29
Fig. 41 — Minimum and Maximum Airflow Adjustments, 37HS Controller
To set maximum cfm with zero minimum cfm:
1. Set diffuser or wall thermostat for maximum cooling.
2. Turn the minimum cfm star wheel counterclockwise
until the internal stop is reached. Do not attempt to over-
ride stop. (Minimum cfm has been set at zero, and the
unit will turn off when required.)
3. Adjust maximum cfm lever to desired percent cfm.
Minimum Airflow (Cfm) Adjustment
Some applications require both a design maximum cfm and a
minimum cfm. The 37HS controller can be set to provide
both airflow requirements.
To set maximum and minimum cfm:
1. Set diffuser or wall thermostat for maximum cooling.
2. Turn the minimum cfm star wheel counterclockwise
until the internal stop is reached. Do not attempt to over-
ride stop.
3. Shut off unit by adjusting thermostat to zero cooling, or
disconnect tube from volume controller to thermostat.
4. Place a standard airflow hood against the outlet of the
master unit and slowly turn the minimum cfm star wheel
on the controller clockwise until the desired minimum
cfm is reached.
5. Return the thermostat to the desired setting and/or recon-
nect tube between volume controller and thermostat.
6. Adjust maximum cfm lever to desired percent cfm.
FUNCTIONAL CHECKOUT
With building temperature within Moduline
®
thermostat set
point limits (70°F to 80°F), VAV supply air at design tem-
perature, and VAV supply pressure between 0.75 and 3.0
in. wg, check each control circuit:
1. Verify that air volume controllers are set at specified
design value.
2. Move thermostat lever to extreme right (red - warm)
position. Then check that bellows of control (master)
unit and all slave units in circuit close to negligible air-
flow.
Failure of unit(s) to close may be due to:
a. leakage or obstruction in control circuit.
b. low duct pressure in control unit.
3. Move thermostat lever to extreme left (blue-cold) posi-
tion. Verify that all bellows in the circuit open to approx-
imately the same airflow. (See Table 4.)
Different airflows may be due to:
a. faulty duct arrangement.
b. control circuit obstruction.
4. Set thermostat lever at desired setting. See Table 7 and
Fig. 42.
*With unit delivering 50
°F to 60°F supply air.
NOTE: Only slight movement of lever is necessary to change
temperature setting several degrees.
5. Refer to Tables 8 and 9 for normal cfm/duct pressure
relationships.
CFM
100
120
80
40
%
HK08ZZ030
MAXIMUM CFM LEVER
VOLUME CONTROLLER
S
O
OPEN
MINIMUM CFM
STAR WHEEL
S
O
CFM
120
100
80
40
%
Table 7 — Lever Position
LEVER POSITION
TEMPERATURE
Left (blue - cold)
65°F (approx)*
Right (red - warm)
85°F (approx)*
Centered
75°F (approx)*