27
NOTE: If
D.F.ON
is configured below
DAQ.H
, the unit is in
occupied mode, and the fan was off, then DAQ rose above
D.F.ON
and the fan came on, the economizer will go to the
economizer minimum position (
EC.MN
).
The 4 to 20 mA signal from the sensor wired to TB5-6 and
7 is scaled to an equivalent indoor CO
2
(IAQ) by the parame-
ters
IQ.R.L
and
IQ.R.H
located under the
Configuration
IAQ
AQ.S.R
menu. The parameters are defined such that
4 mA =
IQ.R.L
and 20 mA =
IQ.R.H
. When the differential air
quality DAQ (IAQ –
OAQ.U
) exceeds the
DAQ.H
setpoint
(
Configuration
IAQ
AQ.SP
menu) and the supply fan is
on, the economizer minimum vent position (
Configuration
IAQ
DCV.C
EC.MN
) is overridden and the damper is
moved to the
IQ.P.O
configuration. When the DAQ falls below
the
DAQ.L
setpoint (
Configuration
IAQ
AQ.SP
menu),
the economizer damper is moved back to the minimum vent
position (
EC.MN
).
NOTE: Configuration
OAQ.U
is used in the calculation of the
trip point for override and can be found under
Configura-
tion
IAQ
AQ.SP
.
IQ.A.C
= 3
(4 to 20 mA Damper Control) — This configura-
tion will provide full 4 to 20 mA remotely controlled analog in-
put for economizer minimum damper position. The 4 to 20 mA
signal is connected to terminals TB5-6 and 7. The input is
processed as 4 mA = 0% and 20 mA = 100%, thereby giving
complete range control of the effective minimum position.
The economizer sequences can be disabled by setting
Con-
figuration
ECON
E.SEL
to 0.
Complete control of the
economizer damper position is then possible by using a 4 to
20 mA economizer minimum position control or a 0 to
10,000 ohms 0 to 100% economizer minimum position control
via configuration decisions at
Configuration
IAQ
AQ.CF
IQ.A.C
.
IQ.A.C
= 4
(10 Kilo-ohm Potentiometer Damper Control)
— This configuration will provide input for a 10 kilo-ohm lin-
ear potentiometer that acts as a remotely controlled analog in-
put for economizer minimum damper position. The input is
processed as 0 ohms = 0% and 10,000 ohms = 100%, thereby
giving complete range control of the effective minimum
position.
CONTROLS OPERATION
Modes —
The
Comfort
Link controls operate under a hierar-
chy of command structure as defined by three essential ele-
ments: the System mode, the HVAC mode and the Control
mode. The System mode is the top level mode that defines three
essential states for the control system: OFF, RUN, and TEST.
The HVAC mode is the functional level underneath the
System mode which further defines the operation of the
control. The mode selection process is shown in Appendix D.
The Control mode is essentially the control type of the unit
(
Configuration
UNIT
C.TYP
). This defines from where
the control looks to establish a cooling or heating mode and
whether 2 stages or multiple stages of cooling capacity opera-
tion are controlled.
Furthermore, there are a number of modes which operate
concurrently when the unit is running. The operating modes of
the control are located at the local displays under
Operating
Modes
.
See Table 31.
Currently Occupied (
OCC
) — This variable displays the
cur-
rent occupied state of the unit.
Timed Override in Effect (
T.OVR
) — This variable displays
if the state of occupancy is currently occupied due to an
override.
DCV Resetting Minimum Position (
DCV
) — This variable
displays if the economizer position has been lowered from its
maximum vent position.
Table 31 — Operating Modes Display Table
Supply Air Reset (
SA.R
) — This variable displays if the sup-
ply air reset is currently active. This applies to cooling only.
Demand Limit in Effect (
DMD.L
) — This variable displays
if the mechanical cooling capacity is currently being limited or
reduced by an outside third party.
Temperature Compensated Start (
T.C.ST
) — This variable
displays if Heating or Cooling has been initiated before the
occupied period to pre-condition the space.
IAQ Pre-Occupancy Purge Active (
IAQ.P
) — This variable
displays if the economizer is open and the fan is on to pre-
ventilate the building before occupancy.
Linkage Active CCN (
LINK
) — This variable displays if a
linkage master in a zoning system has established “linkage”
with this air source (rooftop).
Mechanical Cooling Locked Out (
LOCK
) — This variable
displays if mechanical cooling is currently being locked due to
low outside air temperature.
HVAC Mode Numerical Form (
H.NUM
) — This is a numer-
ical representation of the HVAC modes which may be read via
a point read.
SYSTEM MODES (
Operating Modes
SYS.M
)
System Mode Off — When the system mode is OFF, all out-
puts are to be shut down and no machine control is possible.
The following list displays the text assigned to the System
Mode when in the OFF mode and the conditions that may
cause this mode are checked in the following hierarchal order:
1. Wake up timer on a power reset.
(“Initializing System ...”)
2. System in the process of shutting down compressors and
waiting for timeguards to expire.
(“Shutting Down ...”)
3. Factory shut down (internal factory control level —
SHUTDOWN).
(“Factory Shut Down”)
4. Unit stop (software application level variable that acts as
a hard shut down —
Service Test
STOP
).
(“Local Machine Stop”)
5. Fire shut down (traumatic fire shutdown condition based
on the Fire Shutdown Input —
Inputs
FIRE
FSD
).
(“Fire-Shutdown Mode”)
6. Emergency stop, which is forced over the CCN through
the Emergency Stop Variable (EMSTOP).
(“CCN Emergency Stop”)
7. Startup delay.
(“Startup delay = 0-900 secs”)
8. Service test ending transition timer.
(“Service Test Ending”)
9. Unexplained internal software failure.
(“Internal Failure”)
ITEM
EXPANSION
RANGE
CCN POINT
SYS.M
ascii string
n/a
HVAC
ascii string
n/a
CTRL
ascii string
n/a
MODE
MODES CONTROLLING UNIT
OCC
Currently Occupied
ON/OFF MODEOCCP
T.OVR
Timed Override in Effect
ON/OFF MODETOVR
DCV
DCV Resetting Min Pos
ON/OFF MODEADCV
SA.R
Supply Air Reset
ON/OFF MODESARS
DMD.L
Demand Limit in Effect
ON/OFF MODEDMLT
T.C.ST
Temp.Compensated Start
ON/OFF MODETCST
IAQ.P
IAQ Pre-Occ Purge Active
ON/OFF MODEIQPG
LINK
Linkage Active — CCN
ON/OFF MODELINK
LOCK
Mech.Cooling Locked Out
ON/OFF MODELOCK
H.NUM
HVAC Mode Numerical Form
number
MODEHVAC
Summary of Contents for Carrier Weathermaker 48A2
Page 105: ...105 Fig 20 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units...
Page 106: ...106 Fig 21 Typical Auxiliary Control Box Wiring Schematic...
Page 107: ...107 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown a48 8357...
Page 108: ...108 TO NEXT PAGE Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown A48 7296...
Page 109: ...109 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont A48 8358...
Page 110: ...110 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown a50 8228...
Page 111: ...111 Fig 25 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown...
Page 112: ...112 Fig 26 Typical Low Ambient Controls Option Wiring...
Page 113: ...113 Fig 27 Typical Small Chassis Component Location Size 020 035 Units...
Page 114: ...114 Fig 28 Typical Large Chassis Component Locations Size 040 060 Units...
Page 118: ...118 Fig 30 Economizer Control Board ECB1 and VAV Control Board ECB2 A48 7706...
Page 142: ...142 A48 3733 Fig 56 Main Burner Removal...
Page 176: ...176 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716...
