![](/images/new-backgrounds/1010201/1020137x1.webp)
Operation - VAV Units (optional)
NOTE
Blower
NOTE
For maintenance issues associated with variable frequency drives, consult the drive’s manual supplied with the unit. The drives are programmed at the factory and should not need any adjustment during installation and
Variable Volume Operation
The variable volume option is recommended when a building’s exhaust volume may vary. This option enables the
2-Speed
A variable frequency drive (VFD) is used to control air volumes. The VFD can be switched to low or high speed from a remote control panel. Turn the fan speed switch on the remote control panel to each position and confirm that the fan speed adjusts accordingly.
Modulating
Potentiometer Control — a variable frequency drive is controlled by input from a remote
speed selector (potentiometer). This | EXHAUST |
(OPTIONAL) | |
unit allows easy manual adjustment | SUPPLY |
MAIN VALVES | |
HEAT | |
of |
|
BLOWER
Building Pressure Control — | SUPPLY | BLOWER | ||
a variable frequency drive is |
| |||
| EXHAUST |
| ||
controlled according to input from |
| (OPTIONAL) | ||
|
| MAIN VALVES | ||
| HEAT |
|
| |
a pressure sensing device. |
|
|
| |
Turn both knobs to the upper | 75 70 |
| DIRTY FILTERS | |
most pressure setting. You may | 80 | 65 | (OPTIONAL) | |
| 85 | 60 | ||
| 90 | 55 |
| |
have to remove the outdoor |
|
|
| |
pressure tap tubing. VAV systems |
|
| PHOTOHELIC | |
should go to maximum speed. Set |
|
|
| |
both knobs at the lowest setting |
|
| GREENHECK | |
and the VAV systems should go to | With Maxitrol 44 Room Thermostat | |||
| ||||
minimum speed. | Building | |||
Pressure Control | ||||
| ||||
Reset the correct pressure limits |
|
|
| |
before starting the unit. |
|
|
| |
Pressure Indicating |
| Pressure Setting | ||
This picture depicts a typical | Needle |
| Needles | |
|
| |||
photohelic setting. Typical |
|
|
| |
settings are 0.0 in. wg for |
|
|
| |
the lower pressure setting |
|
|
| |
and 0.10 in. wg for the upper |
|
|
| |
pressure setting. The needle |
|
|
| |
indicates a negative building |
|
|
| |
pressure. During correct |
|
|
| |
operation, the indicating |
|
|
| |
needle will remain between or | Pressure Setting Knobs | |||
near the setting needles. | Photohelic Gauge |
External Signal — a variable frequency drive is controlled according to input from an external
A 2 VDC or 4 mA signal will send the blower to low speed. The blower will go to maximum speed with a 10 VDC or 20 mA signal.
Variable Kitchen Control — A variable frequency drive is controlled by input from a remote speed control. This unit allows automatic adjustment of
Burner Bypass Damper (optional)
The
potentiometer operation, turn the |
|
| DIRTY FILTERS |
potentiometer to the two extremes. |
|
| |
75 | 70 |
| |
65 | (OPTIONAL) | ||
80 | 60 |
With variable volume, make sure the fan goes to maximum and minimum speed.
When the potentiometer is at 0, the fan speed will be at its minimum. When the potentiometer is at 100, the fan will be at its maximum speed.
used in variable volume units. Its function is to maintain proper combustion by providing a constant airflow over the burner when outside air volumes are changed. It is located underneath the burner as shown in the picture.
Burner
Bypass Damper
Burner Bypass Damper
warning
The burner bypass damper is
Model VSU
®