Can I sectionalize my air conditioning per room?

Old 02-23-08, 06:29 AM
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Can I sectionalize my air conditioning per room?


We are moving into a house soon and it an older home with an oil burner for heat and an air conditioner with air ducts. We are planning on removing the oil in place of electric heat.

What I am wondering is, aside from simply closing air vents, can we sectionalize the air conditioner / heater on a per room basis; meaning every room would have its own thermostat?

If so, does anyone happen to have links to documentation or the like?
Old 02-23-08, 07:36 AM
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Yes you can do this. It's called a Zone Controlled System.

Basically what happens is they install a control board (circuit board) at the air handler/furnace that is wired directly to it, then they put a remote thermostat in each area you want to control and wire them back to this control board.

The ductwork going to each of the areas with the thermostat will have a Damper in it that is powered by a servo motor. The servo motors are wired back to the control board.

There is typically also an additional duct and sometimes equipment set up to dump the extra air that isn't being used from the supply side of the unit right back to the return side so the pressures stay ok.

When you, say, have a call for AC in the living room but not in the other rooms the living room Servo will open that vent but all of the others will remain closed, the unit will fire up and when the room reaches temp it will close back again.

They can also set up the dampers so that they are always partly open a little bit so you still get a tiny bit of air flow/circulation.

Here is a VERY basic picture to give you some idea:

Hope this helps,
Old 02-23-08, 08:11 AM
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What you would need and what Micheal describes is a variable air volume damper.
There is a problem using it on an existing ductwork installation however.

You would need to have this damper located at the branch to each room you want to control and then have another duct run back to the furnace for the bypass air.
Besides being a major ductwork installation you can only bypass a small percentage of the total air because the a/c and furnace needs to have a certain load to cool or heat.
Technically this can be done but I am not sure if you would be prepared for the cost.

You really only need to do this if the heating or cooling load in a particular room changes.
For a house this seldom occurs and all you really need is to have the ducts properly balanced or faults corrected.
Old 02-23-08, 08:16 AM
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Id say forget it. Any set up like that is a pain and the cost dont pay back a thing. Yes they do work on large jobs but not for a home. If it is a two story home then better to put two system in it. Have had two homes the same one with the zone control and one with two system. Fuel cost for the home with two system way way less for heat and cool. With that zone set up you have to have a bypass damper in it. So think about it you pay to heat the air and it just goes round and round in the duct. Cause only half of it can get out .When just one zone calls for heat.. You said electric heat. So if so you want a heatpump with a HSPF over 8.05.
Go to to compare fuel cost for where you live. Make sure to get 3 bids for the job.

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