Tankless Hot Water Heaters

by Rachel Laurendeau on September 11, 2012

If it is time, or nearly time, to change your hot water heater, you may be interested in learning more about tankless water heaters, also called instantaneous or on-demand hot water heaters. These are an alternative to conventional hot water tanks and are worth looking into for certain applications.

How do tankless heaters work?
Tankless hot water heaters do not store hot water in reserve in a tank. Instead, the small, units (wall-mounted or under the vanity) heat water only as it is needed. The heaters use either a gas burner or electric element to heat cold water as it passes through the unit. Today, the electric units tend to use quite a lot of power so if you are looking for something more energy efficient, the gas type is a better option. Additionally, the electric units typically require 200 amp service, so an electrician may be required to install that service if your house does not yet have it.

Advantages
• You never run out of hot water – great for long showers!
• Tankless heaters have a longer lifespan than conventional heaters, up to 20 years.
• Tankless systems require much less space than large storage water heaters.
• They can be installed as the main water heater for your whole home or as add-ons for specific requirements such as hot tubs or bathrooms that are further away from your hot water tank.
• Their optimal use is for smaller application, such as vacation homes, campers, or houseboats. (Source: www.thisoldhouse.com)

Disadvantages
• It may be more difficult to find plumbers who are knowledgeable and experienced at installing or repairing tankless hot water heaters since they are newer and less common than hot water tanks.
• Tankless heaters are more expensive than conventional heaters.
• Although they only heat water on a demand basis, they do require a lot of energy to do so, meaning that they may not be the green alternative that they are often touted to be. The energy saved compared to a storage type heater will probably not show a pay-back on your initial investment for years, if it ever does. (The exception to this would be in a household that uses 41 gallons or less of hot water daily, according to www.energy.gov.)
• The amount of water that can be heated per minute is limited, so the system often can’t keep up with demand (slow flow-rate). This can be particularly problematic in a busy household where there may be multiple needs for hot water at once (i.e. dishwasher, shower, washing machine…)

There is still a certain amount of debate as to the amount of energy savings that can be achieved with a tankless hot water heater but as this innovative product becomes more efficient and some of the bugs get worked out, it will likely become more popular in American homes. Talk to your home improvement expert or a professional plumber for more information on choosing the right hot water heating system for your home.

Resource: This Old House and Green Building Advisor

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