1061903-XIM-A-0713
20 Johnson Controls Unitary Products
Optional Gas Heat
These gas-fired heaters have aluminized-steel or optional
stainless steel, tubular heat exchangers with spark ignition with
proven pilot.
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 CSA-B149.1 (in Canada) should be
followed in all cases unless superseded by local codes or gas
utility requirements. Refer to the Pipe Sizing Table 13. 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.
Figure 16: External Supply Connection External Shut-Off
Figure 17: Bottom Supply Connection External Shut-Off
NOTE: Maximum capacity of pipe in cubic feet of gas per hour
based upon a pressure drop of 0.3 inch W.C. and 0.6
specific gravity gas.
Table 13: Gas Application Data
Unit
Input
(MBH)
Output (MBH)
Temp Rise
(°F)
Size Opt.
180
24 300 240 20-50
32 400 320 30-60
240
24 300 240 20-50
32 400 320 30-60
Drip Leg
Main
Manual
Shut-off
Valve
Table 14: Gas Pipe Sizing - Capacity of Pipe
Length of
Pipe ft. (m)
Nominal Iron Pipe Size
1 in. 1-1/4 in.
10 (3)
520 (14.7) 1050 (29.7)
20 (6)
350 (9.9) 730 (20.6)
30 (9.1)
285 (8) 590 (16.7)
40 (12.1)
245 (6.9) 500 (14.1)
50 (15.2)
215 (6) 440 (12.4)
60 (18.2)
195 (5.5) 400 (12.4)
70 (21.3)
180 (5) 370 (10.4)
80 (24.3)
170 (4.8) 350 (9.9)
90 (27.4)
160 (4.5) 320 (9)
100 (30.4)
150 (4.2) 305 (8.6)
Table 15: Gas Heat Minimum Supply Air Imperial
Size
(Tons)
Heat Size
Supply Air (CFM)
Cooling Heating
Min Max Min Max
180
(15)
24 4500 7000 4500 7000
32 4500 7000 4500 7000
240
(20)
24 6000 9400 6000 9400
32 6000 9400 6000 9400
Table 16: Gas Heat Minimum Supply Air Metric
Size
(Tons)
Heat Size
Supply Air (M
3
/S)
Cooling Heating
Min Max Min Max
180
(15)
24 2.13 3.3 2.13 3.3
32 2.13 3.3 2.13 3.3
240
(20)
24 2.83 4.44 2.83 4.44
32 2.83 4.44 2.83 4.44
Drip Leg
Main
Manual
Shut-off
Valve
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