Viconics VT7600 Installation Guide (First Release 1000 Series) - Manual (Page 20)

20
Economizer Model only
Chngstpt
Changeover setpoint
Default value = 55 °F ( 13.0 °C )
In Cooling mode.
The outside air temperature value at which the
cooling will be switched over from mechanical (
compressor ) to free cooling ( economizer )
14 to 70 °F ( -10.0 to 21.0 °C )
min pos
Minimum position
Default value = 0%
Outside air damper minimum position.
Will be active only when fan is on ( G terminal )
and the internal or remote scheduling is in
occupied mode.
When internal or remote scheduling is in
unoccupied mode and/or fan is off, minimum
position will be set to 0%
0 to 100 %
= 0 to 10 Vdc output range
C mech
Mechanical cooling allowed
Default value = Off
In Cooling mode.
Allows the operation of the mechanical cooling if
the free cooling ( economizer ) cannot maintain the
cooling setpoint.
Off Typically applies when the MS ( mixed air
temperature sensor ) is installed after the
mechanical cooling refrigeration coils. In this case,
mechanical cooling will never operate at the same
time as free cooling.
On Typically applies when the MS ( mixed air
temperature sensor ) is installed before the
mechanical cooling refrigeration coils in the mixing
plenum. In this case, mechanical cooling is
allowed when the free cooling ( economizer
operation ) cannot maintain the cooling setpoint.
Off or On
mix stpt
Mixed air setpoint
Default value = 55 °F ( 13.0 °C )
Free cooling mixed air setpoint when economizer
mode is enabled.
50 to 90 °F ( 10.0 to 32.0 °C )
MS dis
Display mixed air temperature
Economizer model only, only if sensor
is installed
Used as diagnostic / service help to troubleshoot
and diagnose economizer operation.
Outside air
percentage
0% 5% 10% 15% 20% 25% 30%
Setting for 0-10
Vdc Autuator
0% 5% 10% 15% 20% 25% 30%
Setting for 2-10
Vdc Autuator 0 to
20% 24% 28% 32% 36% 40% 44%