Orion System VCM-X Modular E-BUS - Manual (Page 58)

Zone
Zone
SEQUENCE OF OPERATIONS
VCM-X Modular E-BUS Controller Technical Guide 58
Heating Mode
Modulating Heating
The VCM-X E-BUS supports various forms of Modulating Heat such as
SCR Electric Heat, Modulating Hot Water Heat, and Modulating Steam
Heat. Whichever form of Modulating Heating is used, the VCM-X E-
BUS will modulate the Heat Source to achieve the Active Supply Air
Temperature Setpoint. Modulating Natural Gas is a form of Modulat-
ing Heat, but is controlled by the AAON
® MODGAS Controller. The
VCM-X E-BUS only activates the AAON ® MODGAS as a stage of
heat; therefore, the Modulating Heating Proportional Window does not
apply when the VCM-X E-BUS is connected to the AAON
®
MODGAS
Controller and is the only form of Heating activated by the VCM-X.
The Modulating Heating Proportional Window is used to determine the
signal to the Modulating Heating Source and is user-adjustable. The
Modulating Heating Signal is calculated by the differential between
the Supply Air Temperature and the Active Supply Air Temperature
Setpoint based on the Modulating Heating Proportional Window. The
maximum signal adjustment per Time Period is 10% and is not user-
adjustable. The minimum signal adjustment per Time Period is based on
the Modulating Heating Proportional Window. The larger the Modulating
Heating Proportional Window, the smaller the signal adjustment will be
per Time Period. The Time Period is the delay between another increase
or decrease in the Modulating Heating source signal and is user-adjust-
able. For example, if the Modulating Heating Proportional Window is
5°F, the signal will be adjusted 2% per °F each Time Period above or
below the Active Supply Air Temperature Setpoint. When the Supply
Air Temperature is above or below the Active Supply Air Temperature
Setpoint by 5°F or more, the signal will adjust 10% each Time Period.
The VCM-X E-BUS can activate two forms of Heating that are clas-
sifi ed as Primary and Secondary Heat Sources. The Primary Heat
Source used can be SCR Electric Heat, Modulating Hot Water Heat,
or Modulating Steam Heat. The Secondary Heat Source used can be
Modulating Natural Gas (AAON
®
MODGAS Controller), Staged Gas
Heat, or Staged Electric Heat.
Primary Modulating Heat and Secondary Heat with
AAON
®
MODGAS Controller
The Modulating Heating Proportional Window is used to determine the
signal to the Primary Heat Source and is user-adjustable. The Heating
Stage Control Window is used to determine stage up and stage down
of the Secondary Heat Source. In the Heating Mode, the Primary Heat
Source will modulate to achieve the Active Supply Air Temperature
Setpoint. When the Primary Heat Source reaches 100%, the Heating
Stage Up Delay begins. If the Primary Heat Source is still at 100% after
the Heating Stage Up Delay expires, the Secondary Heat Source, which
is controlled by the AAON
® MODGAS Controller, will activate. The
Primary Heat Source will then be forced to 0%, allowing the AAON ®
MODGAS Controller to modulate the gas valve to achieve the Active
Supply Air Temperature Setpoint.
When the Secondary Heat Source reaches 100%, the Heating Stage Up
Delay begins. If the Secondary Heat Source is still at 100% after the
Heating Stage Up Delay expires, the Primary Heat Source will be forced
to 100%. The Primary Heat Source will remain at 100% to allow the
Secondary Heat Source to modulate to achieve the Active Supply Air
Temperature Setpoint. If the Supply Air Temperature rises above the
Active Supply Air Temperature Setpoint plus the Heating Stage Control
Window, the Heating Stage Down Delay begins. If the Supply Air Tem-
perature is still above the Active Supply Air Temperature Setpoint plus
the Heating Stage Control Window and the Heating Stage Down Delay
expires, the Primary Heat Source will forced to 0%. If the Secondary
Heat Source modulates to 0%, the Heating Stage Down Delay begins. If
the Secondary Heat Source remains at 0% and the Heating Stage Down
Delay expires, the Secondary Heat Source will be deactivated, and the
Primary Heat Source will modulate to achieve the Active Supply Air
Temperature Setpoint. If the Supply Air Temperature rises above the
Active Supply Air Temperature Setpoint plus the Heating Stage Control
Window, the Primary Heat Source modulates as needed to allow the
Supply Air Temperature to cool off.
Primary Modulating Heat and Secondary Heat with
Staged Gas or Electric Heat
The Modulating Heating Proportional Window is used to determine the
signal to the Primary Heat Source and is user-adjustable. The Heating
Stage Control Window is used to determine stage up and stage down
of the Secondary Heat Source. In the Heating Mode, the Primary Heat
Source will modulate to achieve the Active Supply Air Temperature
Setpoint. When the Primary Heat Source reaches 100%, the Heating
Stage Up Delay begins. If the Primary Heat Source is still at 100% after
the Heating Stage Up Delay expires, the Secondary Heat Source will
activate. The Primary Heat Source will then modulate to achieve the
Active Supply Air Temperature Setpoint. If the Secondary Heat Source
is activated and the Primary Heat Source has modulated to 0%, the
Heating Stage Down Delay will begin. If the Primary Heat Source is
still at 0% after the Heating Stage Down Delay expires, the Secondary
Heat Source will deactivate. If the Supply Air Temperature rises above
the Active Supply Air Temperature Setpoint plus the Heating Stage
Control Window, the Primary Heat Source will modulate to 0% to allow
the Supply Air Temperature to cool off.