Tankless Water Heaters and Water Quality
Up until recent times, the primary choice for consumers have been the standard tank style water heaters. There is no argument that 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 a 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. Most manufacturers just recommend to the customer to install a water treatment device such as 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.
A more proactive approach that some in the industry have taken is educating their distributors and installers to know water quality in tankless installations and make recommendations to their customers when water treatment is needed, rather than telling them to find their own once the water heater needs service. In many cases, the application of a water softener is not an option due to the location of the water line, government restrictions, or customer bias leaving the tankless heater unprotected from mineral scale build up.