ADJUSTMENT OF MANIFOLD GAS PRESSURE
Be sure to relight any gas appliances that were turned off at the start of this input check.
Table 11: Inlet Gas Pressure Range
INLET GAS PRESSURE RANGE
| Natural Gas | Propane (LP) |
Minimum* | 4.5” W.C. (1.12 kPa) | 8.0” W.C. (1.99 kPa) |
Maximum | 10.5” W.C. (2.61 kPa) | 13.0” (3.24 kPa) W.C. |
*The gas line pressure MUST BE
•7” W.C. (1.74 kPA) for Natural Gas
•11” W.C. (2.74 kPA) for Propane (LP) Gas
in order to obtain the BTU input specified on the rating plate and/or the nominal manifold pressure specified in these instructions and on the rating plate.
The inlet gas pressure operating range table specifies what the minimum and maximum gas line pressures must be for the furnace to operate safely.
Follow the appropriate section in the instructions below. Refer to Figure 29, "Gas Valve" for a drawing of the locations of the pressure ports on the gas valve.
Turn gas off at the ball valve or gas cock on gas supply line before the gas valve.
1.The manifold pressure must be taken at the port marked OUT PRESS TAP.
2.The inlet gas line pressure must be taken at the port marked IN PRESS TAP.
3.Using a 3/16” allen wrench, remove the plugs from the inlet and outlet pressure ports. Connect a 1/8” UPT barbed hose fitting to each pressure port.
The cap for the pressure regulator must be removed entirely to gain access to the adjustment screw. Loosening or tightening the cap does not adjust the flow of gas.
4.Refer to Figure 29, "Gas Valve" for location of pressure regulator adjustment cap and adjustment screws on main gas valve.
5.Turn gas and electrical supplies on and follow the operating instructions to place the unit back in operation.
6.Adjust manifold pressure by adjusting gas valve regulator screw for the appropriate gas per the following:
TABLE 12: Nominal Manifold Pressure
NOMINAL MANIFOLD PRESSURE
Natural Gas (Max) | 3.5" w.c. (0.87 kPa) |
Natural Gas (Min) | 0.9" w.c. (0.22 kPa) |
Propane (LP) Gas (Max) | 10.0" w.c. (2.49 kPa) |
Propane (LP) Gas (Min) | 2.5" w.c. (0.62 kPa) |
On/Off |
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| Regulator | |||
Knob |
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| Adjustment | |||
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Inlet |
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| Outlet |
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Pressure |
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| Pressure | |
Tap |
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| Tap | |
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FIGURE 29: Gas Valve
If gas valve regulator is turned in (clockwise), manifold pressure is increased. If screw is turned out (counterclockwise), manifold pres- sure will decrease.
7.After the manifold pressure has been adjusted,
8.Once the correct BTU (kW) input has been established, turn the gas valve to OFF and turn the electrical supply switch to OFF; then remove the flexible tubing and fittings from the gas valve pressure tap and the pressure reference hose from the burner box and replace the pressure tap plugs. Replace the burner box front cover (if it was removed) and place the pressure reference hose back on the gas valve.
9.Turn the electrical and gas supplies back on, and with the burners in operation, check for gas leakage around the gas valve pressure port for leakage using an approved gas detector, a
ADJUSTMENT OF TEMPERATURE RISE
The temperature rise, or temperature difference between the return air and the supply (heated) air from the furnace, must be within the range shown on the furnace rating plate and within the application limitations shown in Table 6, "Ratings & Physical / Electrical Data"
The supply air temperature cannot exceed the “Maximum Supply Air Temperature” specified in these instructions and on the fur- nace rating plate. Under NO circumstances can the furnace be allowed to operate above the Maximum Supply Air Temperature. Operating the furnace above the Maximum Supply Air Temperature will cause premature heat exchanger failure, high levels of Carbon Monoxide, a fire hazard, personal injury, property damage, and/or death.
After about 5 minutes of operation, determine the furnace temperature rise. Take temperature readings of both the return air and the heated air in the ducts about six feet away from the furnace, where they will not be affected by radiant heat. Increase or decrease the temperature rise by changing the ATR jumper on the furnace control board. The jumper is
Do not move the motor wires to different positions on the furnace control board!
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