284809-YIM-B-0707
16
Unitary Products Group
L.P. UNITS, TANKS AND PIPING
All gas heat units are shipped from the factory
equipped for natural gas use only. The unit may be
converted in the field for use with L.P./propane gas
with accessory kit model number 1NP0418.
All L.P./propane gas equipment must conform to the
safety standards of the National Fire Protection Associ-
ation.
For satisfactory operation, L.P./propane gas pressure
must be 10.0 I.W.C. at the unit manifold under full load.
Maintaining proper gas pressure depends on three
main factors:
1. The vaporization rate depends on (a) the tempera-
ture of the liquid and (b) the "wetted surface" area
of the container or containers.
2. The proper pressure regulation. (Two-stage regula-
tion 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 appli-
ances.
Complete information regarding tank sizing for vapor-
ization, recommended regulator settings, and pipe siz-
ing 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 com-
pleted, using a soap solution.
NEVER USE A FLAME
.
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. For units with factory installed
VFD option, the hoods and accompanying hardware
are shipped inside the gas heat section. 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 inside of the access panel opening with
four fasteners and the screws used for mounting the
hood to the panel. The top flange of this hood slips in
under the top of the access panel opening when install-
ing. Refer to Vent and Combustion Air Hood Figure 8.
FIGURE 6 - EXTERNAL SUPPLY CONNECTION
EXTERNAL SHUT-OFF
FIGURE 7 - BOTTOM SUPPLY CONNECTION
EXTERNAL SHUT-OFF
FIRE OR EXPLOSION HAZARD
FAILURE TO FOLLOW THE SAFETY WARN-
ING EXACTLY COULD RESULT IN SERIOUS
INJURY, DEATH OR PROPERTY DAMAGE.
NEVER TEST FOR GAS LEAKS WITH AN
OPEN FLAME. USE A COMMERICALLY
AVAILABLE SOAP SOLUTION MADE SPE-
CIFICALLY FOR THE DETECTION OF
LEAKS TO CHECK ALL CONNECTIONS. A
FIRE OR EXPLOSION MAY RESULT CAUS-
ING PROPERTY DAMAGE, PERSONAL
INJURY OR LOSS OF LIFE.
