The BCP-3 is a multi-boiler or multi-stage outdoor reset hydronic heating control. It establishes ambient comfort by varying the temperature of the heating system’s circulating hot water in response to changes in the outdoor temperature. In addition, it provides an outdoor temperature based cutoff, heating system pump control, and domestic hot water (DHW) pump control. Two unique features have been added to this control including a customized reset ratio curve. A Set Point option was added for applications where outdoor reset will not apply.

Two sensors are used, one to monitor the outdoor temperature and one to monitor the circulating hot water temperature in the heating system. When the outdoor temperature falls below the outdoor cutoff setting, the heating system is activated and the target water temperature is increased proportionally to satisfy the load. Should it get warmer outdoors, the target water temperature is automatically lowered by the control. If the outdoor temperature continues to rise to the outdoor cutoff setting then the heating system is turned off.
 

Because of the many different physical characteristics of buildings including the type of radiation; i.e., baseboard or radiant, the heat loss varies. In one building, a 1-degree outdoors temperature change may require a change of 1 degree in heating water temperature; for another it may require a change of 2, 3, or even 4 degrees in order to gain the desired comfort level. This is known as the Reset Ratio. The Reset Ratio chart shows the wide range of Reset Ratios available for the BCP-3 in addition to the customized reset ratio.