Carrier AQUAZONE 50PEC09-18 User Manual

Page 41

application, all compressor relays and related functions will

track with their associated DIP switch 2 on S1.
NIGHT LOW LIMIT (NLL) STAGED HEATING — In NLL

staged Heating mode, the override (OVR) input becomes

active and is recognized as a call for heating and the control

will immediately go into a Heating Stage 1 mode. With an

additional 30 minutes of NLL demand, the control will go into

Heating Stage 2 mode. With another additional 30 minutes of

NLL demand, the control will go into Heating Stage 3 mode.

Units with WSHP Open Multiple Protocol —

The WSHP Open multi-protocol controller will control me-

chanical cooling, heating and waterside economizer outputs

based on its own space temperature input and set points. An

optional CO

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 BACview

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 BACview

, 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, BACview

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 BACview

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 BACview

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 BACview

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 cool-

ing.

• 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