Specifications

035-17377-000 (0201) REV A
26 Unitary Products Group
GAS HEAT
LP 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 LP gas with accessory kit model number
1NP0441.
All LP gas equipment must conform to the safety standards of
the National Fire Protection Association.
For satisfactory operation, LP gas pressure must be 10.5
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 the temperature
of the liquid and the “wetted surface” area of the con-
tainer(s).
2. The proper pressure regulation. (Two-stage regulation is
recommended).
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 LP gas suppliers.
LP gas is an excellent solvent and will quickly dissolve white
lead and most standard commercial compounds. A special
pipe dope must be used when assembling wrought iron or
steel pipe for LP. Shellac base compounds such as Gaskolac
or Stalastic, and compounds such as Rectorseal #5, Clyde’s,
or John Crane may be used.
GAS PIPING
Proper sizing of gas piping depends on the cubic feet per
hour of gas flow required, specific gravity of the gas, and the
length of run. National Fuel Gas Code, ANSI Z223.1 - Latest
Edition should be followed in all cases unless superseded by
local codes or gas company requirements. Refer to Table 24.
The heating value of the gas may differ with locality. The
value should be checked with the local gas utility. In Canada
please refer to the Natural Gas and Propane Installation
Code CSA - B149.
TABLE 23: GAS HEAT LIMIT SETTINGS
*
*.
Rollout = 300°F, Auxiliary Limit = 200°F
# of HX Tubes Main Limit Setting
4
215°F
6
195°F
8
160°F
FIGURE 17 : SIDE ENTRY GAS PIPING
FIGURE 18 : BOTTOM ENTRY GAS PIPING
OPTIONAL
COIL
GUARD
SHOWN