Install Instructions

9
A. Size gas piping. Design system to provide adequate gas
supply to boiler. Consider these factors:
1. Allowable pressure drop from point of delivery to
boiler. Maximum allowable system pressure is ½
psig. Actual point of delivery pressure may be less;
contact gas supplier for additional information.
Minimum gas valve inlet pressure is listed on rating
label.
2. Maximum gas demand. Table 2 lists boiler input
rate. Also consider existing and expected future gas
utilization equipment (i.e. water heater, cooking
equipment).
3. Length of piping and number of ttings. Refer to
Table 3 for maximum capacity of Schedule 40 pipe.
Table 4 lists equivalent pipe length for standard
ttings.
IV. Gas Piping
Table 2: Rated Input
Boiler
Model
Number
Input Rate
[cubic feet per hour]
Gas
Connection
Size
Natural Gas LP/Propane
20 37.5 15.0 ½
30 62.0 24.8 ½
40 96.0 38.4 ½
50 130.0 52.0 ½
60 164.0 65.6 ½
70 198.0 79.2 ¾
80 232.0 92.8 ¾
90 266.0 106.4 ¾
100 299.0 119.6 ¾
Length
[Feet]
0.3 inch w.c. Pressure Drop 0.5 inch w.c. Pressure Drop
½ ¾ 1 1¼ ½ ¾ 1 1¼
10 132 278 520 1,050 175 360 680 1,400
20 92 190 350 730 120 250 465 950
30 73 152 285 590 97 200 375 770
40 63 130 245 500 82 170 320 660
50 56 115 215 440 73 151 285 580
60 50 105 195 400 66 138 260 530
70 46 96 180 370 61 125 240 490
80 43 90 170 350 57 118 220 460
90 40 84 160 320 53 110 205 430
100 38 79 150 305 50 103 195 400
Table 3: Maximum Capacity of Schedule 40 Pipe in CFH for Natural Gas Pressures of 0.5 psig or Less
4. Specic gravity of gas. Corrections for the specic
gravity of natural gas can be found in Table 5.
For materials or conditions other than those listed
above, refer to National Fuel Gas Code, NFPA
54/ANSI Z223.1, or size system using standard
engineering methods acceptable to authority having
jurisdiction.
Table 4: Fitting Equivalent Lengths
Fitting
Nominal Pipe Size
½ ¾ 1 1¼
45° Ell 0.7 1.0 1.2 1.6
90° Ell 1.6 2.1 2.6 3.5
Tee
(As Elbow)
3.1 4.1 5.2 6.9
Table 5: Specic Gravity Correction Factors for
Natural Gas
Specic
Gravity
Correction
Factor
Specic
Gravity
Correction
Factor
0.50 1.10 1.30 1.07
0.55 1.04 1.40 1.04
0.60 1.00 1.50 1.00
0.65 0.96 1.60 0.97
0.70 0.93 1.70 0.94
0.75 0.90
0.80 0.87