Weil-McLain BCP-3 manual Hydronic Multi-Stage Boiler Control

BCP-3

Hydronic Multi-Stage Boiler Control

INSTALLATION AND OPERATION INSTRUCTIONS

Hot Water Control with

Outdoor Reset, Set Point, and DHW for Hydronic Applications

2 Line Alphanumeric Display	Black (120VAC power)
Displays sensor values and	Output Lights indicate
menu settings
	output status

BCP-3

SYSTEM	=	147F
TARGET	=	150F
Boiler	SYS	DHW
	Pump	Pump
Output 1
	Output 2	Output 3

SET

Yellow (Output 1)

Blue (Output 2)

White (Output 3)

Display Section Locking Screws

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. See page 2.

The installer fits the BCP-3 to a specific building by adjusting the Reset Ratio curve. With curve number 4 (2:1 reset ratio) a 2-degree change in outdoor temperature will change the circulating hot water temperature by 1 degree; at curve number 11(1:3 reset ratio) an outdoor change of 1 degree will change the water temperature by 3 degrees. Most buildings with baseboard radiation require a curve of 6, 7, or 8. Radiant heat applications usually require a lower curve. An external T-Stat input can be used to shut the heating system down when the

WARNING This Weil McLain control is strictly an operating control; it should never be used as a primary limit or safety control. All equipment must have its own certified limit and safety

controls required by local codes. The installer must verify proper operation and correct any safety problems prior to the installation of this Weil McLain control.

Part Number 550-110-070/0308