4
Tft285 NG-LP Conversion Instructions
Adjustments to the
Throttle/Input Adjustment Screw
may only be made by a qualified gas
technician, while using a calibrated combustion analyzer capable of measuring CO
2
and CO.
Adjustments may only be performed if the gas line pressure is maintained above minimum
levels throughout the duration of the test, see Table 2-1. Failure to follow these instructions
may result in serious injury or death.
Adjustment
Throttle / Input Screw Adjustments -
The boiler is equipped with a Throttle/Input Adjustment Screw, located on the
Gas Valve. It is used to adjust the flow of gas leaving the gas valve entering the Venturi and then the combustion
air stream. Turn the adjustment screw in (clockwise) to reduce gas flow, make combustion leaner, and reduce the
CO
2
concentration in the flue gases. To increase the CO
2
level and gas flow in the combustion air stream, adjust
the Throttle screw out (counterclockwise). Typical adjustment for LP Gas is 0-1/4 turns in or out from the factory
setting upon inserting the LP orifice as per these conversion instructions. See Figure 1-1 for throttle screw location.
Combustion Calibration
- To calibrate burner operation, perform the following procedure using a calibrated
combustion analyzer capable of measuring CO
2
and CO from Natural and Propane Gas burning boilers:
1.
Operate the unit at the maximum modulation rate, see Table 2-2.
2.
Ensure the gas line pressure is maintained within tolerance, see Table 2-1.
3.
While at the maximum modulation rate, measure the CO
2
and CO; adjust as necessary, using the Throttle
Screw, to be within the limits listed in Table 2-1.
4.
Operate the unit at the minimum modulation rate (see Table 2-2). Ensure the combustion remains smooth and
CO
2
and CO values are lower than the values obtained during maximum modulation as per notes in Table 2-1.
If not, do not adjust further, contact NTI for assistance.
Failure to perform the flue gas analysis and adjustment as detailed in this section may result in
erratic and unreliable burner operation, leading to reduced efficiency, increased fuel
consumption, reduced component life, heat exchanger combustion deposits, and general
unsafe operation. Failure to follow these instructions may result in serious injury or death.
3.0 Labeling
As the certified installer of the Natural Gas to LP Conversion Kit, you must indicate on the boiler that it has been
converted for use with Propane (LP) Gas:
1.
Update Rating Plate Decal
– Locate the rating plate decal on the side of the appliance, using a regular ink pen,
check the box next to “Field converted to Propane Gas” and fill in the date; depress hard enough to permanently
etch the decal (see Figure 3-1).
2.
Conversion Decal
- Fill out the required information on the Conversion Decal (included in this kit) and affix it to
the boiler cabinet adjacent to the rating plate decal, and in a location where it can be easily seen (see Figure 3-2).
Figure 3-1 Update the Rating Plate Decal
Figure 3-2 Conversion Decal
Throttle/Input Adjustment Screw
Increase gas
Turn Counter Clockwise
Decrease gas
Turn Clockwise
X
x
May 5, 2016
John Smith
