Carrier 50TCA04-A07 - Manual (Page 48)

48
equal to OCSP and Enthalpy = Low then PURGEMP =
100%.
S If the OAT < NTLO then PURGEMP = LTMP (Low
Temperature Minimum Position -- defaults to 10%)
S If the OAT > 65_F or (OAT ≥ NTLO and OAT > OCSP)
or Enthalpy = High then PURGEMP = HTMP (High
Temperature Minimum Position defaults to 35%).
The LTMP and HTMP are user adjustable values from 0
to 100% in the SETPOINT table. Whenever PURGEMP
results in a number greater than 0%, the IAQ
pre--occupancy purge mode will be enabled turning on the
Indoor Fan Relay and setting the economizer IQMP to the
PURGEMP value. When IAQ pre--occupancy mode is not
active PURGEMP = 0%.
Unoccupied Free Cooling — Unoccupied free cool
function will start the indoor fan during unoccupied times
in order to cool the space with outside air. This function is
performed to delay the need for mechanical cooling when
the system enters the occupied period. Depending on how
Unoccupied Free Cooling is configured, unoccupied mode
can occur at any time in the unoccupied time period or 2
to 6 hours prior to the next occupied time. Once the space
has been sufficiently cooled during this cycle, the fan will
be stopped. In order to perform unoccupied free cooling
all of the following conditions must be met:
S NTEN option is enabled in the CONFIG configuration
table
S Unit is in unoccupied state
S Current time of day is valid
S Temperature Compensated Start mode is not active
S COOL mode is not active
S HEAT mode is not active
S SPT reading is available
S OAT reading is available
S Enthalpy is low
S OAT > NTLO (with 1_F hysteresis) and < Max Free Cool
setpoint
If any of the above conditions are not met, Unoccupied
Free Cool mode will be stopped, otherwise, the mode will
be controlled as follows:
The NTFC setpoint (NTSP) is determined as NTSP =
(OCSP + OHSP) / 2
The Unoccupied Free Cool mode will be started when:
SPT > (NTSP + 2_F) and SPT > (OAT + 8_F)
The Unoccupied Free Cool mode will be stopped when:
SPT < NTSP or SPT < (OAT + 3_F)
Temperature Compensated Start — This function will run
when the controller is in unoccupied state and will
calculate early start bias time (SBT) based on space
temperature deviation from occupied setpoints in minutes
per degree. The following conditions will be met for the
function to run:
S Unit is in unoccupied state
S Next occupied time is valid
S Current time of day is valid
S Valid space temperature reading is available (from sensor
or linkage thermostat)
S Cool Start Bias (KCOOL) and Heat Bias Start (KHEAT)
> 0 in the CONFIG configuration table
The SBT is calculated by one of the following formulas
depending on temperature demand:
If SPT > OCSP then SBT = (SPT -- OCSP) * KCOOL
If SPT < OHSP then SPT = (OHSP -- SPT) * KHEAT.
The calculated start bias time can range from 0 to 255
minutes. When SBT is greater than 0 the function will
subtract the SBT from the next occupied time to calculate
a new start time. When a new start time is reached, the
Temperature Compensated Start mode is started. This
mode energizes the fan and the unit will operate as though
it is in occupied state. Once set, Temperature
Compensated Start mode will stay on until the unit returns
to occupied state. If either Unoccupied Free Cool or IAQ
Pre--Occupancy mode is active when Temperature
Compensated Start begins, their mode will end.
Door Switch — The Door Switch function is designed to
disable mechanical heating and cooling outputs when the
REMOCC contact input is closed (in the ON state) after a
programmed time delay. The fan will continue to operate
based on the current mode and the ASHRAE 90.1 Supply
Fan setting. The delay is programmable from 2 to 20
minutes by setting the Remote Cont/Door Switch decision
in the SERVICE table to a value equal to the number of
minutes desired. When the contact is open (in the OFF
state), the PremierLink controller will resume normal
temperature control.
This application is designed for use in schools or other
public places where a door switch can be installed to
monitor the opening of a door for an extended period of
time. The controller will disable mechanical cooling and
heating when the door is open for a programmed amount
of time.
This function can also be used to monitor a high
condensate level switch when installed on a water source
heat pump to disable mechanic cooling in case of a
plugged evaporator condensate pan drain.
Linkage — The Linkage function in the PremierLink
controller is available for applications using a Linkage
thermostat or the 3V control system. If using the Linkage
thermostat, both the PremierLink controller and the stat
must be on the same CCN bus. When used as the air
source for a 3V control system, the PremierLink controller
is not required to be on the same CCN bus but it is
recommended. Linkage will be active when it is initiated
from the Linkage thermostat or the 3V Linkage
Coordinator through CCN communications and requires
no configuration. Only one device can be linked to the
PremierLink controller.
50TC