FUNCTIONAL CHECKOUT — With building temperature
within Moduline® thermostat set point limits (70 to 80 F),
VAV supply air at design temperature and VAV supply pres-
sure between 0.75 and 3.0 in. wg, check each control circuit:
1. Verify that air volume controllers are set at specified de-
sign value.
2. Move thermostat lever to extreme right (red - warm) po-
sition. Then check that bellows of control (master) unit
and all slave units in circuit close to negligible airflow.
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 approxi-
mately 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 Fig. 40.
LEVER
POSITION
TEMPERATURE
SETTING
Left (blue - cold) 65 F (approx)*
Right (red - warm) 85 F (approx)*
Centered 75 F (approx)*
*With unit delivering 50 to 60 F supply air.
NOTE: Only slight movement of lever is necessary to change
temperature setting several degrees.
5. Refer to Table 7 for normal cfm/duct pressure relation-
ships.
Table 7 — Minimum Static Pressure at Control
(Master) Unit — Units with System-Powered
Controls and Standard Diffusers
AIRFLOW
(Cfm)
37HS1 37HS2 37HS4
PLENUM SIZE (in.)
7x7 7x7 9x9
5x7 9x9 9x9 11x11
11x11 11x11 13x13
Minimum Static Pressure (in. wg)
40
0.75 0.75 — —
50
60
70
80
0.75 0.75 0.75 —90
100
110 0.90 0.90 0.75 —
120
— — 0.75 —
140
160
— — 0.75 0.75180
200
220 — — 0.90 0.75
240
— — — 0.75
280
320
360
400
440 — — — 0.90
NOTE: Maximum inlet pressure — 3.0 in. wg.
MINIMUM AIRFLOW (cfm)
37HS1 37HS2 37HS4
40 80 160
START-UP
Principles of Operation
GENERAL — Units are normally open (bellows deflated).
Rise in bellows pressure closes unit. When thermostat is call-
ing for no flow, pressure differences between unit plenum
(measured at control filter) and bellows should be less than
0.1 in. wg.
A leakmay cause bellows in circuit to be fully open, par-
tially open or fully closed depending on location of the leak.
An obstructionprevents operation of all bellows down-
stream. The inoperative bellows may remain open or closed,
depending on whether air has been trapped in them.
CONSTANTVOLUME OPERATION — Both high and low
pressure control air from the plenum of the master unit passes
through the filter to the volume controller.An adjustable bleed
orifice reacting to the relative change of high and low pres-
sure allows a set amount of control air to press-
urize the bellows until unit air delivery matches the control-
ler setting.
THERMOSTAT
LEVER
IN CDILING
Fig. 40 — Thermostat Lever Detail
28
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