Rheem Gra Series Installation Instructions Manual page 38

LP CONVERSION
NOTE: See Page 38 for Canadian
High-Altitude Derate
IMPORTANT: LP gas from trucks
used to transport liquid-based
fertilizers can contain chemicals that
will damage the furnace. Verify that
your gas supplier does not use the
same trucks to transport materials
other than LP.
The valve can be converted to use
liquified petroleum (LP) gas by
replacing the pressure regulator
spring with the conversion kit spring.
This LP kit spring allows the regulator
to maintain the proper manifold
pressure for LP gas.
NOTE: Order the correct LP
conversion kit from the furnace
manufacturer. Furnace conversion to
LP gas must be performed by a
qualified installer, service agency or
the gas supplier.
ORIFICE INSTALLATION
LP Gas is a manufactured gas that
has consistent heating value across
most regions.
The NFGC guidelines are used with
the following exception:
The recommended LP Gas high
altitude orifice selections differ slightly
in that the NFGC LP orifice chart, as
they are not accurate for Rheem
products. The National Fuel Gas
Code LP orifices are based on an 11
of water column pressure at the
orifice, which differs from Rheem
products that use 10 of water column
at the orifice. This difference requires
a deviation from the NFGC orifice
size recommendations. The Sea
Level input should still be reduced by
4% per thousand ft. and the orifice
size must be selected based on the
reduced input selection chart below.
Input (per
Altitude burner) 15000 Orifice Size
0 to 2000 ft. 15000
2000 -3000 13200
3000 -4000 12600
4000 -5000 12000
5000 -6000 11400
6000 -7000 10800
7000 -8000 10200
8000 -9000 9600
9000 -10000 9000
38
FIGURE 40
TYPICAL LP KIT CONTENTS
To change orifice spuds for either
conversion to LP or for elevation:
1. Shut off the manual main gas
valve and remove the gas
manifold.
2. Replace the orifice spuds.
3. Reassemble in reverse order.
4. Turn the gas supply back on and
check for proper operation and
manifold pressure. See Figures
41, 42 and 43.
5. Attach the notice label alerting
the next service technician that
the furnace has been converted
to LP gas.
1.15 mm
(factory)
1.15 mm
1.10 mm
#58
#59
#60
#62
#63
#64
ORIFICE ORDERING
INFORMATION
Orifice sizes are selected by adding
the 2-digit drill size required in the
orifice part number. Drill sizes
available are 39 through 64; metric
sizes available 1.10mm (-90) and
1.15mm (-91):
Orifice Part Number 62-22175-(drill
size)
Example 1:
#60 drill size orifice required
Part # 62-22175-60
Example 2:
1.15mm drill size orifice required
Part # 62-22175-91