York P*XU/G9D-UP Installation Instruction

Contents

035-17480-000 Rev. A (800)20 Unitary Products GroupRollout Switch Controls: These controls are mounted onthe burner box assembly. If the temperature in the burnercompartment exceeds its set point, the igniter control and thegas valve are de-energized. The operation of this control indi-cates a malfunction in the combustion air blower, heatexchanger or a blocked vent pipe connection. Correctiveaction is required. This is a manual reset control and must bereset before operation can continue.Pressure Switches: This furnace is supplied with pressureswitches which monitor the flow through the combustion air/vent piping system. These switches de-energize the ignitioncontrol module and the gas valve if any of the following condi-tions are present. Refer to Figure 24 for tubing connections1. Blockage of combustion air piping or terminal:•Low fire (1LP)•High fire (2 LP)2. Blockage of vent piping or terminal:•Low fire (1LP)•High fire (2 LP)3. Failure of combustion air blower motor :•Low fire (1LP)•High fire (2 LP)4. Blockage of condensate drain piping:•Low fire (1LP)•High fire (2 LP).Limit ControlThere are high temperature limit controls located on the fur-nace vestibule panel near the gas valve. These are automaticreset controls that provide over temperature protection due toreduced airflow, such as a dirty filter.START-UP AND ADJUSTMENTSThe initial start-up of the furnace requires the following addi-tional procedures:1. When the gas supply is initially connected to the furnace,the gas piping may be full of air. In order to purge this air,it is recommended that the ground union be looseneduntil the odor of gas is detected. When gas is detected,immediately retighten the union and check for leaks.Allow five minutes for any gas to dissipate before con-tinuing with the start-up procedure.2. The condensate trap must be filled with water before put-ting the furnace into operation. The recommended pro-cedure is as follows:a. Disconnect the condensate drain hose from theinduced draft blower discharge.b. Elevate this hose and fill with water using a funnel.c. Replace the condensate drain hose and clamps.NOTE: If this procedure is not followed, the unit may notproperly drain on initial start up.3. All electrical connections made in the field and in the fac-tory should be checked for proper tightness.IGNITION SYSTEM SEQUENCE1. Turn the gas supply ON at external valve and main gasvalve.2. Set the thermostat above room temperature to call forheat.3. System start-up will occur as follows:a. The induced draft blower motor will start and oper-ate on low speed. Shortly after venter start-up, thehot surface igniter will glow for about 17 seconds.b. The ignition module will energize (open) the maingas valve on low fire for seven seconds.c. After flame is established, the supply air blower willstart in about 30 seconds.FIGURE 24 : Pressure Switch Tubing RoutingINDUCTED DRAFTBLOWERBURNER BOXUPFLOW1LP 2LPBe sure proper ventilation is available to dilute andcarry away any vented gas.Perform the following procedures only after thecondensate trap has been properly piped to adrain connection using the procedure in thisinstruction.