How Do Tankless Water Heaters Work

best-tankless-water-heater-213x300Tankless water-heating is a concept that is now quickly gaining popularity in the United States.

The technology has been widely used in countries like Japan for a long time and has already become popular in Europe.

Tankless water heaters, also sometimes called instant water heaters, don’t make use of a storage tank to store hot water. Instead, they provide an instant supply of hot water when required.

The working of a tankless water heater:

Tankless water heaters use a heat source fueled by electricity, gas or propane. The heat is transferred to the water as it flows through a heat exchanger inside the heater producing instant hot water. The heating system is only activated when the water enters the system and hence it does not operate until it is required. It can meet the hot water requirements of an entire house.


Storage water heaters use a large tank to store water. The heat source is then used to heat the water in the tank. The temperature of the water is kept at the desired level by a thermostat which switches on the heating source as required. This keeps the water in the tank at the required temperature.


  1. It heats up a lot of water even if there is no requirement for it resulting in wastage of energy.
  2. The stored water loses heat after some time and the energy source is activated to maintain the temperature. These cooling and reheating cycles result in even more energy wastage.
  3. It cannot supply hot water initially without some delay as it has to heat a large quantity of water. This delay depends on the heating source, the temperature of the water in the tank and the size of the tank. If a large tank is used, a long wait may be required especially during winter.
  4. If the amount of water used continuously is greater than the capacity of the tank, then it will not be able to supply water at the required temperature without delay. This can cause a lot of inconvenience if people have to pause in between say, a shower to wait for the water to heat up again.
  5. Storage water heaters are prone to corrosion over long periods resulting in shorter life.


  1. It produces instant hot water on demand. There is no need to wait.
  2. There is no wastage of energy. The energy source is activated only when there is a demand for hot water. Since no hot water is stored there is no wastage due to cooling or reheating. The savings in terms of energy bills could be as much as 10% to 20% when compared to storage heaters.
  3. The flow of hot water is continuous irrespective of the quantity of water used. There is no risk of running out of hot water while doing something.
  4. There is very little risk of corrosion as no water is stored. Tankless water heaters have a life of up to 20 years compared to a lifespan of 10 to 15 years of a storage water heater.

For homeowners who have a central storage water heater, changing over to a tankless water heater may look like a large investment. However, the savings in terms of energy bills, repairs and replacement costs will easily recover that amount during the life of the new heater.

For people who are installing a new water-heating system, it is best to go for a tankless water heating system. Choosing an energy efficient water heating system will be a wise decision that will be rewarding over time.

Leave a Reply

Your email address will not be published. Required fields are marked *