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It won't be long until I'm ready to have my self-contained AC condenser unit installed. I will install the return air grill in the floor and the damper underneath the main trunk.

1. The manual says to install the damper forward of center of the home.
2. I will minimize the supply and return duct lines as much as possible.
3. I will keep the damper at least 3 feet from a floor register.
4. I'll not install the return air grill in a high-traffic area.

My question is this:
How far from/close to should the damper be installed from the return air grill that will be located in the floor?

Why do you need a damper? On the return duct too?

flcruising,

My AC unit got hooked up this morning. I guess it is referred to as a split system. The furnace has a blower that sends air down the trunk line. The AC unit also has a blower that sends air down the trunk line. When the AC unit is off, yet the furnace is on, the damper in the main trunk line closes by gravity so the heated air does not travel via the AC duct line and into the supply duct of the AC unit. When the AC unit is on, it forces open the damper on the main trunk open to allow cold air to travel through the trunk and out of the floor registers.

So you have 2 separate heating and air conditioning units sharing the same supply duct? It sounds like you need a automatic damper on the furnace as well to keep the a/c air from blowing out through that unit? are you asking where the damper should be placed in relation to the new a/c unit? I'd assume that you want it on the main trunk coming of each unit as close to each as possible. Are the two units next to each other?

FYI - A split system is one with the air handler & evaporator inside and the condensing unit outside. Linesets (refrigerant lines) run between the two.