Weil-McLain 2 Series Manual page 46

®
SlimFit Series 2
Gas piping
Pipe sizing
1. Size gas supply piping from meter outlet to entrance
of boiler in accordance with Figure 49 and Figure 50.
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 49 are equivalent lengths of
straight pipe. Use Figure 50 to determine equivalent
length of fittings.
b. Figure 49 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/NFPA54 -latest edition (or Natural
Gas and Propane Installation Code - CAN/CSA
B149.1 for Canadian installations).
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 47, page 45.
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 45.
Gas pressure switches
1. SlimFit boilers are equipped with manual reset high gas
pressure and low gas pressure switches (see Figure 48,
page 45).
2. These switches are factory set and should remain at the
following settings:
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
46
COMMERCIAL CONDENSING GAS
(continued)
-
FIRED WATER BOILER
Pipe capacity for natural gas
Gas pipe
total
(cubic feet per hour, 0.60 specific gravity)
length
10 1600 3050
20 1100 2100
30 890 1650
40 760 1450
50 670 1270
70 560 1050
100 460 870
150 380 710
Equivalent lengths of straight pipe for gas line fittings
inches
1½
2
2½
3
4
— Boiler Manual
4800 8500
3300 5900
2700 4700
2300 4100
2000 3600
1700 3000
1400 2500
1130 2000
Tee
4.02 8.04
5.17 10.3
6.16 12.3
7.67 15.3
10.1 20.2
Part number 550-100-180/0917
17500
12000
9700
8300
7400
6200
5100
4100