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Building Technologies Division User Manual RWF50... CC1U7866en
Infrastructure & Cities Sector 5 Operating modes 25.07.2014
5 Operating modes
5.1 Low-fire operation
Low-fire operation means that only small amounts of heat are drawn from the boiler.
Using relay K1 Burner release, the 2-position controller ensures control to the setpoint
by switching the burner on and off like a thermostat.
This mode of control is known as the thermostat function. An adjustable switching
differential ensures that the burner’s switching frequency can be selected, aimed at
reducing wear.
ON
OFF
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Figure 6: Control sequence of heating controller
Modulating and 2-stage operation:
Actual value lies between switch-on
threshold HYS1 and switch-off threshold
HYS3.
If the controller is set to cooling mode, temperature limits HYS4 and HYS6 apply. In that
case, relay K1 Burner release is used for controlling the cooling equipment.
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ON
OFF
Figure 7: Control sequence of cooling controller
Modulating and 2-stage operation:
Actual value lies between switch-on
threshold HYS4 and switch-off threshold
HYS6.
Thermostat function
Heating controller
Cooling controller
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