CH250 ORP/pH Digital Controller - CHEMTROL

CH250 OPERATION

The CHEMTROL® 250 ORP/pH Digital Controller automatically maintains both sanitizer ORP (oxidation-reduction potential or Redox) and water pH in pools and spas.

All operating functions are clearly labeled and accessible from the front panel, with many safety and easy-reset features not found on other controllers:

• pH calibration from 4 to 10
• ORP setpoint from 400 to 900 mV
• pH setpoint from 4 to 10
• ORP and pH feed modes: off, manual, automatic
• ORP and pH proportional control bandwidth from 0 to 100% of the setpoint
• ORP high and low alarms from 400 to 900 mV
• pH high and low alarms from 4 to 10
• ORP overfeed safety timer from 0 to 999 minutes
• pH overfeed safety timer from 0 to 99 minutes

To select a function, simply press ORP or pH and then the desired function.  The display shows the current function value.  Use the UP or DOWN arrows to adjust to the desired value.

CONTROL SETPOINTS

The standard factory-set ORP control level is 700 mV, based on WORLD HEALTH ORGANIZATION (WHO)  values for prevention of germs and bacteria.

The standard factory-set pH control level is 7.5. Below 7.4, the water causes eye irritation and corrosion of equipment. Above 7.6, it also causes eye irritation plus water cloudiness, scaling, stains and reduced sanitizer efficiency.

To change the control levels, the operator presses ORP or pH and then SETPOINT. Use the UP or DOWN arrows to adjust the ORP and pH setpoints. To save the new setpoint value and exit, press SETPOINT again.

The controller then automatically activates the chemical feeders for sanitizer and acid (or soda) feed, as required to maintain the set ORP and pH levels – regardless of fluctuations in bather load, contamination and weather.  Like a thermostat maintaining a constant temperature, it prevents overfeeding or underfeeding, both of which are detrimental to good water quality.

ALARMS

When there is an alarm condition, the corresponding display flashes the alarm value:

• ORP out-of-range
• pH out-of-range
• ORP overfeed
• pH overfeed

The display stops flashing when the condition is corrected. To reset the overfeed timers, turn the feed mode to off and then back to Manual or Auto.

RESET

The ideal values are set as default values.  They can be adjusted by the operator at any time.  To reset all factory default values, press ORP and pH for 5 seconds.