73
IAQ Low Reference (Configuration
IAQ
AQ.S.R
IQ.R.L)
This is the reference that will be used with a non-Carrier IAQ
sensor that may have a different characteristic curve. It rep-
resents the CO
2
level at 4 mA.
IAQ High Reference (Configuration
IAQ
AQ.S.R
IQ.R.H)
This is the reference that will be used with a non-Carrier IAQ
sensor that may have a different characteristic curve. It rep-
resents the CO
2
level at 20 mA.
OAQ Low Reference (Configuration
IAQ
AQ.S.R
OQ.R.L)
This is the reference that will be used with a non-Carrier OAQ
sensor that may have a different characteristic curve. It rep-
resents the CO
2
level at 4 mA.
OAQ High Reference (Configuration
IAQ
AQ.S.R
OQ.R.H)
This is the reference that will be used with a non-Carrier OAQ
sensor that may have a different characteristic curve. It rep-
resents the CO
2
level at 20 mA.
PRE-OCCUPANCY PURGE
The control has the option for a pre-occupancy purge to refresh
the air in the space prior to occupancy.
This feature is enabled by setting Configuration
IAQ
IAQ.P
IQ.PG to Yes.
The IAQ purge will operate under the following conditions:
• IQ.PG is enabled
• the unit is in the unoccupied state
• Current Time is valid
• Next Occupied Time is valid
• time is within two hours of the next occupied period
• time is within the purge duration (Configuration
IAQ
IAQ.P
IQ.P.T)
If all of the above conditions are met, the following logic is used:
If OAT IQ.L.O and OAT OCSP and economizer is avail-
able then purge will be enabled and the economizer will be
commanded to 100%.
If OAT < IQ.L.O then the economizer will be positioned to the
IAQ Purge LO Temp Min Pos (Configuration
IAQ
IAQ.P
IQ.P.L)
If neither of the above is true then the dampers will be posi-
tioned to the IAQ Purge HI Temp Min Pos (Configuration
IAQ
IAQ.P
IQ.P.H)
If this mode is enabled the indoor fan and heat interlock relay
(VAV) will be energized.
IAQ Purge (Configuration
IAQ
IAQ.P
IQ.PG)
This is used to enable IAQ pre-occupancy purge.
IAQ Purge Duration (Configuration
IAQ
IAQ.P
IQ.P.T)
This is the maximum amount of time that a purge can occur.
IAQ Purge Lo Temp Min Pos (Configuration
IAQ
IAQ.P
IQ.P.L)
This is used to configure a low limit for damper position to be
used during the purge mode.
IAQ Purge Hi Temp Min Pos (Configuration
IAQ
IAQ.P
IQ.P.H)
This is used to configure a maximum position for the dampers
to be used during the purge cycle.
IAQ Purge OAT Lockout Temp (Configuration
IAQ
IAQ.P
IQ.L.O)
Nighttime lockout temperature below which the purge cycle
will be disabled.
Dehumidification and Reheat
The Dehumidification function will override cooling staging
setpoint and deliver cooler air to the Fan Section in order to
satisfy a humidity setpoint at the space or return air humidity
sensor. The Reheat function will activate a suitable heating
system concurrent with dehumidification sequence should the
dehumidification operation result in excessive cooling at the
Evaporator Dewpoint sensor.
The dehumidification sequence requires the installation of a
space or return air humidity sensor or a discrete switch input.
An ECB option is required to accommodate an RH (relative
humidity) sensor connection. A CEM (option or accessory) is
required to accommodate an RH switch. Reheat is possible
when multiple-step staged gas control option or hydronic heat
field-installed coil is installed. Reheat is also possible using a
heat reclaim coil (field-supplied and installed) or a DX (direct
expansion) reheat coil. The alarm relay may also be used to en-
able an external reheat device.
Dehumidification and reheat control are allowed during Cool-
ing, Heating, and Vent modes in the Occupied period. Any RH
sensor or a switch may be used.
SETTING UP THE SYSTEM
The settings for dehumidification can be found at the local dis-
play at Configuration
DEHU. See Table 69.
Dehumidification Configuration (D.SEL)
The dehumidification configuration can be set for the follow-
ing settings:
• D.SEL = 0 – (NO DEHUMIDIFY) – No dehumidification
and reheat; this is the default.
• D.SEL = 1 – (DH - ST.GAS) – The control will perform
dehumidification and reheat with staged gas only.
• D.SEL = 2 – (DH - RELAY) – The control will perform both
dehumidification and reheat with third party heat via an alarm
relay. In the case of D.SEL=2, during dehumidification, the
alarm relay will close to convey the need for “re-heat.” A typ-
ical application might be to energize a 3-way valve to perform
DX reheat.
• D.SEL = 3 – (DH - HUMDZR) – The control will use the
Humidi-MiZer
®
adaptive dehumidification system. If the
system has Staged Gas Heat and Humidi-MiZer is select-
ed, then only when Dehumidification results in Heating
demand will Supplemental Staged Gas heat come on, until
the heating demand is satisfied.
Dehumidification Sensor (D.SEN)
The sensor can be configured for the following settings:
• D.SEN = 1 — Initiated by return air relative humidity sensor.
• D.SEN = 2 — Initiated by discrete input.
Economizer Disable in Dehum Mode (D.EC.D)
This configuration determines economizer operation during
Dehumidification mode. This configuration will have a range
of 1 to 2 with default of 1.
The RARH Sensor and discrete input utilized must be compat-
ible with the ComfortLINK hardware and software.
• D.EC.D = YES — Economizer disabled during dehumidi-
fication (default).
• D.EC.D = NO — Economizer not disabled during dehu-
midification.
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