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Room Occupied and Unoccupied
The Room setting is the desired temperature of the building.
When a programmable schedule is used, there are both Room
Occupied and Room Unoccupied settings available. When the
programmable schedule is turned off, only the Room setting
is available.
Indoor Sensor Not Installed
When an indoor sensor is not connected to the control, the
Room setting operates as a parallel shift of the heating curve.
This allows fine tuning of the heating system. If the Room set-
ting is set above the Indoor Design setting, the entire heating
curve is shifted higher, resulting in longer heat on times being
calculated. Similarly, if the Room setting is set below the Indoor
Design setting, the entire heating curve is shifted lower, resulting
in shorter heat on times being calculated.
Indoor Sensor
Installation of an optional Indoor Sensor will provide better
temperature control compared to no indoor sensor installations.
When installed, the control automatically adjusts the heating
curve up or down to so that the ambient air temperature
reaches the Room Target. If the ambient temperature exceeds
the Room Target by 1°F (0.5°C), the control sets the Heat On
time to zero and turns off the steam boilers.
Indoor Sensor Options
The control is compatible with indoor sensor models 076, 077
and 084.
The temperature accuracy within the building can be improved
by installing a square number (4, 9, 16, 25) of sensors wired in
series-parallel to the auxiliary sensor input.
-
10%
-
0%
0 (°F)102030405060
Boiler Cycled
On/Off
Boiler On 100% of Heating Cycle
Boiler On 100% of Heating Cycle
Percent On Time Per Heating Cycle
Outdoor Air Temperature
70
A = Outdoor Start
B = Boiler Start %
C = Outdoor Design
D = Boiler Design %
-
20%
-
30%
-
40%
-
50%
-
60%
-
70%
-
80%
-
90%
C, D
A, B
-
10%
-
0%
0 (°F)10
75%
65%
42%
2030405060
Percent On Time Per Heating Cycle
Outdoor Air Temperature
70
-
20%
-
30%
-
40%
-
50%
-
60%
-
70%
-
80%
-
90%
Room @ 70°F
Room @ 55°F
Room @ 75°F
Indoor Sensors 084, 077 and 076
To Indoor Sensor Input
Series - Parallel
Wiring
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