Technical data

19 Installation, use and Maintenance manual - ed. 04/14
Inlet valves V1 and V2 are alternated in this way to validate their operation. If either one
fails then the water will rise to the Very High Level which will result in an alarm condition
and the other valve will close. This gives a high degree of protection from over-flow.
This cycle continues according to the dip switch 2, 3&4 settings. When the set point is
reached the water is then drained until Low Level probe is uncovered. When the low level
probe is uncovered the system then waits for 2 minutes and then runs the water for 6
seconds to drain to clean the sump... The drain then stays open for a further 20 seconds
and the recommence the fill cycle.
During drainage the scavenge pump is enabled. This scavenge pump is typically used in
the SDU internal cooler to pump away drain water where it impossible to use a gravity fed
drain.
The cooler drains down completely when stop or vent is selected. If low level probe is
covered during this then the drain valve opens and scavenge pump runs as described
above.
3.3.4 – External alarm
This contact must be made at all times. This can be used to stop the machine when linked
to:
Fire alarm system
Smoke detectors
3.3.5 – Timer
This switches the cooler on and off. This contact must be made at all times for the cooler
to run. The cooler will re-start at the previous settings.
3.3.6 – Humidistat
In automatic mode this disables the cool function and water circulation in Automatic mode.
This is typically used to limit the relative humidity in a building or to disable the cooling
when the external humidity exceeds a specified value
3.3.7 – Thermostat
In automatic mode the control system monitors the thermostat every 10 minutes. When
‘AUTO’ mode is selected, the cooler starts at speed 3 in cool mode. The thermostat
contact is the monitored. If the thermostat shows a closed contact then the cooler will
increase the speed of the fan by one increment up to the maximum speed 5 with cool. If
the thermostat shows an open contact, then the cooler will decrease the speed of the fan
by one increment until it either stays at VENT/Speed 1 or shuts down completely.
Note the OFF/OFF status is only enabled by using dip switch 8. Default is the cooler will
slow down to a minimum of VENT/Speed