Figure 48
Pipe capacity for natural gas
Gas
pipe
total
length
(feet)
Gas supply pipe capacity (cubic feet per
hour)
@ 0.30” w.c. pressure drop
EWDKEHGGVRGTJQWTURGEKſEITCXKV[
2”
2½”
3”
4”
10
3050
4800
8500
17500
20
2100
3300
5900
12000
30
1650
2700
4700
9700
40
1450
2300
4100
8300
50
1270
2000
3600
7400
70
1050
1700
3000
6200
100
870
1400
2500
5100
150
710
1130
2000
4100
Figure 49
Equivalent lengths of straight pipe for gas
line fittings
0IPESIZE
inches
%QUIVALENTLENGTHFEET
90° Elbow
Tee
2”
5.17
10.3
2½”
6.16
12.3
3”
7.67
15.3
4”
10.1
20.2
Gas piping
(continued)
SVF
™
Series 1
Commercial Condensing Gas-Fired Water Boiler
— Boiler Manual
Part number 550-100-250/0819
48
Pipe sizing for Natural Gas
1. Size gas supply piping from meter outlet to entrance of boiler in ac-
cordance with Figure 48 and Figure 49.
2. Use the total input of all connected appliances. Divide the total input in
Btuh by 1,000 to obtain approximate cubic feet per hour of natural gas.
a. Pipe lengths in Figure 48 are equivalent lengths of straight pipe. Use
Figure 49 to determine equivalent length of fittings.
b. Figure 48 is only for natural gas with specific gravity 0.60, with a
pressure drop through the gas piping of 0.30” w.c.
c. For additional gas pipe sizing information, refer to ANSI Z223.1/
NFPA 54 - latest edition (or Natural Gas and Propane Installation
Code - CAN/CSA B149.1 for Canadian installations).
Pipe sizing for propane gas
Contact gas supplier to size pipes, tanks and 100% lockup gas pressure
regulator. Gas pipe must be properly sized with a 100% lockup gas pressure
regulator in the gas supply line. An undersized gas pipe feeding the boiler(s)
can cause problems.
Multiple boiler applications —manifolded
gas supply lines
1. Size gas supply piping as instructed above.
2. At each boiler, provide a manual shutoff gas valve, union and sediment
trap (minimum 3 inches below tee) as shown in Figure 46, page 47.
3. Ensure the piping is large enough so that the minimum pressure at
each boiler, with all connected appliances firing, will be as specified
on page 47.
Gas pressure switches
1.
SVF
TM
boilers are equipped with manual reset high gas pressure and
low gas pressure switches (see Figure 47, page 47).
2. These switches are factory set and should remain at the following set-
tings:
a. High gas pressure: 14 inches w.c.
b. Low gas pressure: 2 inches w.c.
The low gas pressure switch must be manually reset (button
on front of switch) on initial startup or any time the gas supply
is turned off.
Gas Train Diagram
+
0
81,21
3
%2,/(5
&211(&7,21
3
6$0(
9$/9(%2'<
/
3
3
6
6
5
3
0
),(/'3,3,1*±*$6
7$%/(
6 6$)(7<6+87±2))9$/9(
5 =(52*29(51255(*8/$725
0 0$18$/6+87±2))9$/9(
/ /2:*$635(6685(6:,7&+
+ +,*+*$635(6685(6:,7&+
3 35(6685(7$3
#2
#3
#1
From Figure 47, page 47.
