Honeywell EXCEL 5000 User Manual

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Honeywell EXCEL 5000 User Manual Manual pdf 245 page image

EXCEL CARE CONTROL ICONS EXAMPLES247 74-5577–33 (US)EN2B-0184 GE51 R0518 (Europe)Average Value CalculationPurpose The implementation of some heating limit functions require an average of outdoor airtemperature (OAT) over three days.The formula for this calculation is:YAverage, new = (n*YAverage, 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. Astime increases, the weighting of the actual value always becomes less. The variablei 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 is4220/10 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 andincreases by 1 every 10 minutes.Flowchart The following flowchart illustrates this averaging.