2 Speed Fan Operation; Economizer Operation - Fan Type = 2Speed - Carrier 50FC Series Service And Maintenance Instructions

2 Speed Fan Operation

NOTE: 2 Speed Fan operation applies to 50FC-*07 models only.
The W7220 controller has the capability to work with a system
using a 2 speed supply fan. The W7220 does not control the
supply directly but uses the following input status to determine
the speed of the supply fan and controls the OA damper to the
required position, see Table 15.
Table 15 — Fan Speed
STATE
OCC
Y1
Y2
W
DEMAND
OUTSIDE AIR
CONTROLLED
GOOD TO
VENTILATION
ECONOMIZE
(DCV)
NO
NONE
YES
NO
Below CO2 Set
YES
NO
Above CO2 Set
YES
*With stage 3 delay (STG3 DLY) in Advanced setup, COOL Y2-OUT will be turned ON after the delay time specified.
N/A = Not applicable
FAN SPEED
Low
Low
High
High
Table 16 — Economizer Operation - FAN TYPE = 2SPEED
INPUTS
W COOL
(HEAT ON) Y1-IN
ON N/A
OFF OFF
OFF ON
OFF ON
ON N/A
OFF OFF
OFF ON
OFF ON
ON N/A
OFF OFF
OFF ON
OFF ON
ON N/A
OFF OFF
OFF ON
OFF ON
ON N/A
OFF OFF
OFF ON
OFF ON
ON N/A
OFF OFF
OFF ON
OFF ON
The W (heating mode) is not controlled by the W7220 but it re-
quires the status to know where to position the OA damper for
minimum position for the fan speed.
The 2 speed fan delay is available when the system is pro-
grammed for 2 speed fan (in the System Setup menu item). The
2 speed fan delay is defaulted to 5 minutes and can be changed
in the Advanced Setup menu item. When the unit has a call for
Y1 In and in the free cooling mode and there is a call for Y2 In,
the 2-speed fan delay starts and the OA damper will modulate
100% open, the supply fan should be set to high speed by the
unit controller.
After the delay one of two actions will happen:
• The Y2 In call will be satisfied with the damper 100%
open and fan on high speed and the call will turn off
OR
• If the call for additional cooling in the space has not been
satisfied then the first stage of mechanical cooling will be
enabled through Y1 Out or Y2 Out.
Refer to Table 16 for economizer operation.
FAN SPEED
COOL COOL COOL
Y2-IN Y1-OUT Y2-OUT
N/A OFF OFF
OFF OFF OFF
OFF ON OFF
ON ON ON
N/A OFF OFF
OFF OFF OFF
OFF OFF OFF
ON ON OFF*
N/A OFF OFF
OFF OFF OFF
OFF ON OFF
ON ON ON
N/A OFF OFF
OFF OFF OFF
OFF OFF OFF
ON ON OFF*
N/A OFF OFF
OFF OFF OFF
OFF ON OFF
ON ON ON
N/A OFF OFF
OFF OFF OFF
OFF OFF OFF*
ON ON OFF*
50
OUTPUTS
DAMPER POSITION
(reference
OCCUPIED
only)
HIGH MIN POS H
LOW MIN POS L
LOW MIN POS L
HIGH MIN POS H
HIGH MIN POS H
LOW MIN POS L
MIN POS L to
LOW
Full Open
MIN POS H to
HIGH
Full Open
HIGH VENTMIN H
LOW VENTMIN L
LOW VENTMIN L
HIGH VENTMIN H
HIGH VENTMIN H
LOW VENTMIN L
VENTMIN L to
LOW
Full Open
VENTMIN H to
HIGH
Full Open
VENTMIN H to
HIGH
VENTMAX H
VENTMIN L to
LOW
VENTMAX L
VENTMIN L to
LOW
VENTMAX L
VENTMAX H to
HIGH
VENTMAX H
VENTMIN H to
HIGH
VENTMAX H
VENTMIN L to
LOW
VENTMAX L
VENTMIN L to
LOW
Full Open
VENTMIN H to
HIGH
Full Open
UNOCCUPIED
Closed
Closed
Closed
Closed
Closed
Closed
Closed to
Full Open
Closed to
Full Open
Closed
Closed
Closed
Closed
Closed
Closed
Closed to
Full Open
Closed to
Full Open
Closed
Closed
Closed
Closed
Closed
Closed
Closed to
Full Open
Closed to
Full Open