ZONE-AIR
BYPASS DAMPER
INSTALLATION INSTRUCTIONS
DESCRIPTION
This bypass damper was designed for use with zoned warm air heating and air conditioning systems. It is installed in a connecting duct between the furnace ple- num or the supply duct and the cold air return duct.
Its purpose is to control and compensate for excess volume and velocity of the air due to the closing of the dampers leading to some of the zones.
The bypass damper, operating by means of air pressure, permits any excess volume of air to pass directly to the cold air return, avoiding an increased air velocity through the remaining open ducts which would result in discomfort to the occupants of that zone.
INSTALLATION
All parts needed for the bypass damper are provided except the damper vane. The vane should be cut from a piece of sheet metal to the proper size to fit the duct.
The bypass duct should be properly sized. It should be designed to handle at least the same amount of air as the supply duct, less that required by the smallest zone.
If several zones are not calling for heat, the bypass damper should be partially open; if only one zone is calling for heat, the bypass damper should be open.
NOTE
The damper located in the bypass duct has a counter- weighted arm. It operates through the pressure of the air as opposed to the torque of the weighted arm. Adjust the counterweight so that with all zones calling for heat, the fan in operation, and all ducts open, the bypass damper is in the closed position.
See the layout for zoned warm air system on page 2 for additional information.
Connecting
Duct
Furnace
Plenum
Counter-
weighted Arm
Partially open; one
or more zones closed; fan operating
Air pressure |
| |
bypass damper | Cold Air | |
closed; all zones | ||
Return | ||
open and/or | ||
Open position; | ||
not operating | ||
most zones closed; | ||
| fan operating |
6