Optimum Stop

Optimum Stop without Room Temperature Sensor

When the next switching point of the room temperature setpoint in the time schedule is less than the previous value, the optimize flag is checked and the input “OptimEnable” has one of the values 3 or 4, than the macro will calculated the time of optimum stop. The maximum optimum stop time is 2 hours. Optimum stop can only occur when the outside air temperature is higher than OOFF-01, minimum outside air temperature for optimum stopping.

If outdoor air temperature is less than the limit defined by parameter P4, no early switch-off occurs. Between these two points, EOH3 uses the following linear interpolation to advance switch-off point tVV:

tVV = 120 min* (FilteredOATemp – OOFF-01) / (RoomTempSp – OOFF-01)

Parameter OOFF-10 influences the switch off time as shown in the figure below.

Fig. 20.   Optimum stop without room temperature sensor


Table 21.   Parameter List

Description

Value Range

Default Value

Unit

OOFF-01: minimum OAT for optimized stop

-50...50

0

°C

OOFF-02: optimum stop factor

0...100

10

min/k


Optimum Stop with Room Temperature Sensor

Cool-down optimization with a room sensor operates with the same principles as without a room sensor but it also takes into account room temperature:

The macro calculates the early off time with room sensor (tVVR) with the following formula:

tVV = (120 min + tcorr)* (FilteredOATemp – OOFF-01) / (RoomTempSp – OOFF-01)

Where

tcorr =(RoomTemp – RoomTempSp ) * OOFF-02

which means: room temperature minus setpoint times optimum stop factor.

If the parameter OOFF-02 is zero, the cool-down optimization procedure with room sensor is the same as without a room sensor.


To allow optimum stop to save a significant amount of energy without losing comfort, the room temperature can drop by OOFF-04 below the actual room temperature setpoint. In this moment the macro switches to room control mode with the room temperature setpoint equal to actual room temperature setpoint – OOFF-03 and keeps this setpoint until the start time of the next lower setpoint. The room temperature control uses an internal controller which integral action time (RCTR-02) and room controller P-band (RCTR-01) can be set.

Fig. 21.   Pre-start with room temperature sensor

After reaching the target time, EOH3 still works with the mixed water temperature setpoint from the heating curve.


When preparing the Time Schedule, ensure that the switch point for cool-down is always the latest possible time in the Time Schedule to avoid premature cool-down and room temperatures outside the comfort zone.


Table 22.   Parameter List

Description

Value Range

Default Value

Unit

OOFF-01: minimum OAT for optimized stop

-50...50

0

°C

OOFF-02: optimum stop factor

0...100

10

min/K