Water Heater 101 Tank Vs Tankless Pros and Cons

Episode 10:  Water Heater 101 Tank Vs Tankless Pros and Cons.

Tankless water heaters, also known as demand-type or instantaneous water heaters, provide hot water only as it is needed. They don't produce the standby energy losses associated with storage water heaters, which can save money.

Tankless water heaters heat water instantaneously without the use of a storage tank. When a hot water faucet is turned on, cold water flows through a heat exchanger in the unit, and either a natural gas burner or an electric element heats the water. As a result, tankless water heaters deliver a constant supply of hot water. You don't need to wait for a storage tank to fill up with enough hot water. However, a tankless water heater's output limits the flow rate.

For homes that use 41 gallons or less of hot water daily, demand water heaters can be 24%–34% more energy efficient than conventional storage tank water heaters. They can be 8%–14% more energy efficient for homes that use a lot of hot water -- around 86 gallons per day. In some cases you may be able to achieve even greater energy savings if you install a demand water heater at each hot water outlet. 

The initial cost of a tankless water heater is greater than that of a conventional storage water heater, but tankless water heaters will typically last longer and have lower operating and energy costs, which could offset their higher purchase price. Most tankless water heaters have a life expectancy of more than 20 years. They also have easily replaceable parts that may extend their life by many more years. In contrast, storage water heaters last 10–15 years.

Tankless water heaters avoid the standby heat losses associated with storage water heaters. However, although gas-fired tankless water heaters tend to have higher flow rates than electric ones, they can waste energy if they have a pilot light. This can sometimes offset the elimination of standby energy losses when compared to a storage water heater. In a gas-fired storage water heater, the pilot light heats the water in the tank so the energy isn't wasted.

The cost of operating a pilot light in a tankless water heater varies from model to model. Review the manufacturer's literature to determine how much gas the pilot light uses