Greenheck VSU-112 User Manual
Vertical Direct Gas-Fired Make-Up Air
Model VSU
• 800 – 60,000 cfm • up to 7,000,000 Btu/hr
November
2007
Product Features
Model VSU
Vertical Direct Gas-Fired
Make-Up Air Unit
The Greenheck model VSU provides a 100% efficient
direct gas-fired heating and ventilating unit in a
vertical configuration. This configuration removes
the equipment weight load from the roof and offers
an easier means of installation. Ground level filters,
dampers, and controls also simplify servicing.
The VSU is specifically designed for providing heating
and make-up air for manufacturing facilities and
warehouses. Airflow volumes up to 60,000 cfm and
heating capacities up to 7,000,000 Btu/hr. are offered.
Durable Construction
Designed for maximum weather resistance, VSU
Housings are constructed of heavy gauge G90
galvanized steel. Lifting lugs are standard.
Direct Gas-Fired System
• Cast aluminum burners with
stainless steel mixing plates
• Maxitrol burner modulation
control
• Flame safeguard with digital
fault indicator capability
• 25:1 turn down ratio
Control Center
The control center includes the
following standard components:
• Magnetic motor starter
with solid state overload
protection
• Control transformer with
fusing
• Integral door interlocking
disconnect switch
• Separately fused motor
• Distribution terminal strip
Premium grade control components are selected
for reliable operation. All electrical components are
UL Listed, recognized or classified and factory prewired
for single point power connection.
Vibration Isolators
The entire fan and motor
assembly is mounted on
vibration isolators to minimize
noise transmission into the
building.
2
Access Doors and Panels
Large access doors and panels are provided for
easy inspection and maintenance of motors, drives,
fan wheels, filters, and heater controls.
Centrifugal Blowers
Double width, double inlet forward curved wheels
for high efficiency and low sound levels are
constructed of heavy gauge steel. Wheels are
balanced to ensure vibration free operation.
Factory Wired and Tested
All units are
tested prior to
shipment. Units
are checked
for vibration
and proper
operation.
Application
100% Make-Up Air
The 100% Make-Up Air system is recommended when outdoor air is required to replenish a constant volume
of exhaust air. This system provides efficient heating of the make-up air and minimizes unwanted infiltration.
Some of the most popular applications include paint booths, warehouses, kitchens and factories. Benefits of
this system include low operating cost, low initial cost, simplicity and reliability. See page 5 for a wide range of
factory supplied accessories.
Variable Volume System
The variable volume option is recommended when a
building’s exhaust volumes are variable. This option
enables the make-up air volume to track with the
exhaust volume, providing only the amount of
make-up air that is required.
The variable volume VSU saves energy in two ways.
First, the fan power is reduced whenever make-up
air requirements are less than the maximum. Second,
whenever lower air volumes are sufficient, the VSU
requires less gas to heat the outdoor air.
Airflow Control Strategies
Greenheck offers four methods of controlling the
make-up air volume. All four vary the fan speed for
maximum energy savings.
• Variable Frequency Drive controlled by building
pressure.
• Variable Frequency Drive controlled manually with
a remote potentiometer.
• Variable Frequency Drive controlled by a 2-10 VDC
or 4-20 mA signal.
• 2 speed motor controlled manually with a remote
switch.
Burner By-Pass
Damper
The variable volume
option includes a
patented burner
by-pass damper,
which maintains
the pressure drop
across the burner as
air volumes change.
This assures that
complete and proper
combustion occurs.
The by-pass damper
is self-adjusting,
designed for minimal
maintenance, and
requires no controls.
Discharge
Arrangements
For installation flexibility, fan
discharges are available in either
Horizontal or Upblast Discharge.
Horizontal Discharge
Upblast Discharge
3
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