Greenheck Fan VSU Make-Up Air Unit with Direct-Fired Gas Heater 470654 - Manual (Page 15)

15 Model VSU Make-Up Air
®
Set-Up Optional Components
Adjust the settings on the optional components. See
the unit’s specific wiring diagram located on the access
door or the unit.
• Heating Inlet Air Sensor
Typical setting: 60-70ºF
• Building Freeze Protection
Typical setting: 5 minutes; 45ºF
• Dirty Filter Gauge
Typical setting: Settings vary greatly for each unit.
(see Reference section for adjusting information)
Check the Supply Gas Pressure
Check the supply gas pressure and compare it with
the unit’s nameplate pressure requirements. Adjust
the supply regulator as needed until the supply gas
pressure is within the specified range. The direct gas
nameplate is located on the outside of the unit on the
control center side.
Check the Pilot Gas Pressure
Check the pilot gas pressure. The recommended
gas pressure is 3 in. wg. Adjust the pilot regulator as
needed. See the Gas Train Layout in the Reference
section for the location of the pilot pressure test port
and pilot regulator.
Check the Optional High and Low Gas Pressure
Switches
Check the settings on the high and low gas pressure
switches. The high gas setting is typically 8 in. wg
(2 kPa) and the low gas setting is typically 3 in. wg
(0.7 kPa). The switches are set at the factory and should
not need adjustment. Adjust the settings if needed. See
the Gas Train Layout in the Reference section for the
high and low pressure switch location.
Start-Up - Direct Gas
IMPORTANT
For proper unit function and safety, follow the start-up
procedure in the exact order that it is presented.
IMPORTANT
This start-up should begin after all of the installation
procedures and the blower start-up have been
completed.
Direct Gas Nameplate
“ WC
“ WC
“ WC
F
PSI
“ WC
“ WC
MAX BTU/HR
BTU/H MAX
NORMAL MANIFOLD
PRESSURE
PRESSION DÕADMISSION
NORMALE
MIN GAS
PRESSURE
PRESSION DE GAZ
MIN BURNER
PRESSURE DROP
PERTE MIN DE PRESSION
DANS LE BRULEUR
TYPE OF GAS
NATURE DU GAZ
MIN BTU/HR
BTU/H MIN
MIN GAS PRESSURE
FOR MAX OUTPUT
PRESSION DE GAZ MIN
POUR PUISSANCE MAX
MAX BURNER
PRESSURE DROP
PERTE MAX DE PRESSION
DANS LE BRULEUR
MAX GAS
PRESSURE
PRESSION DE GAZ
MAX
DESIGN ΔT
ΔT NORMALE
EQUIPPED FOR
CONCU POUR
SCFM “ WC
EXTERNAL STATIC PRESSURE
PRESSION STATIQUE EXTERIEURE
AGAINST
CONTE
Minimum and maximum gas
pressures for maximum output
Type of gas
IMPORTANT
The purpose of the high and low gas pressure
switches is to automatically shut down the burner
if the inlet gas pressure is too low for the burner to
safely light, or if the manifold pressure is too high for
the burner to operate properly.