Special Ventilation Group; Indoor Air Quality (Iaq) - Carrier 48FP Controls Operation And Troubleshooting

Special Ventilation Group —
door Air Quality (IAQ), IAQ (Pre-Occupancy) Purge, Outdoor
Air CFM Control (OAC), and IAQ/OAC Reheat.
INDOOR AIR QUALITY (IAQ) — Indoor
function will admit fresh air into the space whenever space air
quality sensors detect unsuitable space conditions. Fresh air is
admitted by overriding the Economizer Minimum Damper po-
sition. The IAQ mode is permitted only during Occupied peri-
ods. See Table 25.
When IAQ is active, Mode 42 will be displayed (sizes 088-
104 only). When OAC is active, Mode 42 will be displayed
(sizes 088-104 only).
The IAQ mode also permits and controls analog-type reheat
system (hydronic or a modulating control electric heater).
Priority for IAQ can be selected by user. The IAQ mode can
be selected to override the economizer damper position at any
time that IAQ mode is active (and IAQ requires a more open
economizer position to satisfy the space air quality criteria).
The IAQ mode can also be configured so that it will only dic-
tate economizer position when no space heating or cooling
mode is active (active comfort mode will dictate position for
economizer outdoor air dampers) and/or be overridden by
Comfort Overrides.
Occupied Cooling (including Economizer Cooling) and Oc-
cupied Heating are permitted during IAQ and will function
normally (except when IAQ mode priority is HIGH; then ac-
tive IAQ mode may dictate a more open economizer position).
An IAQ sensor (field-supplied and installed), factory-
installed economizer option, and control options module
(available as a factory-installed option or field-installed acces-
sory on size 034-074 units and is standard on 078-104 units)
are required.
NOTE: The unit control is factory-configured for IAQ sensors
with a 0 to 10 vdc signal representing an air quality of 0 to
2000 ppm. Sensors with other characteristic curves will require
user reconfiguration (see Step 5 of configuration instructions
below).
Sequence of Operation
1. If the supply fan is off, the outside air dampers will be
closed.
2. The IAQ is available when the VENT Option is 1 or 3,
the unit is in Occupied mode, IAQ Priority Level is 1
(High) or 2 (Medium), and supply fan is on.
3. The Master Loop will evaluate the IAQ set point and
IAQ sensor value, then calculate IAQ Minimum
Damper Position (IMP).
4. If the IAQ Priority Level is 1 (High), the economizer
Submaster Loop will determine economizer damper
position based on the higher of calculated IAQ mini-
mum damper position or Minimum Damper Position
(Minimum Damper Position determined by econo-
mizer mode or active comfort modes).
5. If the IAQ Priority Level is 2 (Medium) and Cooling
(including Economizer Cooling) or Heating mode is
active, then the Economizer Submaster Loop will
determine Minimum Damper Position and the econo-
mizer will close to Minimum Damper Position (MDP).
Comfort Overrides:
VAV: If (SAT < SASP – 8 F) or (SAT > SASP + 5 F)
for 4 minutes, then IMP = 0 and economizer will close
to MDP.
CV: If (SPT > (OCSP + SPHO)/2) or (SPT < (OHSP +
SPLO)/2), then IMP = 0 and economizer will close to
MDP.
Once CV Space Temp Override has been initiated, it
will remain in effect until SPT ≤ OCSP and SPT ≥
OHSP.
This group includes In-
Air Quality
25
High Humidity:
If unit is equipped with humidity sensors and RH >
HHL, the IMP = 0 and economizer will close to MDP.
The Economizer Submaster Loop will determine econ-
omizer damper position (IQMP) based on higher of
IMP or MDP.
6. If IAQ not required, then the unit control sets IMP at 0.
The economizer remains at MDP position.
7. If IAQ is Priority 3 (low) and an IAQ sensor is con-
nected, the control will evaluate IAQ sensor value. If
the IAQ sensor value exceeds the user-configured alert
limits, an alert will be generated (viewed at the HSIO),
and broadcast to the CCN ComfortWORKS® software
(if applicable). The economizer damper position is not
affected.
Table 25 — Indoor-Air Quality Definitions
ITEM
CV Constant Volume
HHL High Humidity Limit
IAQ Indoor-Air Quality
IAQG IAQ Gain
IAQP IAQ Priority
IAQS IAQ Set Point
IMP IAQ Minimum Damper Position
IAQ Final Minimum Damper Position
IQMP
IQMX IAQ Maximum Damper Position
IRH IAQ Sensor High Reference
IRL IAQ Sensor Low Reference
IVH IAQ Sensor High Voltage Point
IVL IAQ Sensor Low Voltage Point
LEVEL IAQ Priority Level (088-104 only)
MDP Economizer Minimum Damper Position
OCSP Occupied Cooling Set Point
OHSP Occupied Heating Set Point
PRTY IAQ Priority Level (034-078 Only)
RH Relative Humidity
SASP Supply-Air Set Point
SAT Supply-Air Temperature
SPHO Space Temperature High Alert Limit (Occupied)
SPLO Space Temperature Low Alert Limit (Occupied)
SPT Space Temperature
VAV Variable Air Volume
VENT Ventilation Mode Configuration
Configuration — See Table 26. To configure:
1. Enable IAQ by selecting vent option. Press
enter the subfunction. Scroll down to VENT. A VENT
value of 1 indicates algorithm will use MDP and IAQ
modes. A value of 3 indicates algorithm will use MDP,
IAQ, and Outdoor Air Control (OAC) modes. A 0
indicates the algorithm will only use MDP mode.
2. Select IAQ Priority. Press
function. Scroll down to LEVEL (088-104 only). A
LEVEL value of 1 indicates High (IAQ mode has pri-
ority over active comfort modes). A value of 2 indi-
cates Medium (Active comfort mode or Comfort
Overrides may determine economizer damper posi-
tion, IAQ position overridden).
3. Select IAQ Set Point. Press
subfunction. Scroll down to IAQS. Enter the new
value. The default is 650 ppm. The range is 1 to
5000 ppm.
DEFINITION
to
to enter the sub-
to enter the