Sequence of Operation
RTU Open v3
Carrier Proprietary and Confidential
CARRIER CORPORATION ©2016
Integration Guide
All rights reserved
22
When the RTU Open schedule is unoccupied and the space temperature rises at least 1 °F (.5 °C) above the
Occupied Cooling Setpoint
, the supply fan starts. The economizer damper opens as necessary to cool the space.
The RTU Open continues to operate in this mode until the space is satisfied or the outside air conditions are no
longer suitable for free cooling.
Optimal Start
The RTU Open may use either of 2 different
Optimal Start
methods.
Learning Adaptive Optimal Start
is used for
heat pump applications and adjusts the effective setpoints to achieve the occupied setpoints by the time
scheduled occupancy begins. This prevents or minimizes the need for auxiliary heat. The Optimal Start recovery
period may begin as early as 4 hours prior to occupancy. The algorithm works by moving the unoccupied setpoints
toward the occupied setpoints. The rate at which the setpoints move is based on the outside air temperature,
design temperatures, and capacities.
The following conditions must be true for learning adaptive optimal start to operate:
•
On the
Properties
page >
Equipment
tab >
Configuration
>
Setpoints
>
Optimal Start
, the default value is set
to 1 and must be set greater than
0
(
0.00
disables
Optimal Start
) and less than or equal to
4
.
•
The system is unoccupied
NOTE
If the controller does not have a valid outside air temperature, then a constant of 65°F (18.3°C) is used.
This value is not adjustable.
The actual equation that the controller uses to calculate
Learning Adaptive Optimal Start
is nonlinear. An
approximation of the result is shown below.
NOTE
The values in the graph below are Fahrenheit.
To change
Learning Adaptive Optimal Start
settings:
1
In the navigation tree, select the equipment that you want to change.
2
Click
Properties
page
>
Equipment
tab >
Configuration
>
Setpoints
.