Orion System SA Controller - Manual (Page 44)

Zone
Zone
Sequence of Operations
SA Controller Technical Guide 44
Heating Mode
Staging Up Delay
After the fi rst Heating Stage has been activated, this delay pre-
vents additional stages from activating too quickly before they are
needed to achieve the Active Supply Air Temperature Setpoint.
Staging Down Delay
After a Heating Stage has met its Minimum Run Time and is not
needed, this delay prevents additional stages from deactivating too
quickly in case they are needed to maintain the Active Supply Air
Temperature Setpoint.
The SA Controller 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 SA
Controller will modulate the Heat Source to achieve the Active Supply
Air Temperature Setpoint.
Modulating Hot Water or Steam Heating
One Stage of Heating needs to be confi gured for the Modulating Hot
Water or Modulating Steam Valve. When the Hot Water or Steam Valve
is active, the Valve will modulate to maintain the Active Heating Supply
Air Temperature Setpoint.
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 SA Controller can activate two forms of Heating that are classifi 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.
External Heat
The SA Controller can be confi gured to control heat sources that are
external to the SA Unit. Contact WattMaster Controls for options that
can be used in your application.
Air to Air Heat Pump Operation
The SA Controller can be confi gured for Heat Pump applications. The
compressors are used for both Heating and Cooling. With the SA Con-
troller, the Reversing Valve is activated during Heating operation as
the default because
AAON ® units are typically built to fail to Cooling
operation. The Reversing Valve can be confi gured to activate during
Cooling operation for equipment that is built to fail to Heating operation.
Auxiliary Heating Stages are confi gured as Heat Relays and are used to
supplement the Compressor Heating Stages. If the unit is not equipped
with Auxiliary Heating Stages, Heating Relays do not need to be confi g-
ured in order for the unit to provide Heating. Auxiliary Heating can also
be Modulating Heat in the form of SCR Electric, Hot Water, or Steam.
The Cooling and Dehumidifi cation Modes operate in the same manner
as described under the Cooling and Dehumidifi cation titled sections on
pages 39 through 43 of this manual. In the Heating Mode, the SA Con-
troller activates the Reversing Valve and stages compressors to provide
Heating if the Entering Air Temperature (EAT) is above the EAT Cooling
Lockout Setpoint. The compressor heating stages are activated as needed
to achieve the Active Supply Air Heating Setpoint. Staged or Modulating
Auxiliary Heat can be activated to supplement Compressor Heating in
order to achieve the Active Supply Air Heating Setpoint if the EAT is
below the EAT Heating Lockout Setpoint. If the EAT is below the EAT
Cooling Lockout Setpoint, only Auxiliary Heating will occur. If the EAT
is above the EAT Heating Lockout, only Compressor Heating will occur.
For SA applications with an installed Suction Pressure Transducer, a
Head Pressure Module and a Head Pressure Transducer(s), a Defrost
Mode is available during the Heat Pump Heating operation. The SA
Controller converts the Suction Pressure to a Suction Temperature.
A user-adjustable Suction Temperature Setpoint determines when the
unit will go into Defrost Mode during Heat Pump Heating. The unit
will operate in Defrost Mode for 10 minutes or until the Head Pressure
reaches 450 PSIG.
An Adaptive Defrost Adjustment confi guration is available that will
automatically adjust the length of the Defrost Timer (interval between
Defrost Modes) depending on if the unit stays in Defrost Mode for the
full 10 minutes or leaves the Defrost Mode early because of reaching a
Head Pressure of 450 PSIG. If Adaptive Defrost is confi gured and the
Defrost Mode is terminated because the 10 minute timer has elapsed,
this could indicate that the unit needs more defrost time. In this case,
the Adaptive Defrost Adjustment value will be subtracted from the
original Defrost Timer to shorten the interval between defrost cycles.
If the Defrost Cycle is terminated between the 8th and 9th minute, the
Defrost Timer value will not be changed. If the Defrost Cycle is termi-
nated before the 8th minute, this could indicate that the Defrost Timer
is too short. In this case the Adaptive Defrost Adjustment value will
be inversely proportionally added to the original Defrost Timer as the
termination time shortens from 8 minutes to 0 minutes.
Water Source Heat Pump Operation
For Water Source Heat Pump applications, the SA Controller is used
in conjunction with the Water Source Heat Pump Protection Module.
Heating, Cooling, and Dehumidifi cation would operate in the same man-
ner as described in Air to Air Heat Pump Operation; however, defrost
operation would not apply.
The Water Source Heat Pump Protection Module provides safeties for
Proof of Flow, Low/Unsafe Suction Pressure, and Low Leaving Water
Temperature. An E-BUS Distribution Module is used to provide com-
munication from the SA Controller to the Water Source Heat Pump
Protection Module.
For more detailed sequence and wiring information, see the AAON Tulsa
version of the Water Source Heat Pump Protection Module Technical
Guide.