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CB FALCON

750-265 28

Fig. 10. Outdoor reset parameters.

Steam Loop Demand and Rate

The CH (Central Heating) Steam Demand and Rate source

compares a selected input sensor to a setpoint.

Burner demand will exist if the sensor pressure falls below the

setpoint minus a hysteresis value. Once the burner demand

signal is on, it remains on until the sensor pressure is above

the setpoint plus a hysteresis value, or until the other selected

demand source input (e.g., Stat, Remote Stat) if any, turns off.

Pump (or output) demand may be driven by the selected

demand source input (Stat input, a remote stat, or by the

sensor alone).

A Proportional-Integral-Differential (PID) controller operates to

generate the demand source’s requested modulation rate.

The Steam Central Heating function is implemented as shown

in Fig. 11.

CH ODR Parameters LL ODR Parameters

Setpoint

TOD Setpoint

Minimum Outdoor Temp

Maximum Outdoor Temp

Minimum Water Temp

Boost Time

Boost step

Boost recovery step time

Boost Max Setpoint