Page 11 of 26
Hydra 798 Iss.10 – 04/18
IMPORTANT READ THIS NOW!
CHILLERS
The M and L models include an internal mechanical refrigeration unit. During transit the internal oil can be displaced.
On arrival the equipment should be left for 24 hours in an upright position to allow any displaced oil to settle.
Chiller function - Medium
The chiller is designed to automatically enable at any temperature below 40°C. The chiller will run all the time and
the temperature control is balanced by the heater. The chiller will have unwanted cooling power at the higher
temperatures, such as temperatures above -10°C; it can cause unwanted instability in the liquid temperature. To
prevent this, the Hydra has an automatic cooling reduction facility built in. This is in the form of an internal by-pass
valve that will reduce the running pressure of the refrigeration system.
The by-pass valve will automatically enable at temperatures above -10°C until the chiller is automatically switched off
at 40°C. Because of the time taken to cool down from higher temperatures with the by-pass enabled and reduced
cooling, the by-pass valve only actually opens when the actual temperature is within ±3 °C of the set point. This
allows the full cooling at all other times.
The functions of the chiller can be identified by the display of the controller on the front panel. Refer to the
controller section on page 15 for details.
The diagram below gives a graphical account of the Hydra medium chiller function
(1)
Chiller enabled.
(2)
Full cooling, by-pass valve off
(3)
By-pass valve enabled
(4)
Band of temperature where by-pass
valve is active.
