Lochinvar COPPER-FIN 497 - 2067 - Manual (Page 24)

3
Gas connections
24
Combination gas valves
These units fire in multiple stages of burner input. Each stage
of burner operation has a combination gas valve(s) to cycle
the gas supply on and off and regulate gas to the burners. Each
combination valve consists of a gas regulator and two valve seats
to meet the requirements for redundant gas valves. The valve
has a gas control knob that must remain in the open position
at all times when the unit is in service. The gas control valve
has pressure taps located on the inlet and discharge sides of the
valve. Manifold pressure is adjusted using the regulator located
on the valve. A manifold gas pressure tap for each burner stick
is located on the discharge side of the valve. The manifold
pressure is preset at the factory and adjustment is not usually
required. If you must adjust regulator pressure, follow the
instructions under Gas Manifold Pressure Adjustment, page 25.
Venting of combination gas valves
The combination gas valve/regulator used on all units is
equipped with an integral vent limiting orifice per ANSI Z21.78.
The vent limiter ensures that the volume of gas emitted from
the valve in the event of a failed gas diaphragm does not exceed
the maximum safe leakage rate allowed by agency requirements.
Combination gas valve/regulators equipped with integral vent
limiters are not required to have vent or relief lines piped to
the outdoors. The termination of the vent limited opening on
the combination gas valve/regulator complies with the safety
code requirements of CSD-1, CF-190(a) as shipped from the
appliance manufacturer without the installation of additional
vent lines.
Checking gas supply pressure
Use the following procedure to check gas supply pressure.
1. Turn the main power switch to the “OFF” position.
2. Turn gas valve knobs to the “OFF” position.
3. Shut off gas supply at the field-installed manual gas cock in
the gas piping to the unit. If fuel supply is L.P. gas, shut off
gas supply at the tank.
4. Remove the 1/8'' hex plug, located on the “inlet” side of the
gas valve (FIG. 3-3). You may also use a tapping on the
field-installed main manual gas cock or gas piping. Install a
fitting in the inlet pressure tapping suitable to connect to a
manometer or magnehelic gauge. Range of scale should be
14'' w.c. or greater to check inlet pressure.
5. Turn on gas supply at the manual gas cock, turn on L.P. gas
at the tank if required.
6. Turn the power switch to the “ON” position.
7. Turn the gas valve knobs to the “ON” position. Set the
electronic temperature control or thermostat to call for
heat.
8. Observe the gas supply pressure as all burners are firing.
Ensure that inlet pressure is within the specified range.
See Connecting To Gas Supply, page 22 for minimum and
maximum gas supply pressures.
9. If gas pressure is out of range, contact gas utility, gas
supplier, qualified installer or service agency to determine
necessary steps to provide proper gas pressure to the
control.
TABLE 3D
GAS PIPING SIZE CHART
Nominal
Iron Pipe
Size
Inches
Length of Pipe in Straight Feet
Maximum
Capacity of Pipe
in Thousands of
Btu/hr per hour
for gas pressures
of 14 Inches
Water Column
(0.5 PSIG) or less
and a pressure
drop of 0.5 Inch
Water Column
(Based on NAT
GAS, 1025 Btu/hr
per Cubic Foot
of Gas and 0.60
Specific Gravity)
10 20 30 40 50 60 70 80 90 100 125 150 175 200
3/4 369 256 205 174 155 141 128 121 113 106 95 86 79 74
1 697 477 384 328 292 267 246 256 210 200 179 164 149 138
1 1/4 1,400 974 789 677 595 543 502 472 441 410 369 333 308 287
1 1/2 2,150 1,500 1,210 1,020 923 830 769 707 666 636 564 513 472 441
2 4,100 2,820 2,260 1,950 1,720 1,560 1,440 1,330 1,250 1,180 1,100 974 871 820
2 1/2 6,460 4,460 3,610 3,100 2,720 2,460 2,310 2,100 2,000 1,900 1,700 1,540 1,400 1,300
3 11,200 7,900 6,400 5,400 4,870 4,410 4,000 3,800 3,540 3,300 3,000 2,720 2,500 2,340
4 23,500 16,100 13,100 11,100 10,000 9,000 8,300 7,690 7,380 6,870 6,150 5,640 5,130 4,720
Installation & Service Manual