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Fan Coil Actuator FCA 2
6 Appendix
6.1 Monitoring of actuating value
6.1.1 Application
Should the external room thermostat (RTR) fail, despite the last sent actuating value being 0%,
all valves remain closed, irrespective of the continued temperature characteristic curve.
This might lead to significant damages, e.g. if cold air enters the room in case of outdoor
temperatures below zero.
To avoid this situation, FCA 2 can ensure the following functions:
1. monitoring the proper functioning of the room thermostat
2. starting an emergency program in case of actuating value loss
3. sending the status of the actuating value monitoring
6.1.2 Principle
FCA 2 monitors whether, within the configured time value, at least 1 actuating value telegram is
received, and assumes a predefined setpoint in case actuating value loss.
6.1.3 In practice
The room thermostat is configured for the cyclical transmission of the actuating value.
On the FCA 2, the monitoring time is set to a value that is at least twice the cycle time of the
room thermostat.
If the room thermostat transmits an actuating value every 15 minutes, the monitoring time must
be at least 30 minutes.
After an actuating value loss, normal operation is resumed as soon as a new actuating value is
received.
If the block function is activated (object 1: Block heating = 1 or Enable cooling = 0), only the
actuating value loss telegram will be transmitted.
The relevant valve remains/is closed and assumes the configured emergency program actuating
value once the block is removed.
Updated: Feb-16 (subject to changes)
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