Install Instructions

Table Of Contents
INSTALLATION—CONTINUED
Piping Connections—Continued
Gas Supply Piping—Continued
Table 14. Gas Supply Line Sizes
Length
of Pipe
(Feet)
Diameter of Pipe (Inches)
1/2 3/4 1 1-1/4 1-1/2 2
Natural
Gas
Propane
Natural
Gas
Propane
Natural
Gas
Propane
Natural
Gas
Propane
Natural
Gas
Propane
Natural
Gas
Propane
Cubic Feet per Hour
20 92 56 190 116 350 214 730 445 1100 671 2100 1281
30 73 45 152 93 285 174 590 360 890 543 1650 1007
40 63 38 130 79 245 149 500 305 760 464 1450 885
50 56 34 115 70 215 131 440 268 670 409 1270 775
60 50 31 105 64 195 119 400 244 610 372 1105 674
70 46 28 96 59 180 110 370 226 560 342 1050 641
80 43 26 90 55 170 104 350 214 530 323 990 604
90 40 24 84 51 160 98 320 195 490 299 930 567
100 38 23 79 48 150 92 305 186 460 281 870 531
125 34 21 72 44 130 79 275 168 410 250 780 476
150 31 19 64 39 120 73 250 153 380 232 710 433
175 28 17 59 36 110 67 225 137 350 214 650 397
200 26 16 55 34 100 61 210 128 320 195 610 372
20
I-UBX-UBZ-UDX-UDZ (04-21) 1034344-0
Supply Piping Connections
Install a ground joint union and manual shutoff valve upstream of the unit control system, as shown in Figure 9.
The 1/8-inch plugged tapping in the manual shutoff valve in Figure 9 provides connection for a supply line pressure
test gauge.
The National Fuel Gas Code requires the installation of a trap with a minimum 3-inch drip leg (see Figure 9). Local
codes may require a drip leg longer than 3 inches (typically 6 inches). To permit burner removal, this drip leg must
extend beyond the edge of the heater.
Leak-test all connections by brushing on a leak-detecting solution. Bleed trapped air from gas lines as needed.
The gas connection is made at the pipe nipple that extends outside the cabinet, as shown in Figure 9. Gas
connection sizes are listed in Table 15.
Figure 9. Gas Connections