Carrier 48AJ Operating And Service Manual page 58

ITEM
EC.EN Economizer Installed?
EC.MN Economizer Min.Position
EC.MX Economizer Max.Position
E.TRM Economzr Trim For SumZ ?
E.SEL Econ ChangeOver Select
OA.E.C OA Enthalpy ChgOvr Selct
OA.EN Outdr.Enth Compare Value
OAT.L High OAT Lockout Temp
O.DEW OA Dewpoint Temp Limit
ORH.S Outside Air RH Sensor
E.TYP Economizer Control Type
E.SW Economizer Switch Config
E.CFG ECON.OPERATION CONFIGS
E.P.GN Economizer Prop.Gain
E.RNG Economizer Range Adjust
E.SPD Economizer Speed Adjust
E.DBD Economizer Deadband
UEFC UNOCC.ECON.FREE COOLING
FC.CF Unoc Econ Free Cool Cfg
FC.TM Unoc Econ Free Cool Time
FC.L.O Un.Ec.Free Cool OAT Lock
Economizer Trim for Sum Z? (E.TRM) — Sum Z is the
adaptive cooling control algorithm used for multiple stages
of mechanical cooling capacity. The configuration option,
E.TRM is typically set to Yes, and allows the economizer to
modulate to the same control point (Sum Z) that is used to
control capacity staging. The advantage is lower compressor
cycling coupled with tighter temperature control. Setting this
option to No will cause the economizer, if it is able to provide
free cooling, to open to the Economizer Max. Position
(EC.MX) during mechanical cooling.
ECONOMIZER OPERATION — There are four potential
elements which are considered concurrently which determine
whether the economizer is able to provide free cooling:
1. Dry bulb changeover (outside-air temperature qualification)
2. Economizer switch (discrete control input monitoring)
3. Economizer changeover select (E.SEL economizer
changeover select configuration option)
4. Outdoor dewpoint limit check (requires an installed out-
door relative humidity sensor installed)
Dry Bulb Changeover (OAT.L) — Outside-air temperature
may be viewed under Temperatures
trol constantly compares its outside-air temperature reading
against the high temperature OAT lockout (OAT.L). If the tem-
perature reads above OAT.L, the economizer will not be al-
lowed to perform free cooling.
Economizer Switch (EC.SW) — The state of the economizer
switch can be viewed under Inputs
function of this input is determined by Configuration
→
CON EC.SW.
When set to EC.SW = 0, the switch is disabled. When set to
EC.SW = 1, the economizer switch functions to enable/disable
the economizer. When set to EC.SW = 2, the switch functions
as an IAQ override switch. This functions just like the discrete
→
IAQ input Inputs AIR.Q
→ → →
IAQ AQ.CF IQ.I.C=2 (IAQ Discrete Override). See the
Indoor Air Quality Control section for more information.
→
When Configuration ECON
→
GEN.I E.SW = No, free cooling will not be allowed.
Economizer Changeover Select (E.SEL)The control is capa-
ble of performing any one of the following changeover types in
addition to both the dry bulb lockout and the external switch
enable input:
E.SEL = 0 none
E.SEL = 1 Differential Dry Bulb Changeover
E.SEL = 2 Outdoor Enthalpy Changeover
E.SEL = 3 Differential Enthalpy Changeover
Table 73 — Economizer Configuration Table
EXPANSION
→ →
AIR.T OAT. The con-
→ →
GEN.I E.SW. The
→
→
IAQ.I when Configuration
→
EC.SW=1 and Inputs
RANGE
Yes/No
0 - 100 %
0 - 100 %
Yes/No
0 - 3
1 - 5
18 - 28
-40 - 120 dF
50 - 62 dF
Enable/Disable
1 - 3
0 - 2
0.7 - 3.0
0.5 - 5 ^F
0.1 - 10
0.1 - 2 ^F
0-2
0 - 720 min
40 - 70 dF
Differential Dry Bulb Changeover — As both return air and
outside air temperature sensors are installed as standard on
these units, the user may select this option, E.SEL = 1, to
perform a qualification of return and outside air in the enabling/
disabling of free cooling. If this option is selected and outside-
air temperature is greater than return-air temperature, free
cooling will not be allowed.
Outdoor Enthalpy Changeover — This option should be used
in climates with higher humidity conditions. The A Series
control can use an enthalpy switch or enthalpy sensor, or the
standard installed outdoor dry bulb sensor and an accessory
relative humidity sensor to calculate the enthalpy of the air.
Setting Configuration
the user configure Configuration
Outdoor Enthalpy Changeover Select, and install an outdoor
relative humidity sensor. Once the sensor is installed, enable
→
Configuration
ity sensor configuration option.
If the user selects one of the Honeywell curves, A,B,C or D,
then OA.E.C options 1-4 should be selected. See Fig. 8 for a
diagram of these curves on a psychrometric chart.
OA.E.C = 1 Honeywell A Curve
OA.E.C = 2 Honeywell B Curve
OA.E.C = 3 Honeywell C Curve
OA.E.C = 4 Honeywell D Curve
OA.E.C = 5 custom enthalpy curve
If the user selects OA.E.C = 5, a direct compare of outdoor
E-
enthalpy versus an enthalpy set point is done. This outdoor
enthalpy set point limit is configurable, and is called
→
Configuration
Depending on what Configuration
configured for, if the outdoor enthalpy exceeds the Honeywell
curves or the outdoor enthalpy compare value (Configuration
→ →
ECON OA.EN), then free cooling will not be allowed.
Differential Enthalpy Changeover — This option compares
the outdoor-air enthalpy to the return air enthalpy and chooses
→
the option with the lowest enthalpy. This option should be
used in climates with high humidity conditions. This option
uses both humidity sensors and dry bulb sensors to calculate
the enthalpy of the outdoor and return air. An accessory
outdoor air humidity sensor (ORH.S) and return air humidity
sensor (RRH.S) are used. The outdoor air relative humidity
sensor config (ORH.S) and return air humidity sensor config
→
(Configuration
58
UNITS CCN POINT
ECON_ENA
ECONOMIN
ECONOMAX
ECONTRIM
ECON_SEL
OAEC_SEL
OAEN_CFG
OAT_LOCK
OADEWCFG
OARHSENS
ECON_CTL
ECOSWCFG
EC_PGAIN
EC_RANGE
EC_SPEED
EC_DBAND
UEFC_CFG
UEFCTIME
UEFCNTLO
→ →
ECON E.SEL = 2 requires that
→
ECON
→
ECON ORH.S, the outdoor relative humid-
→
ECON OA.EN.
→
ECON
→
SENS RRH.S) must be enabled.
DEFAULT
Yes
5
98
Yes
0
4
24
60
55
Disable
1
0
1
2.5
0.75
0.5
0
120
50
→
OA.E.C, the
→
OA.E.C is