1
How the BCP-3 operates...
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
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
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).
INSTALLATION/OPERATING INSTRUCTIONS
BCP-3
Hot Water Reset Control
For up to 3 Boilers
Outdoor Temperature (in °F)
70
60
50
40
20
30
0
-10
10
-20
W
a
ter
Tem
per
atur
e (
in
°F)
100
120
110
130
140
150
160
180
170
190
200
210
220
12 11
10
9
8
7
6
4
3
2
5
1
1:4 1:3
1:2
1:1.5
1:1.25
1:1
1.25:1
1.5:1
2:1
3:1
4:1
8:1
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.
W A R N I N G
Part Number 550-141-696/1200
