Johnson Controls TM9T*MP installation manual Adjustment of Manifold GAS Pressure & Input Rate

Page 31

505309-UIM-D-0511

ADJUSTMENT OF MANIFOLD GAS PRESSURE & INPUT RATE

Inlet and manifold gas pressure may be measured by connecting the “U” tube manometer to the gas valve with a piece of tubing. Follow the appropriate section in the instructions below. Refer to Figure 39 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. Find the pressure ports on the gas valve marked Out P and In P.

1.The manifold pressure must be taken at the port marked OUT P.

2.The gas line pressure must be taken at the port marked IN P.

3.Using a 3/32” (2.4 mm) Allen wrench, loosen the set screw by turn- ing it 1 turn counter clockwise. DO NOT REMOVE THE SET SCREW FROM THE PRESSURE PORT.

Read the inlet gas pressure

Connect the positive side of the manometer to the IN P Tap on the gas valve. Do not connect any tubing to the negative side of the manometer, as it will reference atmospheric pressure. Refer to Figure 40 for connec- tion details.

1.Turn gas and electrical supplies on and follow the operating instruc- tions to place the unit back in operation.

Table 16: 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” w.c. (3.24 kPa).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The inlet gas pressure operating range table specifies what the mini- mum and maximum gas line pressures must be for the furnace to operate safely. The gas line pressure MUST BE a minimum of:

•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.

2.Once the correct gas inlet pressure has been established, see Table 16, turn the gas valve to OFF and turn the electrical supply switch to OFF; then remove the flexible tubing from the gas valve pressure tap and tighten the pressure tap plug using the 3/32” (2.4 mm) Allen wrench.

3.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 non-corrosive gas leak detec- tion fluid, or other non-flammable leak detection methods.

Read the manifold gas pressure

Connect the positive side of the manometer to the adapter previously installed in the OUT P Tap on the gas valve. Do not connect any tubing to the negative side of the manometer, as it will reference atmospheric pressure. Refer to Figure 40 for connection details.

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.

NOTICE

The regulated outlet pressure has been calibrated at the factory. Additional pressure adjustment should not be necessary. If adjust- ment is necessary, set to the following specifications. After adjust- ment, check for gas leakage.

This gas valve has separate regulator adjustment screws for high fire and low fire, as shown in Figure 39. The procedure below is used to adjust either the high fire manifold pressure or the low fire manifold pressure.

1.Refer to Figure 39 for location of pressure regulator adjustment cap and adjustment screws on main gas valve.

2.Turn gas and electrical supplies on and follow the operating instruc- tions to place the unit back in operation.

3.Adjust manifold pressure by adjusting gas valve regulator screw for the appropriate gas per the following:

Table 17: Nominal Manifold Pressure

NOMINAL MANIFOLD PRESSURE

Natural Gas (High Fire)

3.5" w.c. (0.87 kPa)

 

 

Natural Gas (Low Fire)

1.6" w.c. (0.40 kPa)

 

 

Propane (LP) Gas (High Fire)

9.8" w.c. (2.488 kPa)

 

 

Propane (LP) Gas (Low Fire)

4.0" w.c. (0.99 kPa)

 

 

HIGH STAGE REGULATOR

ADJUSTMENT

 

OUTLET

 

PRESSURE

 

PORT

VENT

 

PORT

INLET

OUTLET

 

WRENCH

 

BOSS

 

INLET

 

PRESSURE

 

PORT

LOW STAGE REGULATOR

ON OFF

SWITCH

ADJUSTMENT

FIGURE 40: 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.

4.After the manifold pressure has been adjusted, re-calculate the fur- nace input to make sure you have not exceeded the specified input on the rating plate. Refer to “CALCULATING THE FURNACE INPUT (NATURAL GAS)”.

5.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 from the gas valve pressure tap and tighten the pressure tap plug using the 3/32” (2.4 mm) Allen wrench.

6.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 non-corrosive gas leak detec- tion fluid, or other non-flammable leak detection methods.

Johnson Controls Unitary Products

31

Page 30 Page 32
Image 31
Page 30 Page 32
Contents List of Tables Models TM9T*MPList of Sections List of FiguresSpecific Safety Rules and Precautions Section I SafetySafety Requirements Codes and Standards Combustion AIR Quality List of ContaminantsFurnace Location and Clearances InspectionDuct Flanges Floor Base and Ductwork Installation DownflowSection II Ductwork Ductwork General InformationCoil Flange Installation Coil InstallationCOIL/FURNACE Assembly MC/FC/PC Series Coils Furnace Assembly MC & FC Series CoilsCritical Coil Projection Coil / Furnace Assembly HC Series CoilsDownflow Duct Connectors Bottom Return and Attic InstallationsDownflow Application Attic InstallationSuspended Furnace / Crawl Space Installation Horizontal ApplicationSection III Filters Filter InstallationSide Return Horizontal Filters GAS SafetyGAS Piping Installation Section IV GAS PipingGAS Orifice Conversion for Propane LP Section V Electrical PowerHigh Altitude Pressure Switch Conversion Electrical Power ConnectionsSupply Voltage Connections LOW Voltage Control Wiring ConnectionsPP32U70124 DN22H00124 DP22U70124 Two Stage Air Conditioner Two Stage PSC FurnaceTWO Stage PSC Furnace OD Models Section VI Twinning Condensate hoses must slope downwards at all points Twinning InstructionsTwinning Operation Condensate Drain LocationTypical. Combustion Pipe Drain Tee Condensate Drain TerminationWill cause the furnace Airflow Horizontal Left Johnson Controls Right ConfigurationModel Input Pipe Size Maximum Combustion AIR and Vent SafetySection Viii Combustion AIR and Vent System Combustion AIR/VENT Pipe SizingFitting Equivalent Length Combustion AIR and Vent Piping AssemblyElbow a Dimension Combustion AIR / VentingHome Layout Vent ClearancesVent Applications and Termination Vent SystemVenting Multiple Units Ambient Combustion Air Supply Downward VentingOutdoor Combustion Air Combustion AIR SupplyFree Area Combustion Air Source From OutdoorsDampers, Louvers and Grilles Canada Only Air Supply Openings and Ducts Vent Blower Rotation Specially Engineered Installations Ventilated Combustion Air Ventilated Combustion Air TerminationIgnition System Sequence Section IX START-UP AdjustmentsGAS Piping Leak Check Calculating the Furnace Input NAT. GASSeconds For Revolution Cu FtRead the inlet gas pressure Adjustment of Manifold GAS Pressure & Input RateRead the manifold gas pressure Adjustment of FAN Control Settings Adjustment of Temperature RiseBottom Airflow Data Scfm Blower Performance CFM Any Position without filterLeft Side Airflow Data Scfm Section XI Normal Operation and Diagnostics Section X Safety ControlsFurnace Control Diagnostics Diagnostic Fault Code Storage and Retrieval Section XII Replacement Parts ListFabricated Parts Wiring Diagram Section Xiii Wiring DiagramJohnson Controls Unitary Products York Drive Norman, OK
Top Page Image Contents