IAQ Econo Override Pos (Configuration→IAQ→AQ.SP→ IQ.O.P) — This configuration is the position that the econo- mizer goes to when override is in effect.
Diff. Air Quality Lo Limit (Configuration→IAQ→ AQ.SP →DAQ.L) — This is the differential CO2 level at which IAQ control of the dampers will be initiated.
Diff. Air Quality Hi Limit (Configuration→IAQ→ AQ.SP →DAQ.H) — This is the differential CO2 level at which IAQ control of the dampers will be at maximum and the dampers will be at the Configuration→ IAQ→DCV.C→EC.MN.
DAQ ppm Fan Off Set Point (Configuration→IAQ →AQ.SP→D.F.OF) — This is the CO2 level at which the indoor fan will be turned off.
DAQ ppm Fan On Set Point (Configuration →IAQ→AQ.SP→D.F.ON) — This is the CO2 level at which the indoor fan will be turned on.
Diff. IAQ Responsiveness (Configuration→IAQ→AQ.SP →IAQ.R) — This is the configuration that is used to select the IAQ response curves as shown in Fig. 13.
OAQ Lockout Value (Configuration→IAQ→AQ.SP→ OAQ.L) — This is the maximum OAQ level above which de- mand ventilation will be disabled.
User Determined OAQ (Configuration→IAQ→AQ.SP→ OAQ.U) — If an OAQ sensor is unavailable, the user can manually set the OAQ reading.
IAQ Low Reference (Configuration→IAQ→AQ.S.R→ IQ.R.L) — This is the reference that will be used with a
IAQ High Reference (Configuration→IAQ→AQ.S.R →IQ.R.H) — This is the reference that will be used with a
OAQ Low Reference (Configuration→IAQ→AQ.S.R →OQ.R.L) — This is the reference that will be used with a
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 represents the CO2 level at 20 mA.
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 available 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 are true then the dampers will be positioned 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
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 po- sition 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 Dehumidifi- cation function will override comfort condition set points based on dry bulb temperature and deliver cooler air to the space in order to satisfy a humidity set point at the space or return air humidity sensor. The Reheat function will energize a suitable heating system concurrent with dehumidification sequence should the dehumidification operation result in excessive cooling of the space condition.
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 accomodate an RH switch. Reheat is possible when
Dehumidification and reheat control are allowed during Cooling and Vent modes in the Occupied period.
On constant volume units using thermostat inputs (C.TYP = 3 or 4), the discrete switch input must be used as the dehumidi- fication control input. The commercial Thermidistat™ device is the recommended accessory device.
SETTING UP THE SYSTEM — The settings for dehumidi- fication can be found at the local display at Configuration→ DEHU. See Table 85.
Dehumidification Configuration (D.SEL) — The dehumidi- fication configuration can be set for the following settings:
•D.SEL = 0 — No dehumidification and reheat.
•D.SEL = 1 — The control will perform dehumidification and reheat with staged gas only.
•D.SEL = 2 — The control will perform both dehumidifi- cation 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 reheat. A typical application might be to energize a
Dehumidification Sensor (D.SEN) — The sensor can be con- figured 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 Dehu- midification mode.
•D.EC.D = YES — Economizer disabled during dehu- midification (default).
•D.EC.D = NO — Economizer not disabled during dehu- midification.
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