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VENT AIR
OUTLET
HOODS
COMBUSTION
AIR INTAKE
HOOD
FIG. 8 - VENT AND COMBUSTION AIR HOODS
All L.P./propane gas equipment must conform to the safety
standards of the National Fire Protection Association.
For satisfactory operation, L.P./propane gas pressure must be
8.8 inch W.C at the unit under full load. Maintaining proper gas
pressure depends on three main factors:
1. The vaporization rate which depends on (a) the
temperature of the liquid and (b) the "wetted surface" area
of the container or containers.
2. The proper pressure regulation. (Two-stage regulation is
recommended from the standpoint of both cost and
efficiency.)
3. The pressure drop in the lines between regulators and
between the second stage regulator and the appliance.
Pipe size required will depend on the length of the pipe run
and the total load of all appliances.
Complete information regarding tank sizing for vaporization,
recommended regulator settings, and pipe sizing is available
from most regulator manufacturers and L.P./propane gas
suppliers.
L.P./propane gas is an excellent solvent and special pipe
compound must be used when assembling piping for this gas
as it will quickly dissolve white lead or most standard
commercial compounds. Shellac base compounds such as
Rectorseal #5 are satisfactory for this type of gas.
Check all connections for leaks when piping is completed,
using a soap solution. NEVER USE A FLAME.
Unitary Products Group
VENT AND COMBUSTION AIR HOODS
Two vent hoods and a combustion air hood (with screens) are
shipped attached to the blower housing in the blower
compartment. These hoods must be installed to assure proper
unit function. All hoods must be fastened to the outside of the
gas heat access panel with the screws provided in the bag also
attached to the blower housing.
The screen for the combustion air intake hood is secured to the
SLOTTED
inside of the access panel opening with four fasteners and the
OPENINGS IN
screws used for mounting the hood to the panel. The top flange
ACCESS PANEL
of this hood slips in under the top of the access panel opening
when installing. Refer to Vent and Combustion Air Hood figure.
Each vent hood is installed by inserting the top flange of the
hood into the slotted opening in the access panel and securing
in place.
OPTIONAL ECONOMIZER/MOTORIZED DAMPER
RAIN HOOD
The instruction for the optional economizer/motorized damper
rain hood can be found in form 44-320-2. Use these instructions
when field assembling an economizer rain hood onto a unit.
The outdoor and return air dampers, the damper actuator, the
GAS HEAT
damper linkage, the outdoor and return air divider baffles, and
ACCESS
all the control sensors are factory mounted as part of the
PANELS
"Factory installed" economizer option.
ENTHALPY SET POINT ADJUSTMENT
Remove the economizer access panel from the unit to check
the following adjustments. Loosen but do not remove the two
panel latches.
CAUTION: Extreme care must be exercised in turning both the
6. The enthalpy set point may now be set by selecting the desired
setpoint shown in the Adjsuting Enthalpy Setpoint figure. Adjust
as follows:
•
For a single enthalpy operation, carefully turn the set
point adjusting screw to the "A", "B", "C" or "D" setting
corresponding to the lettered curve.
•
For a dual enthalpy operation, carefully turn the set point
adjusting screw fully clockwise past the "D" setting.
7. To check that the damper blades move smoothly without
binding, carefully turn the minimum position adjusting
screw fully clockwise and then energize and de-energize
terminals "R" to "G". With terminals "R" to "G" energized,
turn the minimum position screw counterclockwise until the
desired minimum position has been attained.
8. Replace the economizer access panel. Reposition the two
latches horizontally and retighten the screws.
POWER EXHAUST/BAROMETRIC RELIEF DAMPER
AND RAIN HOOD OPTION
The instructions for the power exhaust/barometric relief
damper and rain hood can be found in form 44-320-10. The
exhaust fan, all supporting brackets, angles, and the wiring are
factory installed as part of the power exhaust option.
All of the components, including the dampers, hardware, and
mounting instructions are shipped in a single package external
from the unit. The hood must be field assembled and installed.
Power exhaust is not available as a field installed option.
setpoint and minimum position adjusting screws to
prevent twisting them off.
530.18-N6Y
7
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