York ZF150 Installation Manual

Also see for Predator ZF078: Technical guide

518674-YIM-C-061056 Johnson Controls Unitary ProductsThe ICB monitors the Pressure and Rollout switches of gasheat units.The control circuit includes the following safety controls:Pressure Switch (PS)Once the draft motor has reached full speed and closes thepressure switch during a normal ignition sequence, if thepressure sw opens for 2 seconds, the GV will be de-energized,the ignition cycle is aborted, and the ICB flashes theappropriate code. See Table 31 Ignition Control Flash Codes.The draft motor is energized until the pressure switch closes or“W1” is lost.Rollout Switch (ROS)The rollout switch is wired in series with the pressure switch. Assuch, the ICB cannot distinguish the rollout switch operationfrom that of the pressure switch.Consequently, the control will only respond in the same manneras outlined above under “Pressure Switch”. An open rollout willinhibit the gas valve from actuating.Internal Microprocessor FailureIf the ICB detects an internal failure, it will cease all outputs,ignore inputs, and display the proper flash code for controlreplacement. The ICB remains in this condition until replaced.Flash CodesThe ICB will initiate a flash code associated with errors withinthe system. Refer to IGNITION CONTROL FLASH CODESTable 31.ResetsRemove the call for heating by lowering the thermostat settinglower than the conditioned space temperature. This resets anyflash codes.Gas Heat Anticipator SetpointsIt is important that the anticipator setpoint be correct. Too highof a setting will result in longer heat cycles and a greatertemperature swing in the conditioned space. Reducing thevalue below the correct setpoint will give shorter “ON cyclesand may result in the lowering of the temperature within theconditioned space. Refer to Table 26 for the required gas heatanticipator setting.Start-Up (Cooling)Prestart Check ListAfter installation has been completed:1. Check the electrical supply voltage being supplied. Be surethat it is the same as listed on the unit nameplate.2. Set the room thermostat to the off position.3. Turn unit electrical power on.4. Set the room thermostat fan switch to on.5. Check indoor blower rotation.• If blower rotation is in the wrong direction. Refer toPhasing Section in general information section.Check blower drive belt tension.6. Check the unit supply air (CFM).7. Measure evaporator fan motor's amp draw.8. Set the room thermostat fan switch to off.9. Turn unit electrical power off.Operating Instructions1. Turn unit electrical power on.NOTE: Prior to each cooling season, the crankcase heatersmust be energized at least 10 hours before the systemis put into operation.2. Set the room thermostat setting to lower than the roomtemperature.3. First stage compressors will energize after the built-in timedelay (five minutes).4. The second stage of the thermostat will energize secondstage compressor if needed.Post Start Check List1. Verify proper system pressures for both circuits.2. Measure the temperature drop across the evaporator coil.Start-Up (Gas Heat)Pre-Start Check ListComplete the following checks before starting the unit.1. Check the type of gas being supplied. Be sure that it is thesame as listed on the unit nameplate.2. Make sure that the vent outlet and combustion air inlet arefree of any debris or obstruction.Table 26: Gas Heat Anticipator SetpointsSETTING, AMPSW1 W20.65 0.1