Carrier 50PCH specifications There is a call for dehumidification optional

optional CO2 IAQ (indoor air quality) sensor mounted in the space can maximize the occupant comfort. The WSHP Open controller has its own hardware clock that is automatically set when the heat pump software is downloaded to the board. Oc- cupancy types are described in the scheduling section below. The following sections describe the functionality of the WSHP Open multi-protocol controller. All point objects referred to in this sequence of operation will be referenced to the objects as viewed in the BACview6 handheld user interface.

SCHEDULING — Scheduling is used to start/stop the unit based on a time period to control the space temperature to spec- ified occupied heating and cooling set points. The controller is defaulted to control by occupied set points all the time, until ei- ther a time schedule is configured with BACview6, Field Assis- tant, i-Vu®Open, or a third party control system to enable/dis- able the BAS (Building Automation System) on/off point. The local time and date must be set for these functions to operate properly. The occupancy source can be changed to one of the following:

Occupancy Schedules — The controller will be occupied 24/7 until a time schedule has been configured using either Field Assistant, i-Vu Open, BACview6 or a third party control system to enable/disable the BAS on/off point. The BAS point can be disabled by going to Config, then Unit, then Occupancy Sched- ules and changing the point from enable to disable then click- ing OK.

NOTE: This point must be enabled in order for the i-Vu Open, Field Assistant, or BACview6 control system to assign a time schedule to the controller.

Schedule_schedule — The unit will operate according to the schedule configured and stored in the unit. The schedule is accessible via the BACview6 Handheld tool, i-Vu Open, or Field Assistant control system. The daily schedule consists of a start/stop time (standard or 24-hour mode) and seven days of the week, starting with Monday and ending on Sunday. To enter a daily schedule, navigate to Config, then Sched, then enter BACview6 Admin Password (1111), then go to schedule_schedule. From here, enter either a Weekly or Excep- tion schedule for the unit.

Occupancy Input Contact — The WSHP Open controller has the capability to use an external dry contact closure to deter- mine the occupancy status of the unit. The Occupancy Sched- ules will need to be disabled in order to utilize the occupancy contact input.

NOTE: Scheduling can only be controlled from one source. BAS (Building Automation System) On/Off — A BAS system that supports network scheduling can control the unit through a network communication and the BAS scheduling function once the Occupancy Schedules have been disabled.

NOTE: Scheduling can either be controlled via the unit or the BAS, but not both.

INDOOR FAN — The indoor fan will operate in any one of three modes depending on the user configuration selected.

Fan mode can be selected as Auto, Continuous, or Always On. In Auto mode, the fan is in intermittent operation during both occupied and unoccupied periods. Continuous fan mode is 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 the default mode, Continuous, the fan will be turned on whenever any 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 be a configured time delay of 5 to 600 seconds before starting the

fan. There are also configured fan delays for Fan On and Fan Off. The Fan On delay defines the delay time (0 to 30 seconds; default 10) before the fan begins to operate after heating or cooling is started while the Fan Off delay defines the delay time (0 to 180 seconds; default 45) the fan will continue to op- erate after heating or cooling is stopped. The fan will continue to 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.

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 SAT approaches this value, the control will increase the fan speed as required to ensure the SAT will remain within the limit. This feature 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 continuously monitors 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 the fan speed as required to ensure the SAT will remain within the limit. The fan will operate at lowest speed to maximize latent capacity during cooling.

COOLING — The WSHP Open controller will operate one or two stages of compression to maintain the desired cooling set point. 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 of stages needed to satisfy the space by comparing the space tem- perature (SPT) to the appropriate cooling set point. The water side economizer, if applicable, will be used for first stage cool- ing in addition to the compressor(s). The following conditions must be true in order for the cooling algorithm to run:

•Cooling is set to Enable.

•Heating mode is not active and the compressor time guard has expired.

•Condensate overflow input is normal.

•If occupied, the SPT is greater than the occupied cooling set point.

•Space temperature reading is valid.

•If unoccupied, the SPT is greater than the unoccupied cooling set point.

•If economizer cooling is available and active and the economizer alone is insufficient to provide enough cooling.

•OAT (if available) is greater than the cooling lockout temperature.

If all the above conditions are met, the compressors will be energized as required, otherwise they will be deenergized. If cooling is active and should the SAT approach the minimum SAT limit, the fan will be indexed to the next higher speed. Should this be insufficient and if the SAT falls further (equal to the 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 be held in the cooling position (either B or O type as configured) even after the compressor is stopped. The valve will not switch position until the Heating mode is required.

The configuration screens contain the minimum SAT parameter as well as cooling lockout based on outdoor-air temperature (OAT) Both can be adjusted to meet various specifications.

There is a 5-minute off time for the compressor as well as a 5-minute time delay when staging up to allow the SAT to achieve a stable temperature before energizing a second stage

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