Grant Instruments RC - Manual (Page 9)

Recirculating Chiller
Part No 09931/Issue 8 Page 9 August 2001
Figure 4
3.1 The controller
The controller (see Figure 4) is used to set the operating temperature, high and low temperature
alarm levels and to initiate the self tune routine. During operation the actual liquid temperature is
shown on the display. To view the set point, press and release the or button.
3.2 Temperature setting
To set the required operating temperature, press the or button until the required
temperature is displayed. Two seconds after releasing the button the new value will be accepted
and the display will revert to showing the actual temperature.
RC350G, RC400G and RC1400G control the liquid temperature by using a heater to balance the
effect of the cooling power. They can also be used as heated circulators to raise and control the
temperature of external equipment up to 60°C.
RC3000G controls temperature using a hot gas bypass system, which is effectively an on-off
control for the refrigeration system; this is highly energy efficient, but means that the RC3000G
can not be used for heating: the most stable performance is achieved when cooling a large
volume with a stable heat load.
3.3 Over- and undertemperature alarm setting
The overtemperature and undertemperature alarms are set as an offset from the operating
temperature, not as actual temperature values. For example, you might set the overtemperature
alarm to operate if the temperature rises more than 5°C above the operating temperature.
Once set, the alarm levels will follow the operating temperature, always maintaining the same
offset. This means that you don't have to reset the alarm levels each time the operating
temperature is changed. You can, of course, change the alarm offset levels at any time.
The alarms are blocked until the chiller has reached its operating temperature - they will not
operate during the initial cooling or heating phase.
These alarms are not safety devices; their only function is to attract attention.
If the alarms operate they will switch off when the temperature returns to within the offsets.
OP1
OP2
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Readout
Page
button Scroll
button Down
button Up
button
↓
Heater
‘ ’
Controller alarm
↑
↓ ↑