Tankless water heaters and water quality

Up until recent times, the primary choice for consumers have been the standard tank style water heaters.  Compared to tankless water heaters, standard tank style heaters are much less efficient in the heating of water. There is one advantage tank style water heaters have over the relatively new tankless technology, that is their ability to continue providing hot water in high water hardness conditions. Even with considerable amount of mineral scale deposits, traditional tank style heaters will continue to heat water until the desired temperature is reached, despite the fact that the process is even more wasteful of energy when mineral deposits are present.

Tankless water heaters provide instantaneous heating of water and even moderate scale build up on heat transfer surfaces greatly diminish their efficiency thus requiring frequent deliming service in hard water applications. This is most evident in applications where a tank style system is replaced by a tankless water heater in hard water areas. Prior to replacing the tank style water heater, the home owner may have never had to replace elements or maintain the heater for problems caused by hard water mineral deposits.

Their tank style heater continued to work inefficiently, but still provided hot water. Once they replaced the tank style heater with a tankless heater, they found much to their surprise the need for periodic deliming. Tankless water heaters are much superior to tank style heaters in all aspects except water quality forgiveness. Many manufacturers and installers recommend the customer install a water softener.

Keep in mind that for various reasons, the customer did not feel the need to have a softener during the time that they did not have a tankless water heater. Now in order to solve mineral scale issues, they are required to purchase a water softener.

In some instances in moderate hardness applications, small amounts of scale will form in the tankless heaters and then break off in small pieces from the expansion and contraction of the heat exchanger during heating and cooling. The small bits of scale can cause shower heads and faucet strainers to plug periodically causing a maintenance headache.

Adding a water softener requires access to a drain, electrical plug, space, and usually ends up costing more than the tankless heater.

This is why HydroBlend/ScaleStick systems are the answer. These low-cost units can be applied anywhere along the water line feeding the tankless heater (right next to the heater or on the whole house). No need to add salt, just replace the cartridge on average once per year and the tankless water heater will be protected from mineral scale deposits.

SFES Tankless Heater Systems protects equipment by the following process

HydroBlend® media sequesters (binds) with scale-causing minerals making them more soluble in water thus reducing the chances of precipitation as hard mineral scale.

In the event that scale causing minerals do precipitate out of solution, SFES systems prevent mineral scale accumulation by distorting the shape of the scale crystal so that it cannot build up on itself. 

By combining with scale-causing minerals, SFES systems provide corrosion control by forming a protective micro-thin glass-like lining on wetted surfaces acting as a deterrent to corrosion and scale.

Overtime, SFES systems will also help soften and remove existing mineral scale deposits.


SFES Tankless Water Treatment Systems utilize HydroBlend®, effectively controlling mineral scale deposits on heat exchangers in tankless water heaters. HydroBlend® is specifically formulated to work in high-temperature / high-hardness environments providing unparalleled mineral scale prevention and corrosion control.

SFES Tankless Water Treatment Systems utilize a high pressure clear filter housing that is rated 125 psi for placement on the cold water line feeding the tankless water heater. This allows a simple glance at the housing to determine when the ScaleStick® cartridge is depleted.

The Standard PF-10 SS Systems must be installed on the cold water inlet line feeding the tankless heater. If there is a recirculation line feeding hot water to the inlet connections, use the High Temp ScaleStick Systems if the water line is hot. The Standard PF-10 SS Systems may be installed if there is a recirculating loop as long as it is installed outside the loop on the cold water inlet water line.

Standard PF-10 SS Systems

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High Temp ScaleStick Systems

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SFES Tankless Water Treatment Systems are offered in three cartridge sizes allowing for application on single or multiple units depending on water flow rates and usage characteristics.

ScaleStick® cartridges fit standard 10″ filter housings allowing them to be used with any number of standard housings that accept 10" filter cartridges in new or existing applications.


For use on a single tankless heater with an average continuous flow rate of 1-3 gpm.


For use on a single or twin tankless heater(s) with an average continuous flow rate of 2-4 gpm.


For use on a single or twin tankless heater(s) with an average continuous flow rate of 3-6 gpm.

Note: The average continuous flow is an estimate of the average flow the tankless unit will be heating. Maximum flow rates through the treatment system are approximately 12 gpm depending on incoming water pressure. This applies to all of the treatment systems for tankless heaters.