York DM036 Installation Manual

Also see for DM 036: Technical guide

Contents

York DM036 Installation Manual Manual pdf 40 page image

5011492-XIM-B-081540 Johnson Controls Unitary ProductsTemperature LimitsThe primary limit is located such that the temperature sensitiveswitch can sense the temperature of the heat exchanger tubes.On single stage models the limit is mounted to the condenserpartition panel. On two stage models the limit is mounted justabove the inlet of the heat exchanger tubes on the right side. Ifa primary limit (LS) fault occurs (the primary limit opens due toexcessive heat exchanger temperature), then the ICB will flashthe appropriate code (Table 29) and monitor the primary limit.The UCB will energize the indoor blower and the ICB willenergize the draft motor while the primary limit is open. Whenthe primary limit closes and the call for heat still exists, the ICBwill start the ignition sequence over and the UCB will de-energize the blower for 45 seconds. However, the auxiliary limitis in series with the primary limit and it takes first control. If theexcessive heat has been high enough to cause the auxiliarylimit (AUX) to open, then the ICB will flash the primary limit codebut the furnace will not retry ignition during the same call forheat. The auxiliary limit is of the manual reset type and ismounted in the upper right hand corner of the panel betweenthe burner manifold and the flue gas collector box just behindthe draft motor. If the auxiliary switch has opened, then specialattention should be paid to the primary limit as it may be faultyas well. However, the auxiliary switch is sized such that multipletrips of the primary limit due to complete blower failure willcause enough heat to build up and trip the auxiliary.If the primary limit opens three times within one hour, then theUCB will lock on the indoor blower and flash a code on theSimplicity Lite Control (Table 28) or sends error message tothe LCD Simplicity SE Control.Gas ValveThe UCB monitors the gas valve (GV). Any time the UCBsenses voltage at the GV without a call for heat for a continuousfive-minute period, the UCB will lock on the indoor blower and aflash code on the UCB is initiated (Table 28). When the UCB nolonger senses voltage at the GV the UCB will de-energize theindoor blower after the expiration of the indoor blower heatingoff delay.If the voltage has been sensed at the GV for at least 15seconds during the fan on delay for heating and the UCB nolonger senses voltage at the GV (W1 call for heat removed oran ICB fault exists), then the UCB forces the indoor blower onfor the indoor blower heating off delay.The gas valve is of the redundant type. If for any reason themain gas valve fails in the open position, then the redundantvalve ahead of the main gas valve will shut off the flow of gas toboth the pilot and main gas valves.Centrifugal SwitchThe centrifugal switch is mounted on the end of the draft motorand it is an integral part of the motor assembly. On a call forheat, the ICB checks the centrifugal switch (CS) for open statebefore it energizes the draft motor. If it is closed, then the ICBwill lock out the furnace and flash a code (Table 29). If open,then the ICB will energize the draft motor and verify that theswitch closes before initiating the purging and ignitionsequence. If at any time during furnace operation thecentrifugal switch opens, then the ICB will de-energize the pilotand main gas valves and monitor the centrifugal switch. If thecentrifugal switch closes and the call for heat still exists, thenthe ICB will retry the purging and ignition sequence.Rollout SwitchThis temperature sensitive switch is located in the burnervestibule just above the right hand side of the burner assembly.In the event of the flame spilling out into the burner manifoldarea the rollout switch will open, the ICB will close both themain and pilot gas valves and flash a code (Table 29). The ICBwill not retry the ignition sequence during the same call for heat.Flame Sense CircuitThe flame sensor is mounted on the left hand side of the burnerassembly and is positioned such that the pilot flame surroundsthe tip of the sensor. On a call for heat the ICB checks for theflame sense circuit to be open. If open, then the ICB initiates thepurging and ignition sequence. Once the pilot flame is present,the ICB monitors the flame sense circuit for pilot flame stability.If the pilot flame is unstable or lost completely, then the ICB willimmediately close both the pilot and main gas valves. The ICBwill retry the purging and ignition sequence. If the flame isunstable or lost more than 16 times during the same call forheat, then the ICB will lock out furnace operation for 5 minutes.Flash Codes or Error MessagesThe UCB will initiate a flash code associated with errors withinthe system. Refer to flash a code on the Simplicity Lite Control(See Table 28) or sent error message to the LCD Simplicity SEControl.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.Table 25: Limit Control SettingUnit(Tons)Capacity, MBH Limit Control Opens, °FInput Output Direct Drive Belt Drive3 15 (50) 12 (40) 115 (240) -4 22 (75) 18 (60) 99 (210) -5, 6.3 29 (100) 29 (80) - 99 (210)Table 26: Gas Heat Anticipator SetpointsGas Valve Anticipator SetpointHoneywell VR8204M 0.60 ampWhite-Rodgers 36E36 0.54 amp