Omnistat2 Thermostat Pre-Wire

[broconne]

I am in the process of building a home - they have not broken ground yet, but I have a lot of the details worked out. This thread for details.

I have decided that I will be going with HAI for the security/automation panel. In case anyone at HAI wants to know why - it is because that you manufacturer and temperature and humidity sensors. (Sometimes it can be the little things)

For thermostats I want to use the Omnistat2 Thermostats. I will be installing them myself after I move in for cost and because the sub contractor had a fit when he found out I wouldn't want to keep the high end carrier thermostats.... Warranty voided, blah blah blah....

Anyway, that begs the question of how do I make sure I have the right stuff pre-wired to use an omnistat?

I will have two zones, at first, a zone on each the first and second floor.
Both zones will be hybrid heat - meaning there is a furnace and a heat pump. When the outside temperature drops below a certain point the furnace will kick on. I will not have a humidifier when I move in, but may add one to either of the zones depending on how humidity is that first winter.

Sadly, the heatpumps are all single speed - the extra cost to go a variable speed was way to much per unit.

I think I need to make sure that there is a "common" run to the thermostat and I guess two additional wires adding a humidifier in the future? Anything else I need to specify to the builder?

 

[PAPutzback]

I think these are the same questions I have asked in a thread last week. Another thing you have to worry about is if the wiring has enough power to run the stat. I here new wiring is supposed to carry enough voltage for the LED display and whatever else the unit used power for but some people have had to still buy the additional power supply that HAI sells. Also would the unit communicate with the OMNI controller via UPB over that common or do you have to run addition wires directly from the stat to the Omni controller?

 

[broconne]

I think these are the same questions I have asked in a thread last week. Another thing you have to worry about is if the wiring has enough power to run the stat. I here new wiring is supposed to carry enough voltage for the LED display and whatever else the unit used power for but some people have had to still buy the additional power supply that HAI sells. Also would the unit communicate with the OMNI controller via UPB over that common or do you have to run addition wires directly from the stat to the Omni controller?

Yep - I read your thread.. Which gave me the idea to make sure I had the humidifier pre-wire

I think the common carries the 24 VAC that the Omnipro needs. But not really sure - which is why I guess I started this thread

 

[RArbour]

Brocoone and PAputzback,
The Omnistat2 is pretty simple to wire.

First you need to run the standard HVAC wires (24VAC (from HVAC),Fan, comp, etc.). If possible I STRONGLY recommend running the common from the HVAC 24VAC transformer commonly found on the handler. The thermostat was designed to work without the common, but will not do so in all situations. Sometimes if this wire is missing, it requires an extra module to get it to work. The Omnistat2 controls an external humidifier by connecting the "H" output to the Rc (24VAC) when calling for humidity. This works for most humidifiers but you may want to consult your individual units to decide if you need anything extra.

If running a duel fuel (Brocoone sounds like you are), you will need the Omnistat2 to get the outside temperature some way. If you have an Omni with an outdoor temp sensor, it can get it that way. If not you need to run a two wire shielded cable to the Omnistat2 to connect an temperature sensor.


To connect with an Omni, 3 wires are need to directly run from the Omnistat2 to the Omni. This is not UPB and does not use the 24VAC.

Thanks,
Ryan

 

[broconne]

Brocoone and PAputzback,
The Omnistat2 is pretty simple to wire.

First you need to run the standard HVAC wires (24VAC (from HVAC),Fan, comp, etc.). If possible I STRONGLY recommend running the common from the HVAC 24VAC transformer commonly found on the handler. The thermostat was designed to work without the common, but will not do so in all situations. Sometimes if this wire is missing, it requires an extra module to get it to work. The Omnistat2 controls an external humidifier by connecting the "H" output to the Rc (24VAC) when calling for humidity. This works for most humidifiers but you may want to consult your individual units to decide if you need anything extra.

If running a duel fuel (Brocoone sounds like you are), you will need the Omnistat2 to get the outside temperature some way. If you have an Omni with an outdoor temp sensor, it can get it that way. If not you need to run a two wire shielded cable to the Omnistat2 to connect an temperature sensor.


To connect with an Omni, 3 wires are need to directly run from the Omnistat2 to the Omni. This is not UPB and does not use the 24VAC.

Thanks,
Ryan

Ryan -
I will be replacing the themostat they provide (my guess is a carrier edge) - so there will already be a outdoor temp sensor. Will the omnistat2 work with any outdoor temperature sensor? Or does it have to be a specific kind?

 

[ysualum]

We're in the process of getting our Omnistat2's installed. I had my sub run his 8 wire HVAC wire (not sure the gauge) which will accomodate any changes in the future. Had my LV guy run a cat5e for the same purpose, but I'll only be connecting 3 of the wires for now.

You can connect an external temperature sensor to each stat to average out the temps if you want, this may need to be run in advance as well.

FYI, we're having issues with the humidifiers. When the Omnistat triggers the humidifier it doesn't turn the fan on. This was confirmed to be correct when I spoke with Automated Outlet. I guess some stat's will do that. I'm planning on writing some rules that will make it turn the fan on as well.

 

[broconne]

We're in the process of getting our Omnistat2's installed. I had my sub run his 8 wire HVAC wire (not sure the gauge) which will accomodate any changes in the future. Had my LV guy run a cat5e for the same purpose, but I'll only be connecting 3 of the wires for now.

You can connect an external temperature sensor to each stat to average out the temps if you want, this may need to be run in advance as well.

FYI, we're having issues with the humidifiers. When the Omnistat triggers the humidifier it doesn't turn the fan on. This was confirmed to be correct when I spoke with Automated Outlet. I guess some stat's will do that. I'm planning on writing some rules that will make it turn the fan on as well.

Since I am doing a hybrid heat (duel fuel) system, an outdoor temperature sensor will be required. The manual for the omnistat2 does not seem to specify any specific temperature sensor - which is why I am wondering if any outdoor temperature sensor could be used? Do I need to pre-wire for a specific HAI sensor or can I use whichever sensor comes with the Carrier.

 

[RArbour]

broconne,
I am unaware of the specific thermistor that came with your carrier system. The Omnistat2 accepts a 10k thermistor as its external temperature sensor. Even if the Carrier sensor is a 10k thermistor, it may not calibrate correctly through all temperature ranges (This depends on other sensor parameters that are not commonly published).

Ryan

 

[broconne]

broconne,
I am unaware of the specific thermistor that came with your carrier system. The Omnistat2 accepts a 10k thermistor as its external temperature sensor. Even if the Carrier sensor is a 10k thermistor, it may not calibrate correctly through all temperature ranges (This depends on other sensor parameters that are not commonly published).

Ryan

Does HAI make a specific 10k thermistor for the Omnistat2? I was unable to find such an item.

 

[RArbour]

broconne,
Yes the temperature sensors are the same sensors for the original Omnistat series.

Surface Mount Remote Indoor Temp Sensor: 23A00-1
or
Flush Mount Remote Indoor Temp Sensor: 23A00-2

Ryan

 

[broconne]

broconne,
Yes the temperature sensors are the same sensors for the original Omnistat series.

Surface Mount Remote Indoor Temp Sensor: 23A00-1
or
Flush Mount Remote Indoor Temp Sensor: 23A00-2

Ryan

I seem to have confused things a bit, since you are mentioning two indoor temp sensors. A duel fuel system requires the ability to ascertain the exterior temperature. At a specific temperature point the system will switch from heat pump to natural gas. All duel fuel systems require this to operate. So the question is for that external temperature sensor do I need to prewire for a specific HAI temp external temperature sensor.


Thanks!

 

[RArbour]

Broconne,
My apologies, I was not thinking and was just copying text from an incorrect label of a product I had on my desk.

The 23A01-1 is rated for indoor and outdoor use.

Thanks,
Ryan

 

[dutchyn]

To connect with an Omni, 3 wires are need to directly run from the Omnistat2 to the Omni. This is not UPB and does not use the 24VAC.

To connect an Omnistat to an Elk needs four (4) wires, and a serial port on the Elk for each four thermostats.

 

[123]

...When the Omnistat triggers the humidifier it doesn't turn the fan on. ... I guess some stat's will do that. ..

I just encountered the same situation. My Robertshaw 9851i thermostat would activate the humidifier only if the fan was active whereas my new HAI Omnistat2 RC2000 will activate the Humidifier even if the Fan is inactive. It's a Desert Spring humidifer and it needs air flow in order to evaporate the water on its discs so I need to alter the Omnistat's operation.

I'd like the Humidifer to be activated only if the RC2000's "H" (Humidifier) AND "G" (Fan) terminals are enabled. I believe I need a relay that is powered by the "G" (Fan) line. When activated by the Fan line, the relay closes its contacts and allows for the Humidifier to be activated but only if the RC2000 activates its "H" (Humidifer) line. Does this make sense? Anyone see why it would not work?

The attached diagram shows how the RC2000 is currently connected and how it'd be wired with a relay.

 

[cornutt]

123, that looks like that should work OK. Get a relay that's rated for 24V on both the coil and the contacts. There's a possibility that it could activate the humidifier during cooling, which you probably would not want. You could do some fancier relay logic to prevent that, but it might be easier to just shut off the humidifier manually when the system is in cool mode.

One more thought: if you have your RC2000 connected to a controller, you could use the contacts of that relay to open or close a zone. Then you can write a rule that triggers on the zone, checks the thermostat mode, and turns the humidifier on or off.