DRAWING FIVE SYSTEM AFTER LOGIC CORRECTIONS Drawing five illustrates the control arrangement now controlling on site with the sequence of operation. The performance chart illustrated on drawing four is achieved by this control system. The high limit (HL1) is moved to sense the return air temperature at all times. TT1 is moved to sense the true return air temperature. It is interesting to note that the same number of instruments were required to achieve the logic system in drawing five as the first conservation attempt, as illustrated in drawing three. GENERAL The enthalpy circuit was not installed at the time of writing this report. The minimum ventilation is being controlled as per the original design at the time of writing this report. Two potential opportunities relating to energy reduction that required further investigation are: -1- The fan could possibly be duty cycled, at unoccupied times, to a night set back temperature. This would save energy relating both to the heating and the electrical consumption. -2- The minimum ventilation rate is 27% on the fan as it is currently running. The return fan has inlet vanes currently set at a fixed point. If the exhaust fans run intermittently, the opportunity may exist to reduce the minimum ventilation rates automatically based on the pressure differential from the laboratory to atmosphere. This case study is the approach employed for one system in one building. The responsibility rests on the individual designer using any techniques presented in this report. The focus must remain on the safety and well being of the building occupants and the building. The only energy available for savings is the energy consumed by illogical control. 8.76
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