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INSTALLATION/OPERATING INSTRUCTIONS
The BCP-3 establishes ambient comfort by varying the tempera-
ture of the heating system's circulating hot water in response to
changes in the outdoor temperature. In addition, it provides an
outdoor temperature based start/stop and system pump control
for systems with less than 3 boilers.
Two sensors are used, one to monitor the outdoor temperature,
and one to monitor the temperature of the circulating hot water
in the heating system. When the outdoor temperature falls to
the outdoor starter setting, the
heating system is activated
and the hot water temperature
is increased proportionally to
meet the need for more heat.
Should it get warmer outdoors,
the hot water temperature is
automatically lowered by the
control. If the outdoor
temperature continues to rise
to the outdoor starter setting
then the heating system is
turned off.
Because of many physical
characteristics, and the type of
radiation, ie. baseboard or
radiant, heat loss varies. In
one building, a 1-degree
temperature change outdoors
may require a change of 1
degree in heating water
temperature; for another it may
require a change of 2, 3, or
W A R N I N G
BCP-3
Hot Water Reset Control
For up to 3 Boilers
How the BCP-3 operates...
1:4 1:3
12 11
220
210
200
190
180
170
160
150
140
130
120
110
100
70
60
50
40
30
Outdoor Temperature (in °F)
This manual must only be used by a qualified heating installer/service
technician. Failure to comply could result in severe personal injury, death or
substantial property damage.
even 4 degrees in order to gain the desired comfort level. This
is known as the reset ratio. The middle chart shows the wide
range of reset ratios available for the BCP-3.
The installer fits the BCP-3 to a specific building by adjusting
the reset ratio curve. With a curve of 4 (2:1 reset ratio) a 2-
degree change in outdoor temperature will change the circulat-
ing hot water temperature by 1 degree; at an 11 curve (1:3 reset
ratio) an outdoor change of 1 degree will change the water
1:2
1:1.5
10
9
8
1:1.25
7
1:1
6
1.25:1
5
1.5:1
4
2:1
3
3:1
2
4:1
1
8:1
20
10
0
-10
-20
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 optional external heat
demand input can be connected
to the BCP-3 This can be
connected to a new or existing
thermostat or switch to shut the
heating system down when the
thermostat is satisfied.
The BCP-3 can control all the
following types of systems: one
boiler with system pump, one
lo/hi fire boiler with system
pump, two boilers with system
pump, or three boilers (system
pump output must be provided
separately).
Part Number 550-141-696/1200
1
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Related Manuals for Weil-McLain BCP-3
Summary of Contents for Weil-McLain BCP-3
- Page 1 3 boilers. The installer fits the BCP-3 to a specific building by adjusting the reset ratio curve. With a curve of 4 (2:1 reset ratio) a 2-...
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Page 2: Installation
• Mount the unit away from excessive heat or cold. Ambient operating temperature is from 20 to 120°F. • After completing all the wiring connections (see below) use the two screws provided to mount the BCP-3 to the 1900 box. - Page 3 • If the HEAT DEMAND inputs are open, the BCP-3 will not energize any output stages. • The BCP-3 is shipped with a jumper across the HEAT DEMAND inputs. DO NOT remove this jumper unless you replace it with a dry contact switch which is closed when heat is required in the system.
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Page 4: Default Settings
INITIAL CONTROL START-UP • Whenever the BCP-3 is powered up, it will display the software version number and then the current operating parameters. Each display will remain on the screen approximately 5 seconds. If the parameters are correct, there is no need to make any adjust- ments. -
Page 5: Operation
Calculated water temperature Center button pressed once • This is the water temperature the BCP-3 will stage units to hold. It is based on outdoor temperature and the Fine Tune and Reset Ratio values (described in the following sections). • The Calculated water temperature can not be less than the Minimum Water temperature setting (see opposite page). - Page 6 • The other Reset Ratios are shown on the first page. • The Reset Ratio curves start at 70°F. At 70°F the BCP-3 will require 100°F water. Note that this is not the point where the BCP-3 will begin giving heat. That point is determined by the Outdoor Starter. Also note this starting point can be changed by adjusting the Fine Tune as shown above.
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Page 7: Heat Demand
• When the HEAT DEMAND input terminals are open, the BCP-3 will not energize any stages. • The BCP-3 comes equipped with a factory installed jumper across the HEAT DEMAND terminals. DO NOT remove this jumper unless it is being replaced by a dry contact switch. -
Page 8: Troubleshooting
Remove any connections to the Black System Pump wires. Test for continuity across the System Pump output. If the wires are continuous, the BCP-3 is calling for the System Pump to run. Check the pump to determine why it is not circulating.