Install Instructions
TRUEZONE ARD, EARD, AND ZD SERIES DAMPERS
3 33-00040—03
Installing the Round (ARD and 
EARD) Dampers
1. Insert the crimped end of the ARD or EARD into the 
uncrimped end of the rigid round duct and secure 
with sheet metal screws (not provided). When using 
flexible duct, slip the duct over the end of the ARD or 
EARD and secure it with duct straps (not provided).
2. When installing the damper in a horizontal 
application, make sure the motor actuator is located 
on the side or top of the damper. Do not locate the 
motor on the bottom of the damper. The damper can 
be mounted in a vertical duct.
3. Adjust Range stop position to desired closed 
positions. ARD and ZD Dampers are completely 
closed in position 0. EARD Dampers are completely 
open in position 0.
Fig. 2. TrueZONE Actuator range stop positions.
Wiring Multiple Dampers
When the same zone controls two or more dampers, wire 
the dampers in parallel to terminals M1 and M6 on the 
zone control panel.
INSTALLATION OF ZD 
DAMPER
When Installing this Product…
1. Read these instructions carefully. Failure to follow 
these instructions can damage the product or cause 
a hazardous condition.
2. Check the ratings given in the instructions and on 
the product to make sure the product is suitable for 
your application.
3. Installer must be a trained, experienced service 
technician.
4. All wiring must comply with local electrical codes, 
ordinances, and regulations.
5. After completing installation, use these instructions 
to check out the product operation.
Planning the Installation
Selecting a Location
Select a location for the zone dampers that is at least three 
feet from the HVAC unit plenum in the air duct takeoff to 
the respective zone and is easily accessible for checkout 
and maintenance.
The ZD comes complete and ready for installation. The 
motor and linkage are factory-assembled to the damper. 
The damper is assembled for installation and wiring to the 
control panel.
Selecting Damper Size
To ensure correct operation, be sure to select the correct 
zone damper size for the air duct:
IMPORTANT
Be aware that ZD damper sizes are built 5/32 in. 
smaller than the listed dimensional sizes.
• If the damper is forced into an undersized air duct, the 
excess pressure can jam the damper blades and cause 
improper operation.
• When a small percentage of continuous flow is desired 
in a zone, even when the damper blades are closed, 
adjust motor closed position to be slightly open to 
maintain desired air flow.
Selecting Location with Humidifier 
Installed
IMPORTANT
Excessive lime or mineral deposits can 
accumulate on damper blades and cause 
improper operation when spray or atomizing type 
humidifiers are installed in the furnace plenum or 
air supply duct with the zone dampers.
• Spray or atomizer type humidifiers that are installed in 
the furnace plenum or air supply duct are not 
recommended.
• Evaporative type humidifiers are recommended.
Installing the Damper
IMPORTANT
— Install dampers into a squared air duct.
— Do not weld dampers to the air ducts.
— Do not force dampers into undersized air ducts.
Excess pressure can damage damper blades.
— Be sure high limit setting is less than 200 °F 
(93 °C).
— Higher settings can damage the electric actuator.
1. Be sure the ZD is correctly sized to the air duct (see 
Selecting Damper Size section).
2. Select a ZD location that is three feet from the 
furnace plenum.
3. Cut a 4-in. (102 mm) opening in the accessible side 
of the air duct at the location selected; ensure the 
opening of the air duct is cut fully from seam to 
seam.
4. Secure the ZD mounting plate to the air duct with the 
self-tapping sheet metal screws provided.
M35187A
RANGE STOP
LOCATIONS








