Existing home HVAC zoning options

[rwalker]

So I am interesting in upgrading my dual unit HVAC (1 unit up, 1 down) to a fully zoned system. There are several areas where running a new line from the HVAC units to where the thermostats need to be is impractical/impossible. I have done some research looking at options and below is what I have come up with...

Insteon enabled thermostat with a 24v DC converter (in the wall, need to figure out how to mount it..). An ISY-99i or other Insteon controller that supports the thermostats and a Insteon I/O controller with 24v DC power to open/close the dampers.

I don't like this solution for 2 reasons. I would really like something with a dedicated HVAC controller (especially one that could add humidification controls to). I looked at the Honeywell FocusPro, but that is not really what I want. I want something that mounts to the wall like a normal thermostat (120v AC) and either over powerline or wireless communicates to a hard-wired thermostat or to the zone controller. It still needs to offer some kind of automation interface so that I can tie it in with everything else.

Anyone got some better options?

Thanks,
Roy

 

[IndyMike]

I would not trust the operation of dampers to any automation technology. The system you have described does not have access to the furnace plenum temperatures and other information that is critical to the life of the system. A closed damper, at the wrong time, can easily freeze up the A-coil in the furnace and trash your Heat Pump/AC unit.

Instead of trying to automate everything, have a look at the zone control panels. These accept thermostat "requests", and drive dampers/activate the HVAC if monitored sensors indicate that it's safe to do so. You can interface wired and wireless thermostats these panels.

If you are adding zones to an existing system, you will likely need an bypass damper to prevent the airflow from dropping too low. In general, retrofitting an existing system to a zoned configuration is not exactly easy, nor is it optimal. If your system has a variable speed fan, it will help (with the correct panel controlling it).

Have a look at the following for starters: Honeywell Zone Design

 

[nexus99]

My understanding of zoned AC is that to an automation system it just looks like a bunch of different HVAC systems. HA has no idea that you are on a zoned system.

For example: You have a 4 zone HVAC system. You have 4 thermostats that tie back to a master control panel that controls the actual AC/Heat/dampers. You just set temps in each room and the master control panel handles everythign inthe background.

If you replace these thermostats with Omnistat2s to the HAI panel (for example) it just looks like 4 AC systems.

Do I have the facts straight here? I want to retrofit to 4 zones in the future (I have a simple furnace + AC system)and I think this is the way to go. A HVAC specalist that understands how to designe a zoned system is key.

 

[IndyMike]

Hi Nexus,

The system you outlined is traditional:
1) Dedicated zone control panel at the equipment - controls dampers, blower, heat/cool, humidity.
2) Remote thermostats (wired, wireless, and/or communicating) - request heat/cool/humidity for their respective zone.

The rest depends on whether you are trying to get better comfort or efficiency by zoning your system. Since you're retrofitting, it's far more difficult to gain efficiency. The equipment and ducting has already been sized for the entire home. Dividing things into smaller zones will likely mean that you'll need a bypass damper to maintain the proper airflow. Additionally, small zones may cause the equipment to cycle more often for shorter periods. This will again lower the efficiency of the equipment (it's less efficient during heat up/cool down).