33
Table 41 — Configuring Head Pressure Control (Motormaster Control)
*If value changed, enable Data Reset before leaving
.
TRANSDUCERS AND SUCTION THERMISTORS —
The Transducers and Suction Thermistors function allows the
control to read pressure transducers as valid inputs, replacing
the condenser coil thermistor and low pressure switch inputs at
Channels 3, 4, 5, and 6.
The control options module (available as a factory-installed
option or field-installed accessory on size 034-074 units and is
standard on 078-104 units) and pressure transducers are
required.
Sequence of Operation — The control will read channels 3
and 4 as Discharge Pressure Transducer inputs. Alarms 76 and
77 (High Discharge Pressure) will be permitted. The control
will read Channels 5 and 6 as Suction Pressure Transducer in-
puts. Alarms 74 and 75 (Low Pressure), Alarms 80 and 81
(Low Saturated Suction Temperature), Alarms 82 and 83 (High
Superheat), and Alarms 84 and 85 (Low Superheat) will be
permitted.
Configuration — To configure:
1. Enable Transducer Inputs. Press
to enter the
subfunction. Scroll down to TRNS. Press to
enable. Enable Data Reset.
2. Enable Suction Thermistors. Press
to enter the
subfunction. Scroll down to SUSN. Press
to
enable.
Carrier Comfort Network (CCN) Group —
This group includes Demand Limit control and Digital Air
Volume (DAV) application.
DEMAND LIMIT — The Demand Limit mode limits stages
of cooling capacity, resulting from a signal (“Redline Alert” or
“Loadshed”) from the CCN. The “Network Loadshed” option
with CCN is required. Demand Limit is Mode 22.
The CCN ComfortWORKS® package is required.
Sequence of Operation
Redline Alert — When a Redline alert is received from the
CCN, the maximum stage of capacity is set equal to the current
stage of operation. If the unit is not operating when alert signal
is received, capacity stage will be set at zero for 15 minutes,
then restart permitted as normal.
Loadshed — At a Loadshed command from the CCN, the con-
trol will reduce present maximum stage (determined at Redline
Alert) to user-defined percentage of present maximum stage. If
unit at zero already, unit will remain at zero for 15 minutes,
then control will permit unit to climb to user-defined percent-
age of maximum.
Example — Maximum stages for unit size is 11 and Demand
Limit set point is 40%. At a Redline Alert signal, the unit is
currently operating at 10 stages (this becomes the new maxi-
mum stages value). At a Demand Limit signal, the maximum
number of stages is reduced by the user-defined set point limit
(0.40 x 10 = 4 stages permitted). Unit operation will continue
with the number of stages limited to reduced value until the
Loadshed signal is cleared (removed) by CCN.
The Loadshed mode is limited to 1 hour. If the Loadshed
mode is not cleared by the Loadshed option before the 1-hour
limit expires, the mode is automatically cleared and unit opera-
tion will return to normal.
Configuration — To configure:
1. Enable Demand Limit. Press
to enter the sub-
function. Scroll down to DLEN. Press
to
enable.
2. Select Loadshed Groups. Press
to enter the
subfunction. Scroll down to LSGP. Coordinate Group
selection with CCN Loadshed Module equipment
schedules. Default is group 1. Range is 1 to 16.
3. Specify Demand Limit Set Point. Press
to
enter the subfunction. Scroll down to LSP. The default
is 50%. The range is 0 to 100%.
DIGITAL AIR VOLUME (DAV) — Carrier rooftop units
with PIC may also have a communication linkage with the
VAV terminal units in a particular application. This linkage is
called the DAV linkage. The DAV mode indicates the unit is
being controlled through a CCN network and is connected to
DAV system. Digital Air Volume (DAV) is Mode 39. The
ComfortWORKS software system is required. The CCN must
be connected to PSIO1, COMM1 port.
Linkage Data and Operation — The values from the Terminal
System Manager (TSM) which are used as linkage data by the
rooftop PIC control are found in Table 42.
Table 42 — TSM Linkage Codes
Cooling/Heating Routines — When the rooftop unit PIC is
part of a DAV system, the rooftop unit PIC utilizes information
supplied by the TSM to control cooling, heating, and econo-
mizer routines instead of using its own return air and space
temperature sensors. The AOHS, AOCS, AUHS, and AUCS
from the TSM are used instead of the rooftop unit PIC config-
ured set points. The rooftop unit uses the occupancy status in-
formation through the communication linkage, such as NEX-
TOCCT and NEXTUNOT, instead of its internal occupancy
schedule
VAV Systems — During occupied and biased occupied peri-
ods on VAV systems, the rooftop unit PIC uses the AOZT from
the TSM to replace the rooftop unit PIC return-air temperature
sensor value. During unoccupied periods, the rooftop unit PIC
uses the AZT from the TSM instead of the rooftop unit PIC
space temperature and return-air temperature sensor values.
DESCRIPTION
HOW TO CONFIGURE AT HSIO
SET POINT
RANGE
Disable ‘‘Motormaster’’
MMAS
Disable = 0; Enable = 1
Adjust Head Pressure Set Point
HPSP
80 to 150 F (27 to 65 C)*
ENTER
ENTER
EM
DEFINITION
AOCS
Average Occupied Cool Set Point
AOHS
Average Occupied Heat Set Point
AOZT
Average Occupied Zone Temperature
AUCS
Average Unoccupied Cool Set Point
AUHS
Average Unoccupied Heat Set Point
AZT
Average Zone Temperature
NEXTOCCD
Next Occupied Day
NEXTOCCT
Next Occupied Time
NEXTUNOD
Next Unoccupied Day
NEXTUNOT
Next Unoccupied Time
OCCSTAT
Occupancy Status
PREVUNOD
Previous Unoccupied Day
PREVUNOT
Previous Unoccupied Time
ENTER
