York DM090 Installation Manual

Also see for PREDATOR DM 090: Installation manual Technical guide Installation manual Technical guide Installation instruction

Contents

127408-YIM-B-060644 Unitary Products GroupAny time the UCB senses voltage at the GV without a call forheat for a continuous five-minute period, the UCB will lock-onthe indoor blower and a flash code is initiated (Table 52).When voltage is no longer sensed at the GV, the UCB will de-energize the indoor blower following the elapse of the fan offdelay for heating.If voltage has been sensed at the GV for at least 15 secondsduring the fan on delay for heating and GV voltage or “W1” islost, the indoor blower is forced on for the length of the fan offdelay for heating.During a call for heat, if the UCB does not sense voltage atthe GV for a continuous five-minute period the UCB will ini-tiate a flash code (Table 52). The indoor blower motor will notbe locked-on while there is no GV voltage.SAFETY CONTROLSThe UCB monitors the temperature limit switch of electricheat units.The control circuit includes the following safety controls:LIMIT SWITCH (LS)This control is located inside the heater compartment and isset to open at the temperature indicated in the Electric HeatLimit Setting Table 44. It resets automatically. The limit switchoperates when a high temperature condition, caused by inad-equate supply air flow occurs, thus shutting down the heaterand energizing the blower.AUXILIARY LIMIT SWITCH (ALS)This control is located inside the supply air compartment andis set to open at the temperature indicated in the Gas HeatLimit Control Settings Table 46. It resets manually. The limitswitch operates when a high temperature condition, causedby inadequate supply air flow occurs, thus shutting down theheater and energizing the blower.The auxiliary limit switch is wired in series with the limitswitch. As such, the UCB cannot distinguish the auxiliary limitand the gas heat limit switch operation except the auxiliary ismanual reset. Consequently, the control will respond in thesame manner as outlined above under “Limit Switch”.The 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-ener-gized, the ignition cycle is aborted, and the ICB flashes theappropriate code. See Table 53 Ignition Control Flash Codes.The draft motor is energized until the pressure switch closesor “W1” is lost.ROLLOUT SWITCH (ROS)The rollout switch is wired in series with the pressure switch.As such, the ICB cannot distinguish the rollout switch opera-tion from that of the pressure switch.Consequently, the control will only respond in the same man-ner as outlined above under “Pressure Switch”. An open roll-out will inhibit 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 UCB will initiate a flash code associated with errorswithin the system. Refer to UNIT CONTROL BOARD FLASHCODES Table 52.RESETSRemove the call for heating by lowering the thermostat set-ting lower than the conditioned space temperature. Thisresets any flash codes.GAS HEAT ANTICIPATOR SETPOINTSIt is important that the anticipator setpoint be correct. Toohigh of 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 47 for the required gasheat anticipator setting.TABLE 46: GAS HEAT LIMIT SETTINGS**. Rollout = 300°F (148.9°C), Auxiliary Limit = 200°F (93.3°C)Unit Main Limit SettingSize Opt. Natural Gas LPGDM090 10 165°F (73.9°C) 175°F (79.4°C)15 165°F (73.9°C) 185°F (85°C)DM120 15 195°F (90.5°C) 195°F (90.5°C)DM150 15 195°F (90.5°C) 195°F (90.5°C)TABLE 47: GAS HEAT ANTICIPATOR SETPOINTSSETTING, AMPSW1 W20.65 0.1FIGURE 28 - TYPICAL FLAMEHEATEXCHANGERTUBEGASSUPPLYPIPEBURNERBURNERBRACKETIGNITORBURNERFLAME(BLUEONLY)