COMBUSTION DISCHARGE
The products of combustion are discharged horizontally
through two screened (hooded) openings on the upper gas
heat access panel.
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” Z223.1 (in U.S.A.) or the current Gas
Installation Codes CAN/CGA-B149.1 and .2 (in Canada) should
be followed in all cases unless superseded by local codes or gas
utility requirements. Refer to the Pipe Sizing table.
The heating value of the gas may differ with locality. The value
should be checked with the local gas utility.
NOTE: There may be a local gas utility requirement specifying
a minimum diameter for gas piping. All units require a
one-inch pipe connection at the entrance fitting.
GAS CONNECTION
The gas supply line can be routed through the knockouts located on
the front of the unit or through the opening provided in the unit’s base.
Refer to the Dimensions and Clearances figure to locate these access
openings. Typical supply piping arrangements are shown in the
figures on this page. All shaded items are field-supplied.
If gas supply line is routed through the unit’s base ensure that
the burner assembly can be removed for maintenance without
disturbing the supply line. The supply piping and fittings must
lie below the bottom gas manifold to avoid interference with the
burner assembly.
Two grommets are shipped in the blower compartment (in parts
bag taped to the blower housing) of every unit with gas heat
and should be used in the knockouts when the gas piping
penetrates the front of the unit.
After the gas supply piping has been installed, the bottom
opening in the unit should be sealed to prevent water from
leaking into the building.
Gas piping recommendations:
1. A drip leg and a ground joint union must be installed in the
gas piping.
2. When required by local codes, a manual shut-off valve may
have to be installed outside of the unit.
3. Use wrought iron or steel pipe for all gas lines. Pipe
compound should be applied sparingly to male threads
only.
WARNING: Natural gas may contain some propane. Propane,
being an excellent solvent, will quickly dissolve
wh it e l ea d o r mo st st andard commer cial
compounds. Therefore, a special pipe compound
must be applied when wrought iron or steel pipe is
used. Shellac base compounds such as Gaskolac
or Stalastic, and compounds such as Rectorseal
#5, Cyde’s or John Crane may be used.
4. All piping should be cleaned of dirt and scale by hammering
on the outside of the pipe and blowing out the loose dirt and
scale. Before initial start-up, be sure that all of the gas lines
external to the unit have been purged of air.
5. The gas supply should be a separate line and installed in
accordance with all safety codes as prescribed under
“Limitations”. After the gas connections have been
completed, open the main shut-off valve admitting normal
gas pressure to the mains. Check all joints for leaks with
soap solution or other material suitable for the purpose.
NEVER USE A FLAME.
6. The furnace and its individual manual shut-off valve must
be disconnected from the gas supply piping system during
any pressure testing of that system at test pressures in
excess of 1/2 psig (3.48kPa).
The furnace must be isolated from the gas supply piping
system by closing its individual manual shut-off valve during
any pressure testing of the gas supply piping system at test
pressures equal to or less than 1/2 psig (3.48kPa).
7. A 1/8 inch NPT plugged tapping, accessible for test gage
connection, must be installed immediately upstream of the
gas supply connection to the furnace.
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.
Input Capacity (Mbh)
Output Capacity (Mbh)
Available
on Models
Gas
Rate
2
(Ft.
3
/Hr.)
Temp.
Rise
°
F
At
Full Input
3
0 To
2,000 Feet
Above
Sea Level
2,000 To
4,500 Feet
Above
Sea Level
1
0 To
2,000 Feet
Above
Sea Level
2,000 To
4,500 Feet
Above
Sea Level
1
Max.
Min.
Max.
Min.
Max.
Max.
Min.
Max.
300
150
270
135
240
213
15 & 20 Ton
279
20
50
400
200
360
180
320
281
15 & 20 Ton
372
30
60
NOTE: Heaters are shipped available for natural gas, but can be converted to
L.P. / Propane with Kit Model No. 1NP0418.
1
MBH rating should be reduced at the rate of 4 percent for each 1,000 feet above 4,500 feet.
2
Based on maximum input and 1075 Btu/Ft
3
.
3
The air flow must be adjusted to obtain a temperature rise within the range shown.
TABLE 3 - GAS HEAT APPLICATION DATA
Length in Feet
Nominal Iron Pipe Size
1 in.
1-1/4 in.
10
20
30
40
50
60
70
80
90
100
520
350
285
245
215
195
180
170
160
150
1,050
730
590
500
440
400
370
350
320
305
Maximum capacity of pipe in cubic feet of gas per hour. (Based upon a pressure drop of 0.3
inch water column and 0.6 specific gravity gas).
TABLE 4 - PIPE SIZING
FIG. 6 - EXTERNAL SUPPLY CONNECTION
EXTERNAL SHUT-OFF
FIG. 7 - BOTTOM SUPPLY CONNECTION
EXTERNAL SHUT-OFF
530.18-N6Y
6
Unitary Products Group