Carrier WEATHERMAKER 48/50AJ - Manual (Page 31)

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THIRD PARTY CONTROL
Thermostat — The method of control would be through
the thermostat inputs:
Y1 = first stage cooling
Y1 and Y2 = first and second stage cooling
W1 = first stage heating
W1 and W2 = first and second stage heating
G = supply fan
Alarm Output — The alarm output TB4-7 and 8, will pro-
vide relay closure whenever the unit is under an alert or alarm
condition.
Remote Switch — The remote switch may be configured
for three different functions. Under Configuration  UNIT, set
RM.CF to one of the following:
0 = no remote switch
1 = occupied/unoccupied switch
2 = start/stop switch
3 = occupancy override switch
With RM.CF set to 1, no time schedules are followed and
the unit follows the remote switch only in determining the state
of occupancy.
With RM.CF set to 2, the remote switch can be used to shut
down and disable the unit, while still honoring time guards on
compressors. Time schedules, internal or external, may be run
simultaneously with this configuration.
With RM.CF set to 3, the remote input may override an
unoccupied state and force the control to go into occupied
mode. As with the start/stop configuration, an internal or exter-
nal time schedule may continue to control occupancy when the
switch is not in effect.
Under Configuration  SW.LG  RMI.L, the remote occu-
pancy switch can be set to either a normally open or normally
closed switch input. Normal is defined as either unoccupied, start
or “not currently overridden,” respective to the RM.CF
configuration.
VFD Control — On VFD equipped supply fans, supply
duct static pressure control may be left under unit control or be
externally controlled. To control a VFD externally with a 4 to
20 mA signal, set SP.RS to 4, under the Configuration  SP
menu. This will set the reset to VFD control. When SP.RS = 4,
the static pressure reset function acts to provide direct VFD
speed control where 4 mA = 0% speed and 20 mA = 100%
(SP.MN and SP.MX will override). Note that SP.CF must be
set to 1 (VFD Control) prior to configuring SP.RS = 4. Failure
to do so could result in damage to ductwork due to overpressur-
ization. In effect, this represents a speed control signal “pass
through” under normal operating circumstances. The Com-
fortLink controller overrides the third party signal for critical
operation situations, most notably smoke and fire control. Wire
the input to the controls expansion module (CEM) using TB-11
and 12. An optional CEM board is required.
See Appendix C and the VFD literature supplied with the unit
for VFD configurations and field wiring connections to the VFD.
Supply Air Reset — With the installation of the CEM,
the ComfortLink controller is capable of accepting a 4 to
20 mA signal, to reset the supply-air temperature up to a maxi-
mum of 20 F. See VFD Control section above.
Demand Limit Control — The term “demand limit
control” refers to the restriction of the machine’s mechanical
cooling capacity to control the amount of power that a machine
may use.
Demand limiting using mechanical control is possible via two
means:
Two discrete inputs tied to demand limit set point percentages.
OR
A 4 to 20 mA input that can reduce or limit capacity linearly to
a set point percentage.
In either case, it will be necessary to install a controls ex-
pansion module (CEM).
DEMAND LIMIT DISCRETE INPUTS — First, set DM.L.S
in Configuration  DMD.L to 1 (2 switches).
When Inputs  GEN.I  DL.S1 (Demand Switch no. 1) is
OFF, the control will not set any limit to the capacity, and
when ON, the control sets a capacity limit to the Configura-
tion  DMD.L  D.L.S1 set point.
Likewise, when Inputs  GEN.I  DL.S2 (Demand Switch
no. 2) is OFF, the control will not set any limit to the capacity,
and when ON, the control sets a capacity limit to the Configu-
ration  DMD.L  D.L.S2 set point.
If both switches are ON, Inputs  GEN.I  DL.S2 is used
as the limiter of capacity.
Under Configuration  SW.LG, set the logic state appropri-
ately for the action desired. Set the DL1.L and DL2.L configu-
rations. They can be set normally open or normally closed. For
example, if DL1.L is set to OPEN, the user will need to close
the switch to cause the control to limit capacity to the demand
limit 1 set point. Likewise, if DL1.L is set to CLSE (closed),
the user will need to open the switch to cause the control to
limit capacity to the demand limit 1 set point.
DEMAND LIMIT 4 TO 20 mA INPUT — Under Configu-
ration  DMD.L, set configuration DM.L.S to 2 (2 = 4 to
20 mA control). Under the same menu, set D.L.20 to a value
from 0 to 100% to set the demand limit range. For example,
with D.L.20 set to 50, a 4 mA signal will result in no limit to
the capacity and 20 mA signal will result in a 50% reduction in
capacity.
Demand Controlled Ventilation Control —
There are multiple methods for externally controlling the econ-
omizer damper.
IAQ DISCRETE INPUT CONFIGURATION — The IAQ dis-
crete input configuration requires a CEM module (optional) to
be installed and an interface to a switch input at TB5-13 and
14. The state of the input on the display can be found at
Inputs  AIR.Q  IAQ.I.
Before configuring the switch functionality, first determine
how the switch will be read. A closed switch can indicate either
a low IAQ condition or a high IAQ condition. This is set at
Configuration  SW.LG and IAQ.L. The user can set what a
low reading would mean based on the type of switch being
used. Setting IAQ.L to OPEN means that when the switch is
open the input will read LOW. When the switch is closed, the
input will read HIGH. Setting IAQ.L to CLSE (closed) means
that when the switch is closed the input will read LOW, and
therefore, when the switch is open the switch will read HIGH.
There are two possible configurations for the IAQ discrete
input. Select item Configuration  IAQ  AQ.CF  IQ.I.C
and configure for either 1 (IAQ Discrete) or 2 (IAQ Discrete
Override).
IQ.I.C = 1 (IAQ Discrete) — If the user sets IQ.I.C to 1 (IAQ
Discrete), and the switch logic (Configuration  SW.LG 
IAQ.L) is set to OPEN, then an open switch reads low and a
closed switch reads high.
If the switch is open, the economizer will be commanded to
the IAQ Demand Vent Minimum Position.
These settings may be adjusted and are located at Configura-
tion  IAQ  DCV.C  IAQ.M.
If the switch is closed, the IAQ reading will be high and the
economizer will be commanded to the Economizer Minimum
Position.
This setting may be adjusted and is located at Configura-
tion  IAQ  DCV.C  EC.MN.