Form #: SIDOM.4 Page | 14 Revised: 03/19
Reverse Acting Thermostat; Normally Closed Damper (Control Sequence 1103)
1. Maximum Volume Setting:
Disconnect the thermostat line from the velocity controller.
Adjust the maximum volume control knob (marked “HI” and located in the center of
the controller) to achieve the required minimum flow. To determine the required
pressure differential, refer to Table 1, Table 2, and the Krueger Inlet Airflow Sensor
Chart that is provided on the side of the VAV unit and in Figure 6 (pg. 11).
Reconnect the thermostat line.
2. Minimum Volume Setting:
Disconnect the thermostat line from the velocity controller.
Apply 15 + psi to the thermostat port on the volume controller (marked “T”) by
tapping into the main air pressure line.
Adjust the minimum volume control knob (marked “LO” and located at the side of
the controller) until the desired pressure differential is registered on the manometer.
To determine the required pressure differential, refer to Table 1, Table 2, and the
Krueger Inlet Airflow Sensor Chart that is provided on the side of the VAV unit and
in Figure 6 (pg. 11).
Reconnect the thermostat line.
Balancing Procedure (Control Sequences 1104-1110)
1. Damper action is factory set at N.O. (normally open), or N.C. (normally closed). To change
this setting perform the following steps:
Loosen the damper selection screw.
Turn the selection dial clockwise until the “NC” or “NO” arrow aligns with the
“DAMPER” arrow.
NOTE: Accuracy in the alignment of the arrows is very important. Make this adjustment as
precise as possible. (See Figure 8 below)
2. Pipe the controller: Connect port “B” to the damper actuator. Connect port “M” to the clean,
dry main air. Connect port “T” to the thermostat output. Connect port “H” to the total pressure
tap on the airflow sensor. Connect port “L” to the static pressure tap on the airflow sensor.
The controller can be set up for cooling or heating applications using either a D.A (Direct
Acting) or R.A. (Reverse Acting) thermostat signal. The two flow adjustments are labeled
“LO STAT ∆P” and “HI STAT ∆P”.
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