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Tankless or On-Demand Water Heaters

Advantages & Disadvantages - Part 1

Part 2

If you are considering the installation of a tankless water heater, as shown in Figure 1, in your home you should be aware of the advantages and disadvantages of these types of water heaters.

tankless hot water unit
Figure 1 - Tankless hot water heater

Tankless water heaters have been used in Europe for over 50 years, it is only over the past 10 years that they have become popular in North America. Unlike conventional water heaters which have a tank that stores hot water which is always being heated to maintain its preset temperature. Tankless water heaters heat the water only when hot water is requested from a faucet. There is no pre-storage or the need for continuous heating of hot water.

Tankless, or as they are sometimes referred to as on-demand or instantaneous water heaters, are available for most of the common energy sources or fuels; NG, LP and electric. Most studies indicate that for an identical water demand, the gas fuels such as natural gas and liquid propane were more than 20% more efficient than electrical powered units with the same overall capacities and capabilities.

As with most things, nothing is perfect and there are advantages and disadvantages to both the traditional tank water heater systems as there are with tankless hot water systems. In order to decide which is best for your situation we have outlined the major advantages and disadvantages of a tankless hot water system.

Although it is possible and many people do retrofit a tankless hot water system into a home that currently uses a traditional hot water tank, in many cases the costs involved in retrofitting the new tankless hot water system are not economically justifiable.

Tankless Hot Water Systems:

There are two tankless hot water system configurations:

  1. Whole House System:
  2. As the name implies one tankless water heater is used to supply the hot water needs of the entire home. This type of tankless hot water system is a common retrofit as the unit can be installed in place of a currently installed traditional hot water storage tank.

traditional hot water system
Figure 2 - Traditional hot water system using a hot water tank
whole house tankless hot water system
Figure 3 - Whole house tankless hot water system