Fujitsu Waterstage WS G140DC6 Series Maintenance Document page 7

Split system (Single phase and 3-phase type)
Faults external to the heat pump
Any safety device (e.g. thermostat pressure switch)
wired to input Ex3 (E20) allows external problems to
be reported and the heat pump to be immediately
Maintenance Document 1544-1
stopped. For example, a safety thermostat on the
heating floor can be wired to input Ex3 (E20) to avoid
excessively high temperatures in the floor.
Figure 1: Typical Wiring of External Devices
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