27
Table 28 — Configuring IAQ (Pre-Occupancy) Purge
Configuration
— See Table 28. To configure:
1. Enable Purge option. Press to enter the sub-
function. Scroll down to PURG. Set to 1 to Enable.
(Set to 0 to disable.)
NOTE: The following user-configured options require
use of Service Tool or CCN ComfortWORKS
soft-
ware to change.
2. Select Purge Duration period. Change IQPD set point.
Default is 5 minutes. Range is 5 to 60 minutes.
3. Select Low Temperature Minimum Position. Change
LTMP set point. Default is 10%. Range is 0 to 100%.
4. Select High Temperature Minimum Position. Change
HTMP set point. Default is 35%. Range is 0 to 100%.
Table 29 — Outdoor Air Control Definitions
OUTDOOR AIR CONTROL (OAC) — The Outdoor Air
Control function will maintain a minimum quantity of outdoor
airflow into an occupied space, regardless of space comfort
load conditions. The OAC is permitted only during Occupied
periods. Occupied Cooling (including Economizer Cooling)
and Occupied Heating are permitted during OAC and will
function normally, except when OAC mode is active, then
OAC mode may dictate a more open economizer position. See
Table 29. The factory-installed economizer option and control
options module (available as a factory-installed option or field-
installed accessory on size 034-074 units and is standard on
078-104 units) are required.
An OAC Accessory package (consists of velocity sensor
and pressure transducer) (P/N 50DJ-900---791) is required.
Sequence of Operation
— OAC is available when the VENT
Option is 2 or 3, unit is in Occupied status, and supply fan is
on. The control will calculate a Minimum Damper Position
based on the Outside Air CFM set point and the Outside Air
CFM (current delivered value).
The current delivered CFM value (OAC) is determined by
interpolating from a unit-size-specific table relating airflow
rate to voltage drop at the outdoor cfm velocity sensor, via
pressure transducer in the outdoor cfm accessory package. The
actual damper position (IQMP) will be determined by highest
value demanded by available functions (OAC function, IAQ
function, Minimum Economizer Damper position, or active
comfort mode). The output signal from the economizer Sub-
master Loop to the economizer damper actuator drives the
damper to the desired position. If the economizer position has
been dictated by another function but this controlling function
is driving economizer closed, economizer position will not be
permitted to move to a value below the OAC control required
position.
Configuration
— See Table 30. To configure the function:
1. Enable the OAC function. Press to enter the
subfunction. Scroll down to VENT. Enable the func-
tion by pressing or and . A 2 configures
the function for Minimum Damper Position and OAC
control only. A 3 configures the function for Minimum
Damper Position, IAQ, and OAC control.
2. Select the OAC set point. Press and to
enter the subfunction. Scroll down to OCS. The default
is 1 cfm. The range is 1 to 50,000 cfm.
3. Select the OAC Maximum Damper Position. Press
to enter the subfunction. Scroll down to
OCMX. The default is 50%. The range is 0 to 100%.
Algorithms
OAC Minimum Position = ECON + 100 x OACG x
(Demand term)/OCS
where: (Demand term) = OCS – OAC
IAQ/OAC REHEAT — When the IAQ/OAC routine has pri-
ority over comfort conditions, it is possible to introduce outside
air at temperatures well below typical space temperatures. The
IAQ/OAC Reheat function will modulate a unit- or duct-
mounted steam or hydronic heating coil (equipped with modu-
lating control valve) via a 4 to 20 mA control signal to raise
supply-air temperature of outside air delivered to ductwork.
See Table 31.
A heating coil (field-supplied/installed) with control valve
connected to Ch. 43 and a supply air sensor located down-
stream of heating coil (will require relocation of sensor if coil is
mounted in duct) are required.
Table 30 — Configuring Outdoor Air CFM Control (OAC)
DESCRIPTION HOW TO CONFIGURE AT HSIO SET POINT RANGE
Enable Purge
PURG Enable = 1; Disable = 0
ITEM DEFINITION
ECON
Economizer Position
IAQ
Indoor-Air Quality Function
IQMP
Final Minimum Damper Position
OAC
Outdoor-Air Control CFM
OAC
Outdoor-Air Control Function
OACG
Outdoor-Air Control Gain
OCS
Outdoor-Air Control Set Point
OCMX
OAC Maximum Damper Position
VENT
Ventilation Mode Configuration
ENTER
DESCRIPTION HOW TO CONFIGURE AT HSIO SET POINT RANGE
Enable OAC Function (select VENT option)
VENT
2 = Use OAC only
3 = Use IAQ and OAC
Select OAC Set Point
OCS
1 to 50,000 CFM
(1 to 23596 L/s)
Select OAC Max Damper Position
OCMX 0 to 100
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