IM-P403-89
EMM Issue 8
15
3. System overview
3.1 Function
The controller has an adjustable alarm and set point levels.
The product can be configured to control TDS / conductivity of water. Once fully commissioned,
the TDS value is displayed in μS / cm (or ppm if selected).
Note:
Conductivity is expressed in parts per million (ppm) or micro Siemens per centimetre
(µS / cm). Micro Siemens / centimetre is becoming the more common unit, and is therefore
the default setting.
If the water conductivity exceeds the set point level, 'BLOWDOWN' will be displayed and
valve relay will be energised until the conductivity drops below the set point level (plus a
hysteresis value).
The hysteresis setting is adjustable and provides a damping effect where water movement
at the probe may otherwise cause over-frequent switching of the blowdown or dump valve.
This could be caused, for example, by boiler firing rate variations, by the feedpump operating,
or by sudden changes in boiler load.
If the water conductivity exceeds the alarm level, 'HI ALARM' will be displayed and the alarm
relay will be de-energised until the conductivity drops below the alarm level (plus a hysteresis
value).
3.2 Inputs
The BC3250 can accept a signal from a Spirax Sarco conductivity probe (CP10, CP30 or
CP32) and a Pt100 temperature sensor.
A Pt100 temperature sensor may be connected to the controller to display the boiler water
temperature (
°C or °F) and provide temperature compensation (2% /
°C). This is
recommended if the boiler is working at varying pressures, or for other applications such as
condensate monitoring or coil boilers, where the temperature may vary.
If a Pt100 is not fitted, the boiler operating temperature can be entered.
The default temperature value is 184
°C @ 10 bar g.
Summary of Contents for BC3250
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