HVAC questions


Senior Member
I am starting this thread on behalf of ph0n33z who is not feeling well.

He needs some advice on HVAC installation so that is is capable of being automated. I believe he is going to have 3 zones. I think he will have 3 separate air handlers instead of dampers, but not sure. How is this typically setup - 3 separate t-stats or all controlled from 1? If it will be automated is it better to have HVAC guys install system normally, then swap with RCS or similar later, or is there something specific that should be done at install time to prepare for the retrofit? Is there a specific list of components that would be needed, or just t-stats to accomplish the zoning?
My vote is to have the HVAC guys do the installation, then go back and swap thermostats. Either that, or jsut give the HVAc people your stats, and let them do the hook up.
My HVAC system is 3 zones - using dampers (it was existing when I moved in). It works quite well. I have 3 TStats - one for each zone.

Personally, I would let the HVAC guys install their own system and add your TStats later (they look just like regular thermostats). If you go with 3 zones on dampers, they will likely install a 3 zone controller to manage them. Just make sure they leave some slack wire for you when they install their thermostats - and they have 4 wires. You should be good to go then.

In my signature is a link to my setup. Scroll down to see my HVAC setup to maybe give you some ideas. Nothing fancy but it works :D
I would definitely let the HVAC guy at least pull the wire for the tstat's. The next guy that lives there may not care for the automation and it best to have the wires at least in the walls.

And three zones would get three tstat's.
Pull CAT5 from the Thermostat if Aprilaire or HAI to the HA Controller or from the RCS control box which is separate from the Thermostat Head if RCS.
I think he will have 3 separate air handlers instead of dampers, but not sure. How is this typically setup - 3 separate t-stats or all controlled from 1?
either way you get 3 tstats . . . (you need to know the temp in each zone)

If it will be automated is it better to have HVAC guys install system normally, then swap with RCS or similar later,
let the HVAC guys do the work, it will be easy to go back standard tstats if you have to . . .

or is there something specific that should be done at install time to prepare for the retrofit?
depends on what tstats you plan on using . . . if your not sure I would run cat5 from each tstat to your control point and from the HVAC zone controller to your control point . . .

Pete C

I love my country, but fear my government.
Hey guys. Firstly, I just want to thankyou so much Stevey for doing this thread for me. I am really lucky to have a friend like you. :D

About the HVAC:

My only concern was regarding the dampers for zone control. If they do not install them now, how am I going to do it down the road? Would it not be better for them to install them with the rest of the equipment?

Also, here is the setup for HVAC:

We are having 3 separate units.
1 is for the upstairs. I want to have 2 zones for this unit. One for the left side of the house(theater and game room) and one for the right side(library and guest bedroom).

The second is for the first story left wing. I would like this to have 2 zones as well. 1 for my bedroom and subsequent bathroom/laundry room. 1 for the masterbedroom, master bath, and subsequent hallway.

The final unit is for the right wing. I am not sure where the dividing line for this is, but I assume it is for the kitchen, family room, dining room, and living room. This can be 1 zone, as it is very open.

So what issues do I need to address for this? Do they need to install dampers for each zone? I know that each zone will need a thermostat, but what about the zone controller? Can it handle 3 separate units with 5 zones in total? How does it hook up to the units themselves? Can it be located in "the batcave" (the HA equipment room)

Thanks again guys!
(disclaimer - I'm not an expert (or even close)... just an enthusiast with opinions)

There are several multizone controllers available that should be able to handle your desired scenario. I would definitely let the HVAC company put in the full system - leaving out the automation capability (they install everything using basic thermostats to the zone controller).

Once they are done, you can go in and replace the basic thermostats with your smart ones and automate your HVAC system (by controlling mode (heat/fan, etc) and setpoints). Of course, to fully automate your HVAC system - you will need a smart controller (Elk, HVPro, Stargate, etc)
Bfisher: What about the dampers? Do they not need to be the ones that are controlled electronically?
my dampers (are old... but I believe the new ones are still similar) are controlled with simple 2 (or 3 or 4, can't remember) wires. The zone controller sends a signal when they need to open or close. These wires are connected directly to a motor - there are no smarts in the damper - just in the zone controller.

I believe new dampers are NO (normally open) so if the zone controller or wiring fails - they are spring loaded and will open. Mine do not do this - they will stay in whichever state they are in when they fail. It has not been an issue to date.
Sounds to me like ph0n33z wants to know if he should install the electronically controlled dampers, since he is in the middle of construction now. Normally, this is when you would do it, but since you already have a multizone system, do you still want to split those zones up as well?
Personally, I would have the HVAC company do everything you could want them to do NOW. Much easier now than later. The only thing I wouldn't have them do is add your automation thermostats - that's an easy end user job.
When you are zoning your HVAC system, you need to have a bypass installed as well. So, make sure your HVAC installer knows what you plan to do.
first a bfisher type disclaimer... Im not an expert in HVAC.. but B)

you already got a bunch of the info, but just to complete/clarify...

If you are going to have 3 units, you need 3 zone controllers. Each zone controller controls 1 HVAC unit. You can have multiple zones for each HVAC unit, and the zone controller will take care of opening and closing dampers for each zone.

You can have one or multiple dampers for each zone depending on how they set up your ducting. If there are multiple dampers per zone you will wire nut them together into a single damper output on the zone controller board.

you do want a bypass duct for each unit, but if you only have 2 or 3 zones for each unit, you shouldn't need a dump zone (usually needed for 4 or more zones).

Tstats typically require 2 cables running to them. They need a standard tstat control wire (usually 4 or 5 conducter) and a automation cable (2 or 3 conducter serial type). A tsat hooks up to the zone controller just like it was hooking up to a HVAC unit with all 4 or 5 wires. Then the serial cable is used by the automation system to "control" the tstat.

There are other types of zone control systems, but this is one of the safest in terms of future proof, and installation easy.

This way you can have the HVAC guys hook up the system, including zone controllers, with their manual tstats (or you can give them the ones you are planning on using) and make sure the system is fully functional before you take over "automation control" of the system. It will help eliminate who is at fault if something goes wrong :(

If you go this route, just make sure there is a serial cable (cat5, 18/3) from each tstat to your automation controller location. this can be in the same place as the zone controllers, but it is not necessary.


Thanks so muchh for the info guys. I did not see that you replied as I have been sick for a while.

I am going to talk with the HVAC guys today. Hoping to find out how they are ducting/wiring the house.

Another question:

Do the tstats normally wire back to the AC/HP unit? As in the big 2-3-4 ton unit that sits outside? Or is there some sort of HVAC controller(not talking about a separete ZONE controller)?

Does this make any sense?