27
TABLE 7
LP GAS PIPE CAPACITY TABLE (CU. FT./HR.)
Maximum capacity of pipe in thousands of BTU per hour of undiluted liquefied petroleum gases (at 11 inches water column
inlet pressure).
(Based on a Pressure Drop of 0.5 Inch Water Column)
Nominal Length of Pipe, Feet
Iron Pipe
Size, Inches 10 20 30 40 50 60 70 80 90 100 125 150
1/2 275 189 152 129 114 103 96 89 83 78 69 63
3/4 567 393 315 267 237 217 196 182 173 162 146 132
1 1,071 732 590 504 448 409 378 346 322 307 275 252
1-1/4 2,205 1,496 1,212 1,039 913 834 771 724 677 630 567 511
1-1/2 3,307 2,299 1,858 1,559 1,417 1,275 1,181 1,086 1,023 976 866 787
2 6,221 4,331 3,465 2,992 2,646 2,394 2,205 2,047 1,921 1,811 1,606 1,496
Example (LP): Input BTU requirement of unit, 120,000
Equivalent length of pipe, 60 ft. = 3/4” IPS required.
LP CONVERSION
LP Conversion
NOTE: The valve can be converted to use liquified petro-
leum (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. See Figure 21.
NOTE: Order the correct LP conversion kit from the fur-
nace manufacturer. Furnace conversion to LP gas must
be performed by a qualified installer, service agency or the
gas supplier.
NOx MODELS
When converting furnaces equipped with NOx inserts to LP gas,
remove the NOx insert assemblies. Steps for removal are listed
below:
1. Turn off all electrical power and the gas supply to the furnace.
2. Remove the burner door from the furnace.
3. Remove the burner assembly – handle with care.
4. Remove the two screws attaching the NOx insert retainer
bracket to the center panel and remove NOx inserts.
5. Put the two screws back into the holes in the center panel.
6. Re-install the burner assembly.
7. Replace burner door.
8. Turn on electrical power and gas supply to the unit.
NOTE: Some NOx models may have one less NOx insert.
ORIFICE INSTALLATION
LP Gas is a manufactured gas that has consistent heating
value across most regions.
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 in High Alt. Instruction
Section.
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 op-
eration and manifold pressure.
5. Attach the notice label alerting the next service techni-
cian that the furnace has been converted to LP gas.
!
WARNING
LP TANKS FROM LOCAL LP SUPPLIER MUST NOT
BE USED TO STORE ANYTHING (SUCH AS FER-
TILIZER) EXCEPT LP GAS. THIS INCLUDES ALL
DELIVERY VESSELS (LP TRUCKS). IF MATERIAL
OTHER THAN LP GAS IS USED IN THE SAME VES-
SELS/TANK AS THE LP GAS, THE LP GAS CAN
BECOME CONTAMINATED AND DAMAGE THE
FURNACE. THIS WILL VOID THE MANUFACTUR-
ER’S WARRANTY. CONTACT THE SUPPLIER TO
MAKE SURE FERTILIZER IS NOT USED IN THE
SAME TANKS USED TO STORE AND DELIVER LP
GAS.
GAS PRESSURE
FIGURE 21
TYPICAL LP KIT CONTENTS
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