Accurex XDG Installation, Operation And Maintenance Manual
                                                                | |
Contents
| 
Direct Gas Make-Up Air286. Set the Burner Air Pressure DifferentialFor units equipped with recirculation, reference theStart-Up: Direct Gas-Fired Heating, Optional Features,Recirculation Operation section in this Installation,Operation and Maintenance Manual for moreinformation. For units equipped with variable air volume,reference the Start-Up: Direct Gas-Fired Heating,Optional Features, Variable Air Volume section in thisInstallation, Operation and Maintenance Manual formore information.With all access panels in place, the fan runningand discharging 70ºF (21ºC) air, connect a U-Tubemanometer to the burner differential sensing probes andmeasure the static pressure across the burner.Proper air velocity over the burner is critical on directgas-fired units. If the air velocity is not within the unitspecifications, the unit will not operate efficiently, mayhave sporadic shutdowns, and may produce elevatedby-products of combustion.The proper static pressure should be between:• Natural Gas:0.625 and 0.675 in. wg (156 and 168 Pa)• Liquid Propane (LP) Gas:0.8 and 0.9 in. wg (200 and 224 Pa)Start-Up: Direct Gas-Fired HeatingAll Units2. Check the Optional High and Low GasPressure SwitchesThe high pressure setting is typically 8 in. wg (2 kPa)and the low pressure is setting is typically 3 in. wg(0.7 kPa). The switches are set at the factory and shouldnot need adjustment. Adjust the setting only if needed.Reference the Pre-Start-Up: Direct Gas-Fired Heating,Gas Train Identification section in this Installation,Operation and Maintenance Manual for the high and lowpressure switch location.The purpose of the high and low gas pressure switchesis to automatically shut down the burner if the inlet gaspressure is too low for the burner to safely light, or if themanifold pressure is too high for the burner to operateproperly.3. Energize the unit control circuits (field-wiringshown on diagram with dashed lines)• Exhaust fan (optional) - Connect terminals R to H• Supply fan - Connect terminals R to G• Heating - Connect terminals R to W14. Verify inlet air sensor (TS4) (if equipped)Set inlet air sensor above the outside air temperature.5. Verify supply fan rotation is correctTo reverse the rotation on three phase units, disconnectand lockout the power, then interchange any two powerleads going to the motor. Check motor amp draw andcompare to motor nameplate Full Load Amperage (FLA).Reduce airflow if amp draw is greater than FLA.For proper unit function and safety, follow the start-upprocedure in the exact order that it is presented.This start-up should begin after all of the installationprocedures and the supply fan start-up have beencompleted.1. Check the Supply Gas PressureCheck the supply gas pressure and compare it withthe unit’s nameplate pressure requirements. Adjustthe supply regulator as needed until the supply gaspressure is within the specified range. The nameplate islocated on the outside of the unit on the control panelside.AdjustableTop BaffleAirflowBurnerAdjustableBottom BaffleBurner and Baffles45670.625 - 0.675 in. wcMeasuring the Pressure DropOuterSensingProbesU-TubeManometerPressureSwitchDirect Gas NameplateTypeof gas MaximumgaspressureMinimum gas pressurefor maximum output |
manualsdatabase
Your AI-powered manual search engine