York ZF150 Installation Manual

Also see for Predator ZF078: Technical guide

518674-YIM-C-0610Johnson Controls Unitary Products 59Adjustment Of Temperature RiseThe temperature rise (the difference of temperature between thereturn air and the heated air from the furnace) must lie within therange shown on the CSA rating plate and the data in Table 9.After the temperature rise has been determined, the CFM canbe calculated as follows:After about 20 minutes of operation, determine the furnacetemperature rise. Take readings of both the return air and theheated air in the ducts (about 6 feet from the furnace) wherethey will not be affected by radiant heat. Increase the blowerCFM to decrease the temperature rise; decrease the blowerCFM to increase the rise (See SUPPLY AIR DRIVEADJUSTMENT).NOTE: Each gas heat exchanger size has a minimumallowable CFM. Below this CFM, the limit will open.Burners/Orifices Inspection/ServicingBefore checking or changing burners, pilot or orifices, CLOSEMAIN MANUAL SHUT-OFF VALVE AND SHUT OFF ALLPOWER TO THE UNIT.1. Open the union fitting just upstream of the unit gas valveand downstream from the main manual shut-off valve inthe gas supply line.2. Remove the screws holding each end of the manifold to themanifold supports.3. Disconnect wiring to the gas valves and spark igniter(s).Remove the manifold & gas valve assembly. Orifices cannow be inspected and/or replaced.To service burners, complete step 4.4. Remove the heat shield on top of the manifold supports.Burners are now accessible for inspection and/orreplacement.NOTE: Reverse the above procedure to replace theassemblies.Make sure that burners are level and seat at the rear of the gasorifice.Figure 32: Typical FlameFigure 33: Typical Gas ValveCharging The UnitAll ZF units use Thermal Expansion Devices. Charge the unit tonameplate charge or 10° subcooling.TroubleshootingHEAT EXCHANGER TUBEBURNER FLAME(BLUE ONLY)IGNITORBURNER BRACKETBURNERGASSUPPLYPIPETroubleshooting of components may require openingthe electrical control box with the power connected tothe unit. Use extreme care when working with livecircuits! Check the unit nameplate for the correct linevoltage and set the voltmeter to the correct range beforemaking any connections with line terminals.For troubleshooting of optional VFD, disconnect allpower to the drive. Be aware that high voltages arepresent in the drive even after power has beendisconnected. Capacitors within the drive must beallowed to discharge before beginning service.When not necessary, shut off all electric power to theunit prior to any of the following maintenanceprocedures so as to prevent personal injury.Label all wires prior to disconnection when servicingcontrols. Wiring errors can cause improper anddangerous operation which could cause injury to personand/or damage unit components. Verify properoperation after servicing.INLETPRESSURETAPHIGH & LOW GAS ADJUSTMENTOUTLETPRESSURETAPMATE-N-LOCKCONNECTORSHI LOONOFFMVCHI