GRAPH #2 GRAPH #2 shows the relationship of the supply water temperature with respect to the actual amount of heat required by the coldest room on the system. This graph illustrates the performance of an Energy Conservation System Circuit. Sensing point (F) on FIGURE #2 is the location where the supply water temperature readings were obtained and sensing point (I) on FIGURE #2 is the location where the Energy Conservation Demand Temperature Signal readings were obtained. The Energy Conservation Demand Temperature Signal is created by the demand of the coldest room in the system. The Energy Conservation Demand Temperature Signal "tells" the main heating controller that the outside temperature is warmer than the actual outside condition to allow the system to attain the exact temperature in the supply water to satisfy the building’s requirement. A multi-selector determines the heating requirement of the coldest room. It selects the lowest signal to indicate the true requirement for heating. Relays are used to offset the coldest room’s signal such that it will create an Energy Conservation Demand Temperature Signal of 60°F any time the room has either started to close off its heating device or has closed off its heating device. The only time the coldest room is allowed to ask for more than the minimum level of heat from the main system is after the room thermostat has opened its heating device to maximum flow. This delivers the required BTUs to the room with the minimum degree of temperature in the supply water. Graph #2 illustrates the supply water temperature dropping when the body load of the students and other internal heat sources are generating enough heat to lessen the load on the heating system. The water temperature rises at night and at lunch when the other heat sources have been removed from the classrooms. It is worth observing that the supply water temperature graph is symmetrical to both the actual outside air temperature graph as well as to the Energy Conservation Demand Temperature Signal graph on both Graph #1 and Graph #2. The difference is that Graph #1 is using open loop logic which makes the poor assumption that the outside air temperature is the only factor required to determine the heating supply water temperature and Graph #2 is using closed loop logic which assesses the actual heating requirements of the building. 8.133
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