RT-SVX50M-EN
29
Table 7. Enthalpy operation no DCV (CO
2
sensor) - 2 speed fan
DCV
OA Good to
economize?
Y1-I Y2-I FAN SPD Y1-O Y2-O
Occupied Unoccupied
NO CO
2
SENSOR
No
Off Off Low 0-v/Off 0-v/Off MIN POS L Closed
On Off Low 24-v/On 0-v/Off MIN POS L Closed
On On
High
24-v/On 24-v/On MIN POS H Closed
Yes
Off Off Low 0-v/Off 0-v/Off MIN POS L Closed
On Off Low 0-v/Off 0-v/Off
MIN POS L to Full-Open Closed to Full-Open
On On
High
DELAY 24-v/On
(a)
0-v/Off
(b)
MIN POS H to Full-Open Closed to Full-Open
(a)
With 2SP FAN DELAY (Advanced Setup Menu) when in the economizing mode there is a delay for the high speed fan to try to satisfy the call for second stage cooling by
turning on the fan to high and opening the OA damper 100% before the first stage mechanical cooling is enabled.
(b)
With stage 3 delay (STG3 DLY) in Advanced setup menu can turn on 2nd stage of mechanical cooling Y2 -O after the delay if the call for Y1-I and Y2-I have not been
satisfied.
Table 8. Enthalpy operation with DCV (CO
2
sensor) - 2 speed fan
DCV
OA Good to
economize?
Y1-I Y2-I FAN SPD Y1-O Y2-O
Occupied Unoccupied
Below set
No
Off Off Low 0-v/Off 0-v/Off VENTMIN L Closed
On Off Low 24-v/On 0-v/Off VENTMIN L Closed
On On
High
24-v/On 24-v/On VENTMIN H Closed
Yes
Off Off Low 0-v/Off 0-v/Off VENTMIN L Closed
On Off Low 0-v/Off 0-v/Off
VENTMIN L to Full-Open Closed to Full-Open
On On
High
24-v/On
0-v/Off
(a)
VENTMIN H to Full-Open Closed to Full-Open
Above set
No
Off Off Low 0-v/Off 0-v/Off VENTMIN L to VENTMAX Closed
On Off Low 24-v/On 0-v/Off VENTMIN L to VENTMAX Closed
On On
High
24-v/On 24-v/On VENTMIN H to VENTMAX Closed
Yes
Off Off Low 0-v/Off 0-v/Off VENTMIN L to VENTMAX Closed
On Off Low 0-v/Off 0-v/Off
VENTMIN L to Full-Open Closed to Full-Open
On On
High
DELAY 24-v/On
(b)
0-v/Off
(a)
VENTMIN H to Full-Open Closed to Full-Open
(a)
With stage 3 delay (STG3 DLY) in Advanced setup menu can turn on 2nd stage of mechanical cooling Y2-O after the delay if the call for Y1-I and Y2-I have not been
satisfied.
(b)
With 2SP FAN DELAY (Advanced Setup Menu) when in the economizing mode there is a delay for the high speed fan to try to satisfy the call for second stage cooling by
turning on the fan to high and opening the OA damper 100% before the first stage mechanical cooling is enabled.
Economizer Set-Up
Adjusting the minimum position (MIN POS/VENTMAX on
the SETPOINTS menu) sets the required amount of
ventilation air.
Ambient temperature controls the economizing cycle by
sensing the outside air dry bulb temperature. Table 9, p. 29
lists the five selectable dry bulb values (ENTH CURVE) on
the SETPOINTS menu.
Table 9. Single enthalpy and dual enthalpy boundaries (parameters ES1 through ES5)
Enth. Curve
Temp. dry-Bulb (ºF)
Temp. dewpoint
(ºF)
Enthalpy (btu/lb/
da)
Point P1 Point P2
Temp. ºF
Humid.% RH
Temp. ºF
Humid.% RH
ES1 80.0 60.0 28.0 80.0 36.8 66.3 80.1
ES2 75.0 57.0 26.0 75.0 39.6 63.3 80.0
ES3 70.0 54.0 24.0 70.0 42.3 59.7 81.4
ES4 65.0 51.0 22.0 65.0 44.8 55.7 84.2
ES5 60.0 48.0 20.0 60.0 46.9 51.3 88.5
HL 86.0 66.0 32.4 86.0 38.9 72.4 80.3
Note: For differential enthalpy there is a high limit boundary. The high limit boundary is ES1 when there are no stages of mechanical cooling energized and HL
when a compressor stage is energized.
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