York AVV25B Installation Manual

5292157-UIM-B-0317Johnson Controls Unitary Products 15SECTION XII: AIRFLOW AND COMFORTSETTING SELECTIONAIRFLOW SELECTION AT THERMOSTATInputs to air handler control board come from the thermostat which arecommunicated from the main control of the outdoor unit. This maintainsproper sensible/latent balance during cooling and proper dischargetemperature during heating.Proper indoor unit airflow is determined by the system and requires noinitial set-up by the installing contractor. If the indoor unit is usingelectric heat, the unit must have the electric heat airflow set at the airhandler control board HEAT jumper. Refer to electric heat minimum fanspeed and the air flow data tables for proper selection when operatingthe air handler with the electric heat section.After the system is started during the initial set-up process using theHx TM thermostat, additional fine tuning of the airflow is accomplished byselecting one of the climate setting profiles. The comfort profilesinclude: humid, dry or normal. Select the one that best reflects theoutdoor environment where the conditioned space is located. Thisselection adjusts how the indoor blower and the compressor worktogether to manage temperature and humidity.The normal comfort setting operates the indoor blower speed ascommanded by the outdoor unit. The humid comfort setting eitherdecreases the commanded indoor blower speed or increases thecompressor speed depending on the demand to best manage humidity.The dry comfort setting increases the commanded indoor blower speedin relation to the compressor speed to optimize sensible cooling.Additional airflow fine tune adjustments are available using the Hxthermostat. Refer to the Hx thermostat manual for additional detail andthe selectable “Blower Operating Profiles” available.These variable speed air handlers are designed to deliver constant air-flow (CFM) up to a maximum of 0.8 inches external static pressure(ESP) in the ductwork. Therefore, if too many supply registers areclosed, a filter becomes clogged, or there is a restriction in theductwork, the motor automatically operates at a higher speed to com-pensate for the higher ESP. This may result in a higher operating soundlevel, a higher power consumption, and have a negative impact on theservice life of the blower motor.To Set Cooling Airflow:The modulating outdoor AC or HP operate the indoor blower in conjunc-tion with the outdoor unit compressor speed.To Set Heat Pump Airflow:The modulating outdoor AC or HP operate the indoor blower in conjunc-tion with the outdoor unit compressor speed.To Set Electric Heat Airflow:The blower speed required for electric heat is different than cooling.Refer to Table 14 for the possible CFM selections. Refer to Table 7 forthe minimum required airflow for the electric heater installed. Find thedesired airflow in Table 14 for heat. Set the HEAT jumper on the controlas indicated in Table 14.Blower Ramp-Up /Ramp-Down:To minimize the sound made by the blower when it speeds up or slowsdown, the blower will slowly ramp up or down from one speed toanother. Changes in blower speed during A/C or heat pump heating cantake up to 30 seconds. Changes in blower speed during electric resis-tance heating can take up to 15 seconds.BLOWER OPERATING PROFILESThe blower operating profiles are to be selected on the Hx TMcommunicating thermostat. This controls blower operation at thebeginning and the end of a demand.NormalThe normal setting provides a ramp-up from zero airflow to full capacityand a ramp-down from full capacity back to zero airflow.HumidThe humid setting is best-suited for installations where the humidity isfrequently very high during cooling season, such as in the southern partof the country. On a call for cooling, the blower will ramp up to 50% offull capacity and will stay there for two minutes, then will ramp up to82% of full capacity and will stay there for five minutes, and then willramp up to full capacity, where it will stay until the wall thermostat is sat-isfied.DryThe dry setting is best suited to parts of the country where excessivehumidity is not generally a problem, where the summer months are usu-ally dry. On a call for cooling the motor will ramp up to full capacity andwill stay there until the thermostat is satisfied. At the end of the coolingcycle, the blower will ramp down to 50% of full capacity where it will stayfor 60 seconds. Then it will ramp down to zero.TemperateThe temperate setting is best suited for most of the country, where nei-ther excessive humidity nor extremely dry conditions are the norm. Ona call for cooling, the motor will ramp up to 63% of full capacity and willstay there for 90 seconds, then will ramp up to full capacity. At the endof the cooling cycle, the motor will ramp down to 63% of full capacityand will stay there for 30 seconds, then will ramp down to zero.NOTICEIncorrect airflow and comfort settings may result in decreased systemefficiency and performance.