Page 40
4.13 Natural Gas to Propane Conversion (continued)
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www.Laars.com
Document 4290C
The FT Series, Floor-Standing, Gas Conversion Kit
pg 3 of 4
Manifold pressure
Gas Type ‘NG’
Gas Type ‘LP’
2" VENT
3" VENT
2" VENT
3" VENT
FTCF140
MAX Fire
-0.15
"
WC
-0.216
"
WC
-0.15
"
WC
-0.216
"
WC
MIN Fire
0
”
WC
0.002
”
WC
0.1
”
WC
0.079
”
WC
FTCF199
MAX Fire
-0.134
”
WC
-0.173
”
WC
MIN Fire
-0.015
”
WC
-0.015
”
WC
Figure D
15.
Setup your combustion Analyzer and
place the sensor into the combustion test port.
16.
Per
Table B for Max Fire
,
change dip switch 6 to ON and 7 to OFF.
The unit will cycle up to MAX fi re.
17.
WAIT for your combustion Analyzer to stabilize. This may take up to 3 minutes depending on your combustion
Analyzer. Then check the CO
2
measurement for MAX fi re. Refer to Table D for acceptable MAX fi re
combustion readings. At this point, just record the CO
2
readings at MAX Fire.
Do NOT attempt to adjust
CO2 at MAX Fire. ONLY in MIN Fire, so...
18.
Per
Table B for MIN Fire
,
change dip switch 6 to OFF and 7 to ON. The unit will cycle down to MIN Fire.
19.
WAIT for your combustion Analyzer to stabilize. Then check the CO
2
measurement at MIN fi re. Refer to
Table D for acceptable MIN fi re combustion readings.
20.
If CO2
readings in Max Fire and MIN fi re are acceptable, then skip ahead to Step 23. If not, then open the
Gas Valve Adjustment Port by removing the cap screw with a 4mm Allen wrench. See Figure E.
21.
Then use the 4 mm Allen wrench to make a minor adjustment (1/8 turn) to either increase or decrease CO
2
.
Table B
DIP Switch Settings
Photo shows a model
140 using 3" venting
and natural gas.
MBH 140 199
ON
OFF
MIN
Fire
Normal Operation
MAX
Fire
Normal Operation
NG Natural
LP Propane
3” Vent Size
2” Vent Size
ON
OFF
ON
ON
ON
OFF
OFF
ON
OFF
ON
ON
ON
REFE
RENCE
ON
LY.
CO
2
value
Gas Type ‘NG’
Gas Type ‘LP’
2" VENT
3" VENT
2" VENT
3" VENT
FTCF140
MAX Fire
8.5~10.5%
9.5~11 %
MIN Fire
8~10%
9~10.5 %
FTCF199
MAX Fire
8.5~10.0%
9.5~11 %
MIN Fire
8~10%
9~10.5 %
Table C
Table D
