ECO MODE
The Eco mode is referenced to a period by the Shortfall. The shortfall coefficient always refers to
a period of 60 minutes. For a demand temperature T.dem. of 50 °C, a shortfall of 20 % has the
following effect: demand after 30 minutes below 30 °C or after one hour below 40 °C (= 20 %) or
after two hours below 45 °C. Under 30 minutes the threshold value remains the same.
Formula: dT * dt = shortfall * set demand temperature value = constant
Example:
Demand temperature = 50 °C
Shortfall = 20 %
=> 20 % of 50 °C = 10 K
dt= 30 min => dT= 20 K
dt= 60min => dT= 10 K
dt= 120min => dT= 5 K
dt= 240 min => dT= 2.5 K
dt= 480 min => dT= 1.25 K
dt= 1440 min => dT= 0.42 K
The demand status changes to ON if the actual demand temperature is 20 K below the set value for
30 minutes or if the actual demand temperature is 0.42 K below the set value for 1440 minutes
(= 1 day).
The curve is limited at the point where it falls to more than twice the shortfall * the set demand
temperature value (which equates to the value at 30 min). If the differential between the set
demand value and the actual value of the demand temperature is greater than twice the shortfall *
the set demand temperature value, the burner starts immediately (such as when the heating circuit
changes over from setback to standard mode or when a shutdown condition is no longer met and
the heating circuits start up again).
The heating demand is terminated when, in cases where one sensor is used, the temperature
T.dem. set + Diff. off is exceeded or, in cases where two sensors are used, the temperature T.dem.
set + Diff. off is exceeded at the shutdown sensor.
In practice, neither the demand temperature nor the set value will be constant. The difference
between the two values normally becomes ever greater over time, so an ever greater product of
dT*dt is continually added to the sum register and compared to the curve. This will be the case
unless, for example, the heating circuits change over from standard mode to setback or if the
heating circuit pump stops completely due to a shutdown condition, etc. However, in such cases the
energy is saved that the burner would have consumed if it had started immediately when the
demand temperature fell below the set value. At certain intervals, the program calculates the
differential between the set demand value and the actual value of the demand temperature. If that
sum is greater than the product of the shortfall * the set demand temperature value with reference
to one hour – and allowing for the immediate starting of the burner when the curve is below twice
the shortfall – then the burner starts.
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