Professor POU/POE – April 2013

April 1, 2013

Q I have an industrial customer that, in my opinion, has made a real mess of a triple softener system that I sold several years …


I have an industrial customer that, in my opinion, has made a real mess of a triple softener system that I sold several years ago. The original system had three 42-inch diameter tanks, each with its own water meter. Upon regeneration of any unit, the other two were prevented from regenerating but stayed online. This worked very well as long as the meters were all set to allow for enough capacity in case a unit had to wait, while another was regenerating.

The customer has converted the system into a duplex with one water meter initiating regeneration of unit number one. There is no provision made for initiating unit two. I believe it is being done manually. The original regeneration timer of unit two has been replaced by one from a different manufacturer, which is electronic and operates on low voltage (unit one’s timer is high voltage). 

Now the customer has come to us for help because neither unit, nor both units together, have enough capacity to last one full working day. They want both units to function together as a “system.”  I’m thinking, since they can function on one softener at a time, I could modify the system to regenerate more than once per day, but I don’t know how to do this automatically. Since the water use is very consistent throughout the work day, can I eliminate the water meter and strictly make the whole system work on a timer that initiates regeneration more than once per day?         

How can I accomplish this?

                                                                                                          – Wisconsin


What you need is very doable but I’m not sure I can give you every detail involved. You have asked two different questions. Can you make the two units work as a “system,” and can you regenerate them more than once per day, as a “system” based on time online?

Since timer number one is designed to receive a meter signal, it would be efficacious to keep it and make it work with timer number two also. We had email discussions wherein you did not think the two timers could be compatible because of the different voltages. Timer number one receives a signal from the water meter and initiates regeneration. It then controls the times of the various regeneration cycles by using a 120 minute “program wheel.” This has pins inserted into it, which determine how long a cycle lasts. The wheel rotates and when a set of pins comes into contact with a front-installed “micro switch,” the switch closes and an electrical signal causes the next regeneration cycle to begin.

The timer may already have another micro switch that was originally used as part of the lockout feature (often referred to as an interlock). If not, you can install one. We’ll call it the regeneration switch. Next, you need to install another pin on the program wheel that extends out the opposite side from the others. Spare pins are often furnished. The regeneration switch and the new pin can be set to engage at the end of unit one’s regeneration thereby initiating a regeneration of unit two.

The regeneration switch is called a “dry-contact” switch, which means it does not have power to it when assembled. Your unit might be wired from the previous interlock. It can be rewired with 120 volts found within the timer, or it can be fed with the low voltage power from unit two. Either way, the regeneration switch can send a signal to unit two in order to initiate a regeneration when unit one is done regenerating. In other words, the water meter can initiate a sequential regeneration of the two softeners. If you are feeding the unit one micro switch with 120 volts, you will need to install a relay with a 120 volt coil. Its “common” terminal will be fed with a low voltage matching that of unit two. Its “normally-open” terminal will carry the regeneration signal to unit two.

I do not think you need to convert to a timeclock unit, but, since you mentioned it, you could if you replaced the timer of unit one. There are timers that cycle more than once every 24 hours. You could obtain one that rotates every 12 hours, or more frequently. For this, disconnect the meter wiring. After the regeneration of unit one, a regeneration signal can be sent to unit two as was done above with the metered unit. A variation on this is to replace both timers with timeclock models that regenerate more frequently than every 24 hours. With this you have a simple system with each unit regenerating at different times of day, no meters and no interconnecting wiring.         

Two more problems need to be addressed. The original triple system must have had wiring, hopefully inside conduit, between the units in order to accomplish the lockout of two units, while one is regenerating. This must be disabled.

Unless you are very skilled at these things, you’ll still need engineering help and a good electrician. I recommend you start by contacting the manufacturer of the two timers or the company you buy industrial equipment from.


I thought I had seen somewhere in the past where the WQA said that water becomes corrosive at a pH of 6.3. I am having a hard time finding where I read that. And it seems like water can become corrosive at a higher pH than 6.3. Do you have any information pertaining to this? Do you know at what pH water becomes corrosive?


It is an oversimplification to choose one pH value and call it the corrosion point. In reality, different materials, or metals in this case, corrode at different pH values, and with other contributing factors. One has to look at each metal, or alloy, and find its chemical resistance properties. Then factor in all surrounding contributors to corrosion.

David M. Bauman, CWS-VI, CI, CCO, is technical editor of Water Technology® and a water treatment consultant in Manitowoc, Wis. He received his B.A. from the University of Illinois in Industrial Design. He can be reached by email at: [email protected].

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