32
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 be-
low D.F.OF.
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.SR 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 set point
(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 set point (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 kilo-ohm 0 to 100% economizer minimum position control
via configuration decisions at Configuration
→
IAQ
→
IQ.A.C.
IQ.A.C
= 4 (10 Kilo-ohm Potentiometer Damper Control)
— This configuration will provide input for a 10 kilo-ohm
linear potentiometer that acts as a remotely controlled analog
input 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 ComfortLink™ controls operate under a
hierarchy of command structure as defined by three essential
elements: 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 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 42.
Table 42 — Operating Modes Display Table
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.
Supply Air Reset (
SA.R) — This variable displays if the sup-
ply air set point that the rooftop is attempting to maintain is
currently being reset upwards. 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 ...”)
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
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
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