EXCEL CARE CONTROL ICONS EXAMPLES
247 74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)
Average Value Calculation
Purpose The implementation of some heating limit functions require an average of outdoor air
temperature (OAT) over three days.
The formula for this calculation is:
Y
Average, new
= (n*Y
Average, old
+ X )/(n + 1) where n varies from 0 to i.
Average, new is the momentary average value.
Average, old is the average value calculated in the previous cycle.
X is the actual value of the variable that is being averaged.
The variable n serves to weight the average value relative to the actual value. As
time increases, the weighting of the actual value always becomes less. The variable
i serves to limit n. The following formula defines this limitation:
i = T/t0 where T = Averaging duration and t0 = scan time.
If n reaches the value of i, it must remain fixed at this value.
To average temperature over three days, measure OAT every 10 minutes, that is,
scan time (t0) is 10 minutes. Averaging duration T is 3 days or 4220 minutes. So, i is
4220/10 or 422.
The formula to average three days of OAT (oat_72h) is then:
oat_72h = (n*oat_72h + OAT)/(n + 1) where n varies from 0 through 422 and
increases by 1 every 10 minutes.
Flowchart The following flowchart illustrates this averaging.
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