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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 is 24-v at TB201-12 and TB201-11. The contact
will provide relay closure whenever the unit is under an alert or
alarm condition (5 va maximum).
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
Under Configuration
SW.LG
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.
With RM.CF set to 1, no time schedules are followed and the unit
follows the remote switch only in determining the state of occu-
pancy.
With RM.CF set to 2, the remote switch can be used to shut down
and disable the unit, while still honoring timeguards on compres-
sors. Time schedules, internal or external, may be run simultane-
ously with this configuration.
With RM.CF set to 3, the remote input may override an unoccu-
pied state and force the control to go occupied mode. As with the
start/stop configuration, an internal or external time schedule may
continue to control occupancy when the switch is not in effect.
VFD Control
On VFD equipped supply fans, supply duct static pressure control
may be left under unit control or be externally controlled. To con-
trol a VFD externally with a 4 to 20 mA signal, set SP.RS to 4, un-
der 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 over-
pressurization.
In effect, this represents a speed control signal "pass through" un-
der normal operating circumstances. The ComfortLink 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
TB202-6 and TB202-7. An optional CEM board is required.
See Appendix D 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 controls are
capable of accepting a 4 to 20 mA signal to reset the supply-air
temperature up to a maximum of 20°F.
Under Configuration
EDT.R, set RS.CF to 3 (external 4 to 20
mA supply air reset control). The 4 to 20 mA input to the control
system (TB202-9 and TB202-8), will be linearized and range from
RMI.L, the remote occupancy
0ºF to 20°F. For example, 4 mA = 0ºF reset, 12 mA = 10°F reset
and 20 mA = 20ºF reset.
Demand Limit Control
The term demand limit control refers to the restriction of the ma-
chine's mechanical cooling capacity to control the amount of pow-
er that a machine may use.
Demand limiting 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 CEM. The control in-
terfaces to a switch input at TB202-10 and TB202-11.
DEMAND LIMIT DISCRETE INPUTS
First, set DM.L.S in Configuration
When Inputs
GEN.I
the control will not set any limit to the capacity, and when ON,
the control sets a capacity limit to the Configuration
DMD.L
D.L.S1 set point.
Likewise, when Inputs
is OFF, the control will not set any limit to the capacity, and when
ON, the control sets a capacity limit to the Configuration
DMD.L
D.L.S2 set point.
If both switches are ON, Inputs
limiter of capacity.
Under Configuration
for the action desired. Set the DL1.L and DL2.L configurations.
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 de-
mand limit 1 set point.
DEMAND LIMIT 4 TO 20 mA INPUT
Under Configuration
= 4 to 20 mA control). Under the same menu, set D.L.20 to a val-
ue 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 capac-
ity and 20 mA signal will result in a 50% reduction in capacity.
Economizer/Outdoor Air Damper Control
There are multiple methods for externally controlling the econo-
mizer damper.
IAQ DISCRETE INPUT CONFIGURATION
The IAQ (indoor air quality) discrete input configuration requires
a CEM module (optional) to be installed and an interface to a
switch input at TB202-12 and TB202-13. The state of the input on
the display can be found at Inputs
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 Configura-
tion
SW.LG
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
ure for either 1 (IAQ Discrete) or 2 (IAQ Discrete Override).
42
DMD.L to 1 (2
DL.S1 (Demand Switch no. 1) is OFF,
GEN.I
DL.S2 (Demand Switch no. 2)
GEN.I
DL.S2 is used as the
SW.LG, set the logic state appropriately
DMD.L, set configuration DM.L.S to 2 (2
AIR.Q
IAQ.I.
IAQ
AQ.CF
IQ.I.C and config-
switches).
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Troubleshooting
