United Technologies Carrier Weathermaker 48A2, Controls, Start-Up, Operation, Service, And Troubleshooting

Page: 26 / 208

26
Demand limiting using mechanical control is possible via two
means:
1. Two discrete inputs tied to demand limit setpoint percent-
ages.
2. A 4 to 20 mA input that can reduce or limit capacity lin-
early to a setpoint 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 setpoint.
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 setpoint.
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 setpoint. 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 setpoint.
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 .
IQ.I.C = 2 (IAQ Discrete Override) — If the user sets IQ.I.C
to 2 (IAQ Discrete Override), and Configuration

SW.LG

IAQ.L is set to OPEN, then an open switch reads low and a
closed switch reads high.
If the switch reads low, no action will be taken. If the switch
reads high, the economizer will immediately be commanded to
the IAQ Economizer Override Position. This can be set from 0
to 100% and can be found at Configuration

IAQ

AQ.SP

IQ.O.P .
FAN CONTROL FOR THE IAQ DISCRETE INPUT —
Under Configuration

IAQ

AQ.CF , the IQ.I.F (IAQ Dis-
crete Input Fan Configuration) must also be set. There are
three configurations for IQ.I.F . Select the configuration which
will be used for fan operation. This configuration allows the
user to decide (if the supply fan is not already running),
whether the IAQ discrete switch will start the fan, and in which
state of occupancy the fan will start.
IAQ ANALOG INPUT CONFIGURATION — This input is
an analog input located on the main base board (MBB). There
are 4 different functions for this input. The location of this con-
figuration is at Configuration

IAQ

AQ.CF

IQ.A.C .
The functions possible for IQ.A.C are:
• 0 = no IAQ analog input
• 1 = IAQ analog input
• 2 = IAQ analog input used to override to a set position
• 3 = 4 to 20 mA 0 to 100% economizer minimum position
control
• 4 = 0 to 10,000 ohms 0 to 100% economizer minimum
position control
Options 2, 3, and 4 are dedicated for third party control.
IQ.A.C = 2 (IAQ Analog Input Used to Override) — Under
Configuration

IAQ

AQ.SP , set IQ.O.P (IAQ Economizer
Override Position). The IQ.O.P configuration is adjustable
from 0 to 100%. These configurations are also used in conjunc-
tion with Configuration

IAQ

AQ.CF

IQ.A.F (IAQ 4 to
20 mA Fan Configuration). There are three configurations for
IQ.A.F and they follow the same logic as for the discrete input.
This configuration allows the user to decide (if the supply fan is
not already running), if the IAQ Analog Minimum Position
Override input will start the fan, and in which state of occupan-
cy the fan will start.
If IQ.A.F is configured to request the supply fan, then
configurations D.F.ON and D.F.OF need to be set. These
configuration settings are located under Configuration

IAQ

AQ.SP and configure the fan override operation based
on the differential air quality (DAQ). If DAQ rises above
D.F.ON , the control will request the fan on until DAQ falls
below D.F.OF .
IQ.I.F = 0 Minimum Position Override Switch input
will not start fan
IQ.I.F = 1 Minimum Position Override Switch input
will start fan in occupied mode only
IQ.I.F = 2 Minimum Position Override Switch input
will start fan in both occupied and unoccu-
pied modes
IQ.A.F = 0 IAQ analog sensor input cannot start the
supply fan
IQ.A.F = 1 IAQ analog sensor input can start the supply
fan in occupied mode only
IQ.A.F = 2 IAQ analog sensor input can start the supply
fan in both occupied and unoccupied modes