Omnistat2 RC-2000 questions

[WayneW]

1) How noisy are the relays in the RC-2000? I realize this is pretty subjective, but some thermostats I have seen have pretty loud clicks and some are nearly silent. Obviously old mercury switch analog stats were dead silent, and I assume the communicating states that have the relays at the air handler.

2) How does the dehumidification control work? Does it just run the unit longer (extra cold) to get the humidity down) or does it signal the variable speed blower to run at a lower speed to get more dehumidification without excessive cooling.

3) When running in heat mode and the heat pump output is insufficient to keep up the desired temperature and the heat strips kick in, does the display indicate that the heat strips are on? does the heat pump continue to run even if it is too cold out?

 

[fabriziojoe]

Hi WayneW,
I can answer the first question about the relays.
I have 3 RC 2000s and can hear the relays click from the other room.
Not sure if this is normal, but everything has been working fine for 2+ years now.

 

[WayneW]

only one person here using the Omnistat2 that cares to comment about how loud it is or isn't? I thought lots of people used these 'stats?

 

[thill]

only one person here using the Omnistat2 that cares to comment about how loud it is or isn't? I thought lots of people used these 'stats?

I've used the HAI stats for several years in my home and in customer jobs. Yes you can definitely hear those relays when they kick in. Most people get used to it quickly and I've never really had a complaint.

 

[lupinglade]

1) Yes, they are quite clicky -- but I wouldn't complain either. Its not awful. As the previous poster said, eventually you just don't notice them as your mind blanks them out. Maybe you can place it somewhere where you won't hear it as much?


2) It will signal the blower to run at a lower speed provided its configured that way and wired correctly.

3) Not sure about this one as I don't have a heat pump. But it does indicate stage 1 with > one arrow and stage 2 with >> two arrows -- I'd imagine stage 3 or emergency heat will have >>> three arrows or some other indicator.

 

[GotHAI]

Yes there is a click. I like it as it tells me that it turned on. For example a manual change. When you accept the change, it clicks.

If this is an issue, remember that you can mount these in a remote closet and use remote sensors.

I particularly like having them out as the proximity light is an impressive feature that starts up a conversation on automation.

 

[hoang de]

I'm just reading between M1 and Omnipro2 right now.
How do you wire 2 or more T-stats to a single HVAC unit? All control lines (R, Rc, Y, W, G...) are wired in parallel?
The if one room calls for heat, the other calls for cool, how does the HAI or ELK react? First comes first serves or heat first then cool later?
Also can I use CAT5 for HAI PSEM or I have to use shielded wire? The reason I ask because I have all CAT5 cable to rooms already. I know ELK only uses simple 3 conductor cable.
Bear with me, I'm a complete newbie.
Thanks

 

[Desert_AIP]

I'm just reading between M1 and Omnipro2 right now.
How do you wire 2 or more T-stats to a single HVAC unit? All control lines (R, Rc, Y, W, G...) are wired in parallel?
The if one room calls for heat, the other calls for cool, how does the HAI or ELK react? First comes first serves or heat first then cool later?
Also can I use CAT5 for HAI PSEM or I have to use shielded wire? The reason I ask because I have all CAT5 cable to rooms already. I know ELK only uses simple 3 conductor cable.
Bear with me, I'm a complete newbie.
Thanks

My T-stats are wired to a separate zone controller (3 zones).
The Omni talks to the T-Stats over the Omni 4-wire bus to tell them what I want to happen based on time and temp.
The T-stats talk to the zone controller over the thermostat wiring which in turn talks to the HVAC system via a single thermostat wire for heat/cooling calls and the zone dampers to open and close the zones calling for heat/cooling.

 

[hoang de]

Thank you, Desert_AIP.
I have 2 HVAC units, one per each floor.
The second floor I have 4 bedrooms. Each bedroom I have two 6" round supply ducts, one with motorized damper, the other just regular register. I want when one room calls for heat or cool, all other rooms that don't need it, then their dampers would be closed.
Same to the first floor, but the lay out is little different. I have two main rectangular supply ducts, both have its own motorized damper. Each main duct has many indivisual round supply ducts to each room or big open areas that have motorized damper, too. I can use zone controller like you suggest, but each zone controller costs close to a grand (ouch!) or I just use dumb T_stat relays to HA inputs then close all dampers that don't need heat or cool. I can use a smart T_stat to control HVAC instead of zone controller.
Sorry, I'm a cheapy. I don't know anybody that uses the HA that way :mellow:

 

[Desert_AIP]

There are several threads around here about trying to use a HA controller to open and close the dampers.
You might try a sarch on zoned HVAC or something similar.
You will use up a LOT of the programming space getting this to work, especially in a complicated system like the one you describe.
From those threads, I gathered the consensus was it is far better to use a dedicated zone controller.

Hopefully some of the HVAC guys will be along.

I believe you run a real risk of short cycling the compressor, etc., if you try to run multiple T-stats in parallel on the same HAVC unit without a "traffic cop" to monitor the system as a whole.

You could open and close the dampers fairly easily, based on temperature setpoints in each room, and with little negative effect.
But if you are hooking up multiple T-stats, in multiple locations all sending demands to a single HVAC unit, that is wehn you will likely run into trouble.