3
How a Duro Automatic Backwashing Filter Works
In normal operation, the Time of Day display will alternate being viewed with the Day Remaining display. As day passes,
the day remaining will count down from a maximum value to zero or (---). Once this occurs, a regeneration cycle will be
initiated at the Set Regeneration Time. Water flow through the valve is indicated by the Flow Indicator that will flash in direct
relationship to flow rate.
Example
3 Days Remaining
to Regenerate
0 Days Treated
Water
Remaining
Timer Behavior During Regeneration
In regeneration, the control will display a special regeneration display. In this display, the control will show the current
regeneration step abbreviation the valve is advancing to or has reached and the time remaining in that step. The step
abbreviation displayed will flash until the valve has completed driving into this regeneration step position. Once all
regeneration steps have been completed, the valve will return to Service and resume normal operation.
Example
Less than 6 minutes
remaining in Regeneration
Step Rapid Rinse
Pushing the
during a regeneration cycle will immediately advance the valve to the next cycle step position and
resume normal step timing.
Please see the control valve manual for different regeneration step abbreviations.
PM Indicator
PM Indicator
Flow Indicator
(Flashing with water flow)
Flow Indicator
(Flashing with water flow)
5
Regeneration Step
Abbreviation
The chemical free iron filter consists of two major components which are:
1. A hydrocharger, located between the well head and the pressure tank, adds a small amount of air to the iron-laden
water whenever the well pump runs. Refer to Figs. 1, 2 or 3 on Page 8 for its location.
NOTE:
If your pump system is a constant pressure or variable frequency drive (VFD) the hydrocharger supplied with
this filter will not operate properly. The system will require the addition of an air pump and vent tank to intro-
duce the needed air into the water system. Refer to page 8 for more information.
2. A backwashing type filter containing special media that causes the iron in the “hydrocharged” water to precipitate
throughout the filter bed (rather than on the surface as in chemical oxidizing filters). This process produces an iron removal
capacity of up to 30,000 ppm. The media requires no chemical regenerant for oxygen enrichment. Your filter automati-
cally adjusts the pH to neutral or higher on acid water without an acid neutralizer. The ability to raise pH when it is below
neutral (7.0 or less) greatly enhances the filter’s ability to remove iron efficiently. The clean, filtered water then flows into
your household water line. Depending on water use and the concentration of iron in your water, periodic backwashing is
required to flush the entrapped iron from the system. The filter control can be programmed to backwash once every two,
three, four, six or twelve days as required (instructions for calculating backwash frequency and setting the controls are on
Pages 20 and 25).
NOTE:
Replenishment of the media that raises pH will be required periodically, depending on how low the raw water
pH is, the amount of manganese (Mn) present in the water and the water usage rate.
