A gas or electric tankless hot water heater differs from the traditional hot water heater as it is designed to heat water on demand as opposed to the traditional hot water heater which stores the water in a tank continuously using either gas or electricity to keep the water hot.

With the tankless heater, when the tap for hot water is turned on cool water passes through the pipe that is connected to the unit which immediately heats the water passing it directly through the tap without the need for storage.

When purchasing a gas or electric tankless hot water heater you will have to consider the amount of demand for hot water in your home as these can pump from two to five gallons per minute but do not store any water which can become a problem if you require a larger demand.

However, for large households with simultaneous usage you have the option of purchasing multiple units which can be installed for an individual room such as a laundry room or you can purchase a "whole house" tankless heater which can be relatively expensive, but have a higher "GPM" or "gallons per minute flow rate."

If you are interested in purchasing a gas or electric tankless hot water heater, you can browse internet websites such as Amazon.com and check out the different styles and models to find the one that is right for your home.