Gas Manifold Pressure Adjustment - Lochinvar 399 Installation And Service Manual

Check burner performance by cycling the system while you
observe burner response. Burners should ignite promptly.
Flame pattern should be stable, see
Turn system off and allow burners to cool, then cycle burners
again to ensure proper ignition and flame characteristics.
FIG. 30 Measuring Gas Supply Pressure at Combination
Gas Valve
Nominal Iron
Pipe Size,
(Inches) 10
"
3/4 369
1" 697
"
1 1/4 1,400
"
1 1/2 2,150
2" 4,100
2-1/2" 6,460
3" 11,200
4" 23,500 16,100
Maximum capacity of pipe in thousands of BTU's per hour for gas pressures of 14 Inches Water Column (0.5 PSIG) or less and a total system
pressure drop of 0.5 Inch Water Column (Based on NAT GAS, 1025 BTU's per Cubic Foot of Gas and 0.60 Specific Gravity).
, page 56.
Multiple Unit Installations Gas Supply Pipe Sizing
Length of Pipe In Straight Feet
20 30 40
256 205 174
477 384 328
974 789 677
1,500 1,210 1,020
2,820 2,260 1,950 1,720
4,460 3,610 3,100 2,720
7,900 6,400 5,400 4,870
13,100 11,100 10,000
Installation and
Service Manual

Gas Manifold Pressure Adjustment

IMPORTANT:
referenced
chamber by a hose connected from the
vent of the gas valve regulator to the
chamber pressure tap located on the front
inside portion of the jacket. Reference the
drawings in this section for component
and connection points for pressure
measurement.
connecting a manometer or magnehelic
must be followed to obtain actual net
manifold pressure for normal operation. A
manometer or magnehelic gauge legible
in 0.1" increments up to 10 inches w.c. is
required to check and adjust the manifold
pressure. The regulator cover screw on
the gas valve must be in place and tight at
all times for the unit to operate properly.
1. Loosen knurled knob that fastens the control panel access
door and pull out control panel.
2. Turn the power switch located in the lower left corner
behind the control panel access door to the "O" or "OFF"
position.
3. Remove the top front jacket access panels to access the gas
valves.
TABLE - L
50 60 70 80
155 141 128 121
292 267 246 256
595 543 502 472
923 830 769 707
1,560 1,440 1,330
2,460 2,310 2,100 2,000 1,900
4,410 4,000 3,800 3,540 3,300
9,000 8,300 7,690 7,380 6,870
31
The gas valves
to the fan pressurized
The procedure
90 100 125 150
113 106 95 86
210 200 179 164
441 410 369 333
666 636 564 513
1,250 1,180 1,100 974
1,700 1,540 1,400 1,300
3,000 2,720 2,500 2,340
6,150 5,640 5,130 4,720
are
for
175 200
79 74
149 138
308 287
472 441
871 820