By E. Allan Horner, CWS-III

For years, water softener control valves and media manufacturers have been pushed by customers and legislation to achieve greater water and salt efficiency. Electronic controls, variable reserves, meters, lower salt settings and aggressive training on how to make all of these advances work while still providing long media life and customer satisfaction has been very successful in achieving this important goal. Some advances created improved efficiency; others created more problems. Lately, gains in efficiency have been almost insignificant. We have started to hit the practical limits of a water softener’s salt efficiency. While some designs are more efficient that others, real savings have yet to be realized. Until a truly effective salt-free technology or a completely new design in water softening is invented, we need to start looking for ways to make bigger steps in efficiency. Many municipalities push customers with rebates to purchase highly energy-efficient, tankless water heaters, but then discourage them from also purchasing a softener, the simplest and most effective way to ensure this appliance does not quickly become a landfill candidate. Efficiency decreases rapidly with even small amounts of scale buildup, due to the heat exchanger’s inability to transfer heat to the water. Total system failure is common when these systems are not maintained properly.

Hot versus cold installation
During a recent technical phone call, I was asked how to make a homeowner more satisfied with a softener system that could only be installed on the hot water side due to plumbing limitations. I advised the caller to lower the hot water heater temperature, thereby forcing the homeowner to use more hot water in the shower, where they would feel the soft water.

Installing a softener to hot water only may sound new, but it is common practice in most commercial and industrial applications. Softeners that feed cold water applications are relatively uncommon and are usually only done when the water quality re- quires it for a particular application. Hot-water-only installations are common in restaurants, hotels, hospitals and manufacturing plants. Protection and efficiency of water heating equipment and applications that are sensitive to hardness minerals are the primary concerns. Specialized equipment that requires softened water (such as espresso machines or steamers) usually has its own small water softener, so salt consumption and the associated costs can be kept to a minimum.

The advantages of hot-water-only installations in residential applications that have a tankless water heater are numerous:

  • Up to 65-percent reduction in wastewater and salt consumption
  • Smaller equipment requirements
  • Typically easier installations temperature (106°F [41.1°C])
  • Additional equipment sales for whole-house treatment
  • Acceptance of water softener by municipalities that have already banned, or plan to ban, salt-based water softeners

Some disadvantages are apparent in some applications:

  • Installation of recommended remote temperature keypads adds to initial cost.
  • Toilets and other cold-water applications remain untreated.Further whole-house water treatment may still be neededfor iron or other contaminant removal that can be done withproperly designed multiple media systems.

I decided to start experimenting at my own house by replacing my 10-year-old tank water heater with a new tankless water heater. I installed flow meters with totalizers on the main feed to the house where my softener is installed, and a totalizing meter on the inlet side of the tankless water heater. I purchased remote keypads for the tankless water heater and installed them throughout the house, so the hot water temperature could easily be adjusted anytime. The basic premise was to find out if a residential hot-water-only installation could satisfy a homeowner’s desire for soft water, what problems could arise from this type of installation and most importantly, how much savings could be achieved.

Test center, complete with wastewater TDS monitoring, brine diversion, pressure monitoring, temperature monitoring, etc.


The results have far exceeded my expectations. Existing studies have shown conclusively that for a tankless water heater to remain efficient, scaling must be minimized or eliminated. Anti-scaling medias, polyphosphate filter systems and other technologies have fallen short on eliminating scale in heat exchanger systems like tankless water heaters. The sudden massive rise in temperature creates a condition that is ideal for precipitation of hardness miner- als scaling to occur. Water softeners have been proven to effectively eliminate these problems, thus maintaining heat exchanger efficiency.

After the remote keypads for the tankless water heater were installed, my family started using the water as if the water softener were installed to the hot water only. (This has proved to be much easier and nicer than expected.) The initial set point of the tankless water heater was 120°F (48.8°C). For this test, it was changed to 106°F, which has been surprisingly beneficial for showers and baths; the right temperature is achieved every time. This lower temperature creates a safer home for children and the elderly; it has nearly zero potential to burn or even irritate skin. Household dishwashers, which use a very small amount of water and are fed with hot water, are not affected by the lower temperature. These appliances heat the water to the proper temperature, regardless of the temperature of incoming water.

Tankless heater installed with totalizer and temperature confirmation monitoring.

By rethinking ways to make water softeners more efficient, we often overlook the obvious. The installation of tankless water heaters can open up new channels of business. Partnering with water heater installation companies or acquiring the knowledge, training and licensing to install and maintain tankless heaters yourself can help to expand business into new fields. The rapid growth of tankless water heaters gives us a new chance at increasing efficiency by simply reducing how much soft water we really need. And, as water softener brine discharge becomes more of an issue, our industry needs to preemptively do what is necessary.

Impressive results
Is soft water critical for the rinse water in residential laundry? Probably not, so a hot-water wash and cold rinse should be satisfactory for most customers. Soft water to the laundry can be achieved through different ways. In my own application, a cold soft-water-feed was plumbed due to close proximity to the water heater. Using a warm-water wash and rinse and simply turning off the cold water feed to the laundry also worked well in my testing. The final water consumption results after a month of testing were impressive. Approximately 35 percent of water use went through the tankless heater under these test procedures. This could result in a savings of 65 percent of salt consumption by a traditional water softener installation and an equal savings in regeneration. Installations are typically less expensive, and the equipment sizing could be considerably smaller.

About the author
E. Allan Horner, CWS-III, is Technical Director of PureGen Technology, Inc. He has been involved with pharmaceutical, commercial, industrial and residential water treatment since 1988, and has been a strong advocate for greater efficiency in all aspects of the water treatment industry. Previously, Horner was Research and Development Coordinator for a large commercial/industrial water softening company, and spent eight years with USP27 water systems. He has extensive experience in residential to heavy industrial water treatment systems, including specialty water-problem system designs. Horner travels extensively, conducting training seminars on green technologies, system application and maintenance. His next seminar is June 25th in Chino CA. He can be reached via email, or call (909) 548-0339.


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