Fujitsu WATERSTAGE WS A050DD6 Series Maintenance Document page 6

Split system single 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
6
Figure 1: Location of DIP switches and diodes
on the hydraulic unit interface card
Figure 2: Typical Wiring of External Devices
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.
Maintenance Document 1589-3