Lennox International Inc 15GCSX Post Start−up Check List Gas, Checking and Adjusting Gas Input

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To Shut Down:

1 − Turn off electric power to unit.

2 − Turn the gas valve knob to the OFF position.

Post Start−up Check List (Gas)

After the control circuit has been energized and the heating section is operating, make the following checks:

1 − Use soap solution to check for gas leaks in the unit piping as well as the supply piping.

2 − Check for correct manifold gas pressures. See

3 − Check the supply gas pressure. It must be within the limits shown on rating nameplate. Supply pressure should be checked with all gas appliances in the building at full fire. At no time should the supply gas pressure exceed 10.5 inches w.c., nor drop below 5.0 inches w.c. for natural gas units. For propane gas, supply gas pressure should not drop below 11 inches w.c. If gas pressure is outside these limits, contact your gas supplier for corrective action.

4 − Adjust temperature rise to the range specified on the rating plate.

Checking and Adjusting Gas Input

NOTE − Units must be converted for use with LP/propane gas. Conversion kit is ordered separately. Conversion must be performed by an approved licensed pipe fitter or technician.

The minimum permissible gas supply pressure is 5.0 inches W.C. for natural gas or 11.0 inches W.C. for LP/propane gas. The maximum inlet gas supply pressure is 10.5 inches W.C. for natural gas and 13.0 inches W.C. for LP/propane gas. Gas input must never exceed the input capacity shown on the rating plate.

Units fueled by natural gas are rated for manifold pressures of 2.0 inches W.C. for first stage and 3.5 inches W.C. for second stage.

Units fueled by LP/propane gas are rated for manifold pressures of 5.6 inches W.C. for first stage and 10.0 inches W.C. for second stage.

Measure manifold pressure: Shut off gas supply to the unit. Remove plug from pressure tap. See figure 13. Connect manometer or gauge to the proper pressure tap, then turn on the gas supply.

The Honeywell VR8205 gas valve has separate adjusting screws for first stage (LO) and second stage (HI). The adjusting screws are positioned on either side of the barbed fitting. Turn the adjusting screws clockwise to increase pressure and input; turn counterclockwise to decrease pressure and input. The pressure regulator adjustment is sensitive. One turn of the adjusting screw results in a large change in manifold pressure.

Final first−stage and second−stage manifold pressures must be within the allowable rangers for the gas being used.

For Natural Gas: Check the furnace rate by observing gas meter, making sure all other gas appliances are turned off. The test hand on the meter should be timed for at least one revolution. Note the number of seconds for one revolution.

BTU/HR =

Cubic Feet Per Revolution

X 3600 X Heating Value

 

 

 

INPUT

No. Seconds Per Revolution

 

The heating value of your gas can be obtained from your local utility.

For LP/Propane Gas: If a gas meter is available, check the input rate as described in the section above. Heating value of propane gas is available from propane supplier. Otherwise, the only check for the output rate is to properly adjust the manifold pressure using a manometer. Typical manifold setpoint for installations at altitudes from 0 to 4500 feet above sea level is 10.0 inches W.C.

High Altitude Information

Ratings shown on the rating plate for elevations up to 4,500 feet. For elevations above 4,500 feet, ratings should be reduced at a rate of four percent for each 1,000 feet above sea level. See National Fuel Gas Code Z223.1 (latest edition) or the requirements of the CSA B149 installation codes.

Heating Sequence of Operation

When the thermostat calls for heating, W1 is energized. NOTE − The ignition control ignores a call for second−stage heat until first−stage heat has been established.

The ignition control checks high temperature limit and roll out switches to make sure they are closed. The control then verifies that the pressure switch is open. If the pressure switch is closed, the control will flash code 3 on the LED and will wait indefinitely for the pressure switch to open. If the pressure switch is open, the control proceeds to the 15−second pre−purge.

The ignition control energizes the combustion air inducer on high speed, flashes a code 3 on the LED, and waits for the pressure switch to close.

When the pressure switch has closed, the LED code 3 flash stops and the control begins the 15−second pre−purge period. When the pre−purge time has expired, the control begins the ignition trial.

The ignition control energizes the gas valve and spark. The control ignores the flame sense signal for the first two seconds of the ignition trial. If the flame is established within 10 seconds, the control de−energizes the spark. If flame is not established within 10 seconds, the gas valve and spark are de−energized and the ignition control initiates a 30−second inter−purge sequence.

Approximately 30 seconds after the flame has been established, the circulating air blower starts and the combustion air inducer is switched to low speed. The ignition control inputs are continuously monitored to ensure that limit switch(es), roll out switch and pressure switch are all closed, and that the flame remains established and heating demand is present. First−stage gas valve, low−speed combustion air inducer and

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Contents Table of Contents Retain These Instructions For Future Reference15GCSX Unit Dimensions − inches mm LbsSafety Information General Parts ArrangementShipping & Packing List Location Selection Service Clearances − Inches Millimeters Rigging & Setting UnitAccessory Lift Kit ClearancesVent Hood Installation Vent Hood InstallationExisting Common Vent Systems Page Condensate Drain FiltersTypical Condensate Drain Removing Supply and Return Supply & Return Duct ConnectionsUnit Filter Size Air Opening CoversGas Supply and Piping Gas Piping and Electrical Conduit AccessCompressors Gas Heat Application DataIsolate Gas Valve To Pressure Test Drip Leg InstallationPressure Test Gas Piping Gas piping recommendationsElectrical 208/230 Line Voltage WiringHeat Anticipator Setting Thermostat15GCSX Series Gas Packaged Units Typical Wiring Diagram Blower Control A54 Blower Control A54Cool Cooling Start−Up Heating Start−Up Normal Operating PressuresHoneywell VR8205 Series Gas Valve High Altitude Information Checking and Adjusting Gas InputPost Start−up Check List Gas Heating Sequence of OperationBlower Control A54 Blower Delay − HeatingUnit Controls Ignition Control A3Ignition Control Pressure SwitchRollout Switch Ignition Control LED CodesSystem Operation Monitor Lsom Comfort Alert Code Auto−Reset FunctionCondenser Fan Clearances System Operation Monitor A132System Operation Monitor LED Troubleshooting Codes Maintenance Planned ServiceRepair Parts & Accessories
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Gas Packaged Units, 15GCSX specifications

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