the 10 wires is a common (most probable with 10 wires). The Omnistat2 does not require a common, but may be limited without one (backlight may not be as bright).

Find out what gauge the 10 wire is and that should answer most your questions

Ryan

 

[RArbour]

While we're on the topic of Omnistats, I had another question. We have wired in 8 conductor wire and a cat5e to each thermostat location. We will be having 3 two stage variable speed AC/furnace units split into 9 zones . I plan on connecting the omnistat2s to Honeywell Zone controllers (Models HZ322K and HZ432K). Can you confirm this setup should work okay. Since the zone controllers can't manage humidity, I plan on having one stat in each zone wired directly to the humidifier.

Thanks and sorry to hijack the thread.

Prashant

Prashant,
I looked at the specifications for HZ322K and HZ432K and cannot find anything that would not allow the OMNISTAT2 to work in this situation. From the limited information available it seems as if the Zone Controller is able to use just about any thermostat, just they recommend the Honeywell models for obvious reasons. I would wire the thermostat exactly like the diagram in the zone controller installation guide. We do not have any first hand knowledge of the Omnistat2 working or not working with these specific zone controller models (which may be a good thing since we are more likely to get calls about things not working, than things working).

The RC-2000 also has a mode called "Zone Control", which allows the thermostat to be setup as a master in the master/slave zone control configuration. This configuration is more prevalent in older systems and does not seem to be necessary in your Zone controller models.

Ryan