Greenheck Fan 470658 MSX manual Check Operation VAV Units optional, Variable Volume Operation

55

90

GREENHECK

Potentiometer

Control

85

Check Operation - VAV Units (optional)

NOTE

Blower Start-Up, Steps 1-5 should be performed before the blower is run.

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

		MAIN VALVES
HEAT
		DIRTY FILTERS
75	70
80	65	(OPTIONAL)
85	60
90	55

PHOTOHELIC

GREENHECK

With Maxitrol 44 Room Thermostat

Building

Pressure Control

during installation and start-up. For kitchen applications, the drive may be located in the kitchen

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 make-up air volume to track with the exhaust volume, providing only the amount of make- up air required. Control strategies include 2-speed and modulating blowers. Before the unit is left in service, the variable volume control system should be tested.

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
			(OPTIONAL)
	SUPPLY
This unit allows easy manual
				MAIN VALVES
		HEAT
adjustment of make-up air
volumes. To test potentiometer				DIRTY FILTERS
operation, turn the potentiometer		75	70
	80		65	(OPTIONAL)
			60

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 2-10 VDC or 4-20 mA signal (by others).

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 make-up air volumes based on varying cooking loads.

22 Model MSX Make-Up Air ®