Carrier 58MVP Installation, Start-up, And Operating Instructions Manual

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Carrier 58MVP Installation, Start-up, And Operating Instructions Manual Manual pdf 38 page image

The blower motor BLWM will revert to continuous-blower airflowafter the heating cycle is completed. In high-heat, the furnacecontrol CPU will drop the blower motor BLWM to low-heatairflow during the selected blower-OFF delay period beforetransitioning to continuous-blower airflow.When the thermostat ″calls for high-cooling″, the blower motorBLWM will operate at high-cooling airflow. When the thermostatis satisfied, the blower motor BLWM will operate an additional 90seconds at high-cooling airflow before transitioning back tocontinuous-blower airflow.When the R to G circuit is opened, the blower motor BLWM willcontinue operating for an additional 5 seconds, if no other functionrequires blower motor BLWM operation.Continuous Blower Speed Selection from ThermostatTo select different continuous-blower speeds from the roomthermostat, momentarily turn off the FAN switch or push-button on the room thermostat for 1-3 seconds after the blowermotor BLWM is operating. The furnace control CPU will shiftthe continuous-blower airflow from the factory setting to thenext highest CF selection airflow as shown in Fig. 35.Momentarily turning off the FAN switch again at the thermo-stat will shift the continuous-blower airflow up one moreincrement. If you repeat this procedure enough, you willeventually shift the continuous-blower airflow to the lowestCF selection as shown in Fig. 35. The selection can bechanged as many times as desired and is stored in the memoryto be automatically used following a power interruption.HEAT PUMPSee Fig. 41-44 for thermostat connections.When installed with a heat pump, the furnace control automaticallychanges the timing sequence to avoid long blower off times duringdemand defrost cycles. Whenever W/W1 is energized along withY1 or Y/Y2, the furnace control CPU will transition to or bring onthe blower motor BLWM at cooling airflow, low-heat airflow, orthe midrange airflow, whichever is the lowest. The blower motorBLWM will remain on until the main burners ignite, then shut OFFand remain OFF for 25 seconds before coming back on at heatingairflow. When the W/W1 input signal disappears, the furnacecontrol begins a normal inducer post-purge period while changingthe blower airflow. If Y/Y2 input is still energized, the furnacecontrol CPU will transition the blower motor BLWM airflow tocooling airflow. If Y/Y2 input signal disappears and the Y1 inputis still energized, the furnace control CPU will transition theblower motor BLWM to low-cooling airflow. If both the Y1 andY/Y2 signals disappear at the same time, the blower motor BLWMwill remain on at low-heat airflow for the selected blower-OFFdelay period. At the end of the blower-OFF delay, the blowermotor BLWM will shut OFF unless G is still energized, in whichcase the blower motor BLWM will operate at continuous blowerairflow.COMPONENT TESTThe furnace features a component test system to help diagnose asystem problem in the case of a component failure. To initiate thecomponent test procedure, ensure that there are no thermostatinputs to the control and all time delays have expired. Turn onsetup switch SW1-6 (See Fig. 25.)NOTE: The component test feature will not operate if the controlis receiving any thermostat signals or until all time delays haveexpired.The component test sequence is as follows:a. The furnace control CPU turns the inducer motor IDM ONat medium speed and keeps it ON through step c.b. After waiting 15 seconds, the furnace control CPU turnsthe hot surface igniter ON for 15 seconds, then OFF.c. The furnace control CPU then turns the blower motorBLWM ON at midrange airflow for 15 seconds, then OFF.d. After shutting the blower motor BLWM OFF, the furnacecontrol CPU shuts the inducer motor IDM OFF.NOTE: The EAC terminals are energized when the blower isoperating.After the component test is completed, 1 or more status codes (11,25, 41, or 42) will flash. See Service Label on blower access panelor Service/Status Code Instructions for explanation of status codes.NOTE: To repeat component test, turn setup switch SW1-6 toOFF and then back ON.Step 6—AdjustmentsSET GAS INPUT RATEFurnace gas input rate on rating plate is for installations at altitudesup to 2000 ft.In the U.S.A., the input rating for altitudes above 2000 ft must bereduced by 2 percent for each 1000 ft above sea level.In Canada, the input rating must be derated by 5 percent foraltitudes of 2000 ft to 4500 ft above sea level.Adjust manifold pressure to obtain input rate.Furnace input rate must be within ±2 percent of input rate onfurnace rating plate.1. Determine natural gas orifice size and manifold pressure forcorrect input.a. Obtain average heat value (at installed altitude) from localgas supplier.b. Obtain average specific gravity from local gas supplier.c. Verify furnace model. Table 12 can only be used for model58MVP Furnaces.d. Find installation altitude in Table 12.NOTE: For Canadian altitudes of 2000 to 4500 ft, use U.S.A.altitudes of 2001 to 3000 ft in Table 12.e. Find closest natural gas heat value and specific gravity inTable 12.f. Follow heat value and specific gravity lines to point ofintersection to find orifice size and low- and high-heatmanifold pressure settings for proper operation.EXAMPLE: (0—2000 ft altitude)Heating value = 1050 Btu/cu ftSpecific gravity = 0.62Therefore: Orifice No. 45Manifold pressure: 3.8-in. wc for high heat1.6-in. wc for low heat* Furnace is shipped with No. 45 orifices. In this example,all main burner orifices are the correct size and do not needto be changed to obtain proper input rate.g. Check and verify burner orifice size in furnace. NEVERASSUME ORIFICE SIZE; ALWAYS CHECK ANDVERIFY.38