Service manual

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7.9.1 Parallel Piping
In parallel piping applications, the boiler outlet
temperature is typically the same as the system
temperature. Therefore the operating
temperature sensor is the boiler outlet sensor.
Figure 7: Parallel Piping
7.9.2 Primary / Secondary Piping
In primary / secondary applications, the boiler
outlet temperature is typically hotter than the
system supply temperature. This occurs as the
system supply pipe has a higher flow rate than
the boiler outlet pipe. Therefore, the control
requires a boiler outlet temperature sensor and
a system temperature sensor
Figure 8: Primary / Secondary Piping
Figure 9: Typical Heating System