Specifications

26
4. Specify IAQ Maximum Damper Position. Press
to enter the subfunction. Scroll down to
IQMX. Enter the new value. The default is 50%. The
range is 0 to 100%.
5. If non-Carrier sensor used (see Fig. 13):
a. Specify IAQ sensor curve. Press to enter
the subfunction.
b. Configure Low Voltage Point. Scroll down to IVL.
Default is 0 v. Range is 0 to 10 v.
c. Configure Low Reference. Scroll down to IRL.
Default is 0 ppm. Range is 0 to 5000 ppm.
d. Configure High Voltage Point. Scroll down to IVH.
Default is 10 v. Range is 0 to 10 v.
e. Configure High Reference. Scroll down to IRH.
Default is 2000 ppm. Range is 0 to 5000 ppm.
IAQ Algorithms
IMP = ECON + 100 x IAQG x (Demand)/IAQS
Where: ECON = Current position of economizer damper
(Demand) = IAQS – IAQ
NOTE: IMP will not be recalculated until (Demand) exceeds
3% of IAQS.
IAQ (Pre-Occupancy) PURGE — If outdoor air conditions
permit, IAQ Pre-Occupancy Purge will open economizer and
energize supply fan 2 hours before next Occupied period, to
provide complete exchange of indoor air with fresh air. Dura-
tion of purge mode is user-configured (typically 5 minutes).
The IAQ Purge is Mode 28. See Table 27. The factory-
installed economizer option is required.
Sequence of Operation
— The IAQ Purge will operate only if
the following conditions exist:
• Economizer installed and enabled.
• Current Time and next Occupied Time are valid.
• Purge option is enabled.
• Unit is in Unoccupied state.
• Time is within 2 hours of next Occupied period.
• Time is within Purge Duration.
• Outdoor-Air Temperature reading is available.
If all the conditions above are satisfied, then IAQ Pre-
Occupancy Purge is enabled. The supply fan and Heat Inter-
lock Relays are energized. The economizer minimum position
is set to PURGEMP. The economizer opens to PURGEMP.
The purge continues until Purge Duration expires or Occupied
period begins.
NOTE: IAQ Purge is limited to one per Unoccupied period. If
PURGEMP = 0% then IAQ Purge is not enabled.
The control determines PURGEMP in the following manner:
NTLO OCSP
OAT <-------------|-----------------------------|--------------->Incr
Table 27 — Indoor-Air Quality Purge Definitions
Table 26 — Configuring Indoor Air Quality (IAQ)
PURGEMP
= LTMP
If Enthalpy Good:
PURGEMP
= HTMP
PURGEMP - 100%
-----------------------------
If Enthalpy
Not Acceptable:
PURGE MP = HTMP
ITEM DEFINITION
ENTH
Enthalpy
HTMP
High Temperature Minimum Position
IAQPG
IAQ Pre-Occupancy Purge Mode
IQPD
Purge Duration
LTMP
Low Temperature Minimum Position
NTLO
Nighttime Lockout Temperature
OAT
Outdoor-Air Temperature
OCSP
Occupied Cooling Set Point
PURG
Purge Option
PURGEMP
Purge Minimum Damper Position
DESCRIPTION HOW TO CONFIGURE AT HISO SET POINT RANGE
Enable by selecting VENT option
VENT
1 = Use IAQ only
3 = Use IAQ and OAC
Select IAQ Priority
LEVEL
1 = High
2 = Medium (Space Comfort Overrides)
3 = Low (Alert only)
Select IAQ Set Point
IAQS 1 to 5000 ppm
Specify IAQ Max Damper Position
IQMX 0 to 100%
LEGEND
NOTE: Voltage range is 0 to 10.
Fig. 13 — Sensor Use Example
IAQ —
Indoor Air Quality
IAQS —
IAQ Set Point
IRH —
IAQ Sensor High Reference
IRL —
IAQ Sensor Low Reference
IVH —
IAQ Sensor High Voltage Point
IVL —
IAQ Sensor Low Voltage Point