Check 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
Building Pressure Control —
a variable frequency drive is controlled according to input from a pressure sensing device.
Turn both knobs to the upper most pressure setting. You may have to remove the outdoor pressure tap tubing. VAV systems should go to maximum speed. Set both knobs at the lowest setting and the VAV systems should go to minimum speed.
BLOWER
EXHAUST (OPTIONAL)
SUPPLY
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| MAIN VALVES |
HEAT |
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| DIRTY FILTERS |
75 | 70 |
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80 | 65 | (OPTIONAL) |
85 | 60 | |
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90 | 55 |
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PHOTOHELIC
GREENHECK
With Maxitrol 44 Room Thermostat
Building
Pressure Control
during installation and
Reset the correct pressure limits before starting the unit.
or in the unit.
Variable Volume Operation
The variable volume option is recommended when a building’s exhaust volume may vary. This option enables the
This picture depicts a typical photohelic setting. Typical settings are 0.0 inch wc for the lower pressure setting and 0.10 inch wc for the upper pressure setting. The needle indicates a negative building pressure. During correct operation, the indicating needle will remain between or near the setting needles.
Pressure Indicating | Pressure Setting |
Needle | Needles |
Pressure Setting Knobs
Photohelic Gauge
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
BLOWER
speed selector (potentiometer). | EXHAUST |
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SUPPLY |
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This unit allows easy manual |
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| MAIN VALVES | |
| HEAT |
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adjustment of |
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volumes. To test potentiometer |
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| DIRTY FILTERS |
operation, turn the potentiometer |
| 75 | 70 |
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80 |
| 65 | (OPTIONAL) | |
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| 60 | ||
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to the two extremes. 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.
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
22 | Model MSX | ® |