Fuel Consumption; Fuel Pressure; Power Loss; Fuel Pipe Sizing - Rheem GEN12AD-V Manuel D'installation

Fuel Consumption

Estimated fuel supply requirements at half and full load for
natural gas and LP vapor fuels are shown below.
Natural Gas
1/2 Load Full Load
12 kW 119.46 C 197.00 C
119,460 B 197,000 B 127,500 B 213,300 B
C = Cubic feet per hour
B = BTU's per hour
Physical Properties
Normal Atmospheric State
Boiling Point (in °F):
Initial
End
Heating Value:
BTU per gallon (Net LHV*)
BTU per gallon (gross**)
Cubic feet (gas)
Density***
Weight†
Octane Number:
Research
Motor
* LHV (Low Heat Value) is the more realistic rating.
** Gross heat value does not consider heat lost in the form of water
during combustion.

Fuel Pressure

Both LP vapor and natural gas fuel supply pressure at the
generator's fuel inlet port should be between the following
levels at full load with all gas appliances turned on
and operating.
Ensure that all gas line shutoff valves are OPEN and that
adequate fuel pressure is available whenever automatic
operation is desired.
LP Vapor
1/2 Load Full Load
51.00 C 85.32 C
LP Vapor Natural
Gas
Gas Gas
-44 -259
-44 -259
83,340 63,310
91,547
2,500 1,000
36.39 57.75
4.24 24 24 2.65
110+ 110+ + 110+
97 97 97
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Power Loss

Air density is less at high altitudes, resulting in less available
engine power. Specifically, engine power will decrease 3.5%
for each 1,000 feet (300 meters) above sea level and 1% for
each 10° F (5.6°C) above 77°F (25°C). Make sure you and
your installer consider these factors when determining total
generator load.

Fuel Pipe Sizing

There are numerous on-line or otherwise-published
references for fuel pipe sizing. For example, NFPA 54-Natural
Fuel Gas Code, 2006 (Item #: 320-6031-06) is a
common resource.
The installer should consider the specific gravity of gas and
compensate for a nominal amount of restriction from bends,
fittings, etc. If an unusual number of fittings, bends, or other
restrictions are used, refer to federal and local codes
for guidance.

Fuel Conversion

The engine of your generator system is factory calibrated to erator syste rator syste
run on natural gas (NG). It may also be operated on liquefied NG). It may a G). It may
petroleum (LP) vapor. There is no additional hardware/ apor. There apor. There i
equipment required to switch between either fuel. However, uired to swit uired to sw
LP fuel inlet pressure must be between 11 and 14 inches t pressure m t pressure
water column at full load with all gas appliances turned on lumn at full lumn at fu
and operating. perating. perating.
To configure the fuel system for LP use: To configure To configure
1. 1. Set 1. Set generator's system switch to OFF. Set
2. Remove 15 Amp fuse from control panel. 2. 2.
3. Remove roof, divider, side panels, exhaust panel and
muffler cover.
4. Change main jet in fuel mixer following instructions
provided in LP Conversion Kit.
5. Reinstall muffler cover, exhaust panel, side panels,
divider and roof.
6. Reinstall 15 Amp fuse in control panel.
7. Set generator's system switch to AUTO.
The system is now ready to operate automatically using LP
vapor fuel.
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