GRAPH #4 ENERGY CONSERVATION DEMAND SIGNAL ACTUAL OUTDOOR AIR TEMPERATURE HOT WATER SUPPLY TEMPERATURE BASED ON CONSERVATION DEMAND SIGNAL HOT WATER SUPPLY TEMPERATURE BASED ON OUTDOOR AIR TEMPERATURE 58°F 140°F 155°F 60°F 120°F 32.7°F 107°F 106°F 98°F 88°F 5°F APS -152°F 6:00 12:00 6:00 12:00 6:00 12:00 6:00 12:00 6:00 12:00 6:00 12:00 6:00 PM AM AM PM PM AM AM PM PM AM AM PM PM This graph compares the building's original hot water reset schedule's design performance to a system that allows the zone with the greatest requirement for heat to set the heating water temperature in coordination with the heating device and the cooling device serving that zone. The cooling function must be off and the heating function must be positioned to full flow before the heating water temperature is allowed to rise as the coolest zone continues to drop in temperature. This allows the coolest zone to be held in the comfort range with the lowest temperature in the supply water possible. The hot water supply temperature is limited by the original outdoor reset schedule. For systems with modulating control valves the heating requirement of the most demanding room can also be coordinated with varying the flow rates controlled by the heating pumps' VFD's. Please note that as the outside air temperature dropped this day the supply water temperature would have risen, based on the reset schedule; however, the energy conservation demand signal determined that the water temperature should have done the opposite, and reduce the hot water supply temperature to match the requirement of the coolest of the sample rooms. 5.43F
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