25
ECONOMIZER ACTUATOR COMMUNICATION
The economizer actuator used with the 48/50HC units is a
Multi-Function Technology (MFT) actuator. This allows the
Comfort
Link system to communicate with the actuator digital-
ly using Belimo MP protocol. The configuration Economizer
Control Type (
Configuration
ECON
E.CTL
) determines
the communication method, either digital or analog, used to
communicate between the Economizer Control Board and the
economizer actuator.
NOTE: The power to the unit must be cycled after the Econo-
mizer Control Type (
Configuration
ECON
E.CTL
) con-
figuration parameter is changed.
E.CTL = 1 or 2 (Digital/Position or Digital/Command)
When Economizer Control Type (
Configura-
tion
ECON
E.CTL
) is set to 1, the Economizer Control
Board will communicate with the economizer actuator using
the digital protocol, from Economizer Control Board plug J7-1
to actuator pin 5. The commanded position and the actuators
actual position are communicated back and forth between the
actuator and the Economizer Control Board. When the Econo-
mizer Control Board and actuator first initiate communication,
a Control Angle (
Operating Modes
ECON
C.ANG
) is pro-
vided to the Economizer Control Board and defines the actua-
tor’s range of motion. The control angle must be greater than
the Min Actuator Ctrl Angle (
Configura-
tion
ECON
M.ANG
). During this digital control, the Econ-
omizer Control Board analog 4 to 20 mA output will represent
the actuator’s actual position when
E.CTL = 1
or commanded
position when
E.CTL = 2
. Because the wiring has a built-in
500-ohm resistor, the 4 to 20mA signal is converted to a 2 to
10VDC signal at the actuator.
E.CTL = 3 (Analog Control)
When
E.CTL
is set to 3, the Economizer Control Board will
NOT communicate with the actuator using digital MFT. It will
instead control the economizer actuator directly with the 4 to
20mA analog signal wired with the 500-ohm resistor produc-
ing a 2 to 10VDC signal for the actuator. While in this mode,
the actuator’s built-in 2 to 10VDC feedback signal can be read
as actual position any time because it is not used by the Econo-
mizer Control Board.
MINIMUM VENTILATION
The economizer will open to allow ventilation when the indoor
fan is turned on and the unit is in the occupied state. The econ-
omizer damper position at any given time for ventilation is dis-
played as the Min Position in Effect (
Run Sta-
tus
ECON
EC.MP
). This minimum position can be effect-
ed by the indoor fan speed (
F.SPD
) and indoor air quality. On
single speed units, the economizer minimum position will be
equal to the ECON MIN at MAX Fan Speed (
Configura-
tion
ECON
MP.MX
) unless Indoor air quality requests
something different.
On Staged Air Volume (SAV) units, to maintain a constant air-
flow through the economizer, as the indoor fan speed decreases
or increases, the damper minimum position will increase or de-
crease, respectively. This relationship curve is shown in Fig. 7.
Units can also be equipped with optional CO
2
sensors for addi-
tional indoor air quality control. When unit is equipped with a re-
turn duct CO
2
sensor or return duct CO
2
sensor and outside air
CO
2
sensor the Economizer minimum position will be recalculat-
ed based on the CO
2
level of the return and/or outside air. On
SAV units the fan speed will also be used in recalculating mini-
mum position, as shown in Fig. 7. When the Commanded Fan
Speed (
F.SPD
) is less than the Supply Fan Maximum Speed
(
FS.MX
) the damper will operate in the shaded area of Fig. 7
based on the IAQ Level (IAQ). See the Indoor Air Quality (IAQ)
section for more details on Demand Controlled Ventilation
(DCV).
Fig. 7 — Minimum Damper Position Curve (on SAV
units)
The shape of the Economizer Minimum Position vs. Fan Speed
curve is determined by the configuration parameters: Econ Min
at 25% Fan speed (
Configuration
ECON
MP.25
), Econ
Min at 50% Fan speed (
Configuration
ECON
MP.50
),
Econ Min at 75% Fan speed (
Configura-
tion
ECON
MP.75
) and Econ Min at Max Fan speed (
Con-
figuration
ECON
MP.MX
). These configurations are pre-
set at the factory for default purposes. The Econ Min at Max
Fan Speed (
MP.MX
) should be changed based on the air bal-
ance of the unit for proper ventilation. The Econ Min at 25%
Fan speed (
MP.25
), Econ Min at 50% Fan speed (
MP.50
) and
Econ Min at 75% Fan speed (
MP.75
) damper positions will be
calculated and changed automatically after changing the Econ
Min at Max Fan Speed (
MP.MX
) and Supply Fan Maximum
Speed (
Configuration
I.FAN
FS.MX
).
The damper position curve can be field adjusted per application,
if needed. The Econ Min at 25% Fan speed (
Configura-
tion
ECON
MP.25
), Econ Min at 50% Fan speed (
Configu-
ration
ECON
MP.50
) and Econ Min at 75% Fan speed
(
Configuration
ECON
MP.75
) damper position are user
configurable and can be determined by setting the fan speed at
25, 50 and 75% and determining the damper position required to
maintain the Econ Min at Max Fan Speed (
Configura-
tion
ECON
MP.MX
) outside air CFM through the econo-
mizer outside air dampers. The default calculations programmed
into the HC controls are based on a side shot economizer at 400
CFM/TON Supply Air flow with negative 0.25 in.wg H
2
O pres-
sure in the return duct. Econ Min at Max Fan Speed (
FS.MN
) is
set by user based on minimum required outside air ventilation
CFM required for the application. This procedure would be the
same as if this were a CV unit with the unit running at the design
point CFM. This determines the minimum position amount of
outside air CFM required when the fan is running at maximum
speed.
FREE COOLING
The economizer will be allowed to help with cooling (
Run Sta-
tus
MODE
OK.EC = Yes
) if the supply air temperature sen-
sor reading is valid, there are no applied lockouts, and there is
not a dehumidification demand. There are four economizer lock-
outs that can be applied at any time. Econo Cool OAT Lockout
(
Operating Modes
ECON
E.LOC
) occurs when the Outdoor
Air Temperature (OAT) is greater than the configured Econo
Cool Hi Temp Limit (
Configuration
ECON
EH.LO
) or less
Economizer Position %
50
0
100
25
75
EC.MX
Minimum
Fan Speed
0
0
1
0
50 75
0
2
5
2
Fan
Speed %
MP.MX
MP.75
MP.50
MP.25
AQ.MN for DCV
MP.75 DCV
MP.50 DCV
MP.25 DCV
Summary of Contents for /50HC 04-28
Page 69: ...69 Fig 24 Typical Control Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 70: ...70 Fig 25 Typical Power Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 71: ...71 Fig 26 Typical Control Diagram for 50HC 04 14 Units 50HC 14 shown ...
Page 72: ...72 Fig 27 Typical Power Diagram for 50HC 04 14 Units 50HC 14 Non Humidi MiZer shown ...
Page 73: ...73 Fig 28 Typical Control Diagram 48HC 17 28 Units ...
Page 74: ...74 Fig 29 Typical Control Diagram 50HC 17 28 Units ...
Page 75: ...75 Fig 30 Typical Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 76: ...76 Fig 31 Typical Non Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 89: ...89 Fig 42 Modulating ERV Wiring Schematic ...
Page 90: ...90 Fig 43 EnergyX ERV Control Box Component Layouts ...
Page 101: ...101 Fig 59 Exhaust Fan Assembly Removal Exhaust Fan Assembly ...
Page 141: ......