Carrier AQUAZONE 50PSH Installation And Service Instructions Manual

44NOTE: Scheduling can either be controlled via the unit or theBAS, but not both.INDOOR FAN — The indoor fan will operate in any one ofthree modes depending on the user configuration selected.Fan mode can be selected as Auto, Continuous, or AlwaysOn. In Auto mode, the fan is in intermittent operation duringboth occupied and unoccupied periods. Continuous fan modeis intermittent during unoccupied periods and continuous dur-ing occupied periods. Always On mode operates the fan con-tinuously during both occupied and unoccupied periods. In thedefault mode, Continuous, the fan will be turned on wheneverany one of the following is true:• The unit is in occupied mode as determined by its occu-pancy status.• There is a demand for cooling or heating in the unoccu-pied mode.• There is a call for dehumidification (optional).When power is reapplied after a power outage, there will bea configured time delay of 5 to 600 seconds before starting thefan. There are also configured fan delays for Fan On and FanOff. The Fan On delay defines the delay time (0 to 30 seconds;default 10) before the fan begins to operate after heating orcooling is started while the Fan Off delay defines the delaytime (0 to 180 seconds; default 45) the fan will continue to op-erate after heating or cooling is stopped. The fan will continueto run as long as the compressors, heating stages, or the dehu-midification relays are on. If the SPT failure alarm or conden-sate overflow alarm is active; the fan will be shut down imme-diately regardless of occupancy state or demand.Automatic Fan Speed Control — The WSHP Open controlleris capable of controlling up to three fan speeds using the ECM(electronically commutated motor). The motor will operate atthe lowest speed possible to provide quiet and efficient fan op-eration with the best latent capability. The motor will increasespeed if additional cooling or heating is required to obtain thedesired space temperature set point. The control increases themotor's speed as the space temperature rises above the coolingor below the heating set point. The amount of space tempera-ture increase above or below the set point required to increasethe fan speed is user configurable in the set point. Also, thecontrol will increase the fan speed as the supply-air tempera-ture approaches the configured minimum or maximum limits.Fan Speed Control (During Heating) — Whenever heat is re-quired and active, the control continuously monitors the sup-ply-air temperature to verify it does not rise above the config-ured maximum heating SAT limit (110 F default). As the SATapproaches this value, the control will increase the fan speed asrequired to ensure the SAT will remain within the limit. Thisfeature provides the most quiet and efficient operation by oper-ating the fan at the lowest speed possible.Fan Speed Control (During Cooling) — Whenever mechani-cal cooling is required and active, the control continuouslymonitors the supply-air temperature to verify it does not fall be-low the configured minimum cooling SAT limit (50 F default).As the SAT approaches this value, the control will increase thefan speed as required to ensure the SAT will remain within thelimit. The fan will operate at lowest speed to maximize latentcapacity during cooling.COOLING — The WSHP Open controller will operate one ortwo stages of compression to maintain the desired cooling setpoint. The compressor outputs are controlled by the PI (propor-tional-integral) cooling loop and cooling stages capacity algo-rithm. They will be used to calculate the desired number ofstages needed to satisfy the space by comparing the space tem-perature (SPT) to the appropriate cooling set point. The waterside economizer, if applicable, will be used for first stage cool-ing in addition to the compressor(s). The following conditionsmust be true in order for the cooling algorithm to run:• Cooling is set to Enable.• Heating mode is not active and the compressor timeguard has expired.• Condensate overflow input is normal.• If occupied, the SPT is greater than the occupied coolingset point.• Space temperature reading is valid.• If unoccupied, the SPT is greater than the unoccupiedcooling set point.• If economizer cooling is available and active and theeconomizer alone is insufficient to provide enough cool-ing.• OAT (if available) is greater than the cooling lockouttemperature.If all the above conditions are met, the compressors will beenergized as required, otherwise they will be deenergized. Ifcooling is active and should the SAT approach the minimumSAT limit, the fan will be indexed to the next higher speed.Should this be insufficient and if the SAT falls further (equal tothe minimum SAT limit), the fan will be indexed to the maxi-mum speed. If the SAT continues to fall 5 F below the mini-mum SAT limit, all cooling stages will be disabled.During Cooling mode, the reversing valve output will beheld in the cooling position (either B or O type as configured)even after the compressor is stopped. The valve will not switchposition until the Heating mode is required.The configuration screens contain the minimum SATparameter as well as cooling lockout based on outdoor-airtemperature (OAT) Both can be adjusted to meet variousspecifications.There is a 5-minute off time for the compressor as well as a5-minute time delay when staging up to allow the SAT toachieve a stable temperature before energizing a second stageof capacity. Likewise, a 45-second delay is used when stagingdown.After a compressor is staged off, it may be restarted againafter a normal time-guard period of 5 minutes and if the sup-ply-air temperature has increased above the minimum supply-air temperature limit.The WSHP Open controller provides a status input to moni-tor the compressor operation. The status is monitored to deter-mine if the compressor status matches the commanded state.This input is used to determine if a refrigerant safety switch orother safety device has tripped and caused the compressor tostop operating normally. If this should occur, an alarm will begenerated to indicate the faulted compressor condition.HEATING — The WSHP Open controller will operate one ortwo stages of compression to maintain the desired heating setpoint. The compressor outputs are controlled by the heating PI(proportional-integral) loop and heating stages capacity algo-rithm. They will be used to calculate the desired number ofstages needed to satisfy the space by comparing the space tem-perature (SPT) to the appropriate heating set point. The follow-ing conditions must be true in order for the heating algorithm torun:• Heating is set to Enable.• Cooling mode is not active and the compressor timeguard has expired.• Condensate overflow input is normal.• If occupied, the SPT is less than the occupied heating setpoint.• Space temperature reading is valid.• If unoccupied, the SPT is less than the unoccupied heat-ing set point.• OAT (if available) is less than the heating lockouttemperature.If all the above conditions are met, the heating outputs willbe energized as required, otherwise they will be deenergized. Ifthe heating is active and should the SAT approach the maxi-mum SAT limit, the fan will be indexed to the next higher°