In this column, I will describe the “issue” disclosed through analysis of the trend graph included in my April 2012 “Commissioning” column. I will also introduce a new system, show its trend graph, and then leave it up to the reader to discover the operational issue illustrated in the graph. The answer will be given at the start of next month’s column.
Last month’s trend graph showed about one week of 5-min interval data from the BAS for selected points in a central heating hot water boiler system. The system consisted of two high-efficiency modulating condensing hot water boilers with primary boiler pumps injecting hot water into a secondary variable flow distribution loop. These boilers were located in a northern climate where winter heating and summer reheat are both critical for maintaining space temperature and humidity criteria.APRIL 2012 TREND LOG ANALYSIS