Weil-McLain LGB-23 User Manual
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Part Number 550-141-916/1001
Part Number 550-141-916/1001
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Part Number 550-141-916/1001
LGB-6 to LGB-23
II Gas piping
1. Size gas piping considering —
a. Diameter and length of gas supply piping.
b. Number of fittings.
c. Maximum gas consumption (including any possible future expansion).
d. A llowable pr essur e dro p fr om gas meter outlet to boile r. For pr essure dr ops, see
ANSI-Z223.1 – latest edition. Canadian installations must comply with B149.1 or
B149.2 Installation Code.
2. Size natural gas piping from Table 3, belo w. Size piping to pr ovide proper inlet pressur e to
gas valve when operating at rated input.
a. Inlet gas pressure to manual main shut-off gas valve —
minimum 7" W.C. standard (5" on special order) – maximum 13" W.C.
b. If pressur e to gas valve ex ceeds 13" W.C., install positiv e dead-end lockup gas pressur e
regulator upstream of hand valve.
c. T o obtain appro ximate cubic feet per hour , di vide input (BTU/HR) by 1000.
3. Remove gas supply knockout disc from jacket panel.
4. Follow good piping practices.
5. Pipe joint compound (pipe dope) must be resistant to corrosive action of liquefied
petroleum gases. Apply sparingly only to male threads of pipe joints.
6. Install drip leg at inlet of gas connection to boiler . W here local utility requires, exte nd drip
leg to floor.
7. Install ground joint union when required for servicing.
8. Support piping by hangers, not by boiler or its accessories.
9. Purge all air from supply piping.
10 . Before operating boiler , check boiler and its gas connections for leaks.
Do not check for gas leaks with an open flame – BUBBLE TEST . Failure to
use bubble test or test for leaks can cause seve re personal injury , death or
substantial property damage.
a. Close manual main shut-off valve during any pressure testing at less than 13" W.C.
b. Disconnect boiler and gas controls from gas supply piping during any pressure test
greater than 13" W.C.
11 . Set gas pressure switch as follow s or to local inspector’ s req uirements (LGB-21 thr ough
LGB-23 only):
a. High – 14" W .C.
12 . Canada only - manual main shut-off valve must be identified by installer .
Series 2 – Control Supplement
T able 3
Natural gas supply pipe sizing
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Pipe
Size
1 ¼" 1,050 730 590 500 440 360 305 250
1 ½" 1,600 1,100 890 760 670 545 460 380
2" 3,050 2,100 1,650 1,450 1,270 1,020 870 710
2 ½" 4,800 3,300 2,700 2,300 2,000 1,650 1,400 1,130
3" 8,500 5,900 4,700 4,100 3,600 2,900 2,500 2,000
4" 17,500 12,000 9,700 8,300 7,400 6,000 5,100 4,100
*Include measured length of gas supply piping and allowance in feet for number and size of fittings.
*Pipe length, in feet (Natural Gas capacities, listed in MBH)
10 20 30 40 50 75 100 150
Part Number 550-141-916/1001
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