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• An owner's guide to tankless water heaters - hot water on demand
• Tankless water heaters = demand water heaters = instantaneous water heaters
• Detailed explanation of how tankless hot water heaters work, what they cost, what are their operating characteristics, pro's and con's.

Here we discuss the conversion from conventional hot water heaters to use of tankless water heaters, also called instant water heaters or "on demand" water heaters. Readers should also see ALTERNATIVE HOT WATER SOURCES to distinguish among these types of hot water producing systems.

The original text of this article was provided courtesy of Carson Dunlop - that text has been edited and may not entirely reflect CD's views. Page top sketch of a point of use tankless water heater courtesy of Carson Dunlop. Our OPINION is that readers looking for plenty of hot water heated efficiently should also consider the heater we describe at Indirect-fired Water Heaters.

© Copyright 2009 Daniel Friedman & Carson Dunlop Associates, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

Should I Convert my Hot Water Supply to a Tankless Water Heater?

OPINION:

Most of us are familiar with the traditional-style water heater - that big thirty- to sixty-gallon tank taking up space in the basement near the furnace or boiler. These water heaters have served us well with few improvements for decades, but a different breed of water heater has been in use for many decades in Europe and Latin America, and has seen less widespread but growing popularity in the U.S. - the tankless water heater.

The energy-conscious world in which we live has turned its attention to the water heaters of old and has identified two potential areas of improvement. The first is that traditional water heaters are not very efficient at converting the energy in fossil fuels into hot water. Over the last twenty years, furnace and boiler technology has improved the efficiency of home heating, but water heaters have not kept pace, even though the same technology can be applied.

The second possible improvement that can be made to water heaters has to do with the storage of hot water. Traditional water heaters use fuel to heat water inside the tank. If the water is not used, it cools to the point that it must be heated up again.

The result is that we are constantly keeping a large volume of water at a high temperature, even if we are not planning on using any of it in the next little while. This means that while we are sleeping or at work, our water heaters are burning fuel or consuming electricity keeping a whole tank of water hot.

This is not a problem in the winter, when the heat loss from the water heater helps keep the building warm. It is a challenge in the summer, when the building is already warmer than we want. Tank-type water heaters can increase air conditioning costs.

As the name suggests, tankless water heaters have no tank, and therefore no storage capacity at all. When the faucets and fixtures in the home are sitting unused, the water heater is dormant. When somebody turns on a hot water faucet, the tankless heater swings into action.

These units use more powerful burners than conventional water heaters to heat relatively small amounts of water. The result is that the water is heated much more quickly than in an older system and this hot water can be immediately delivered to the fixtures.

A significant advantage of this system is that you can't empty all of the hot water out of the tank because there is no tank - just continuous hot water.

Also, since there is no tank, the water heater itself is much smaller. In most cases, these units are wall-mounted, so we not only do we have improved efficiency, reduced fuel costs, and unlimited hot water, but more free space in our basements!

While this all sounds good so far, there is a reason that everybody isn't switching over right away.

Conventional water heaters, due to their simplicity, are relatively inexpensive, while tankless water heaters are more expensive to purchase.

Their complexity also means that maintenance and repairs can be more expensive as well, and while tankless units have been in use around the world for many years, the rapidly evolving technology and our cold climate means that we don't have a great idea how long the typical life expectancy will be in North American homes.

Still, when it comes time to change your water heater, consider getting rid of that big tank and going tankless.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

  Tankless Water Heaters
    Guide to Tankless Water Heaters
    Operation & Characteristics
    Problems & Defects
    Hot Water Delivery Speedup
    Installation Requirements & Costs
    Should I Convert to a Tankless Heater?
    Calculate Water Heater Requirements
    Capacities of Tankless Water Heaters
    Life Expectancy & Applications

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Consumer Reports offers an article on the efficiency versus the economy of tankless water heaters - see http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm
• Bosch Tankless Water Heaters - http://www.boschhotwater.com/
• Chromolite Tankless Water Heaters
• Bradford White Everhot Tankless Water Heaters - Bradford White offers this step by step hot water retrofit installation file (large, slow PDF) - www.bradfordwhite.com
• Eemax Tankless Water Heaters - http://www.eemaxinc.com/
• Noritz Tankless Water Heaters - http://www.noritz.com/
• Rheem Tankless Water Heaters - http://www.rheemtankless.com/content/
• Rinnai Tankless Water Heaters - http://www.rinnai.us/tankless-water-heaters/
• Stiebel Eltron Tankless Water Heaters - http://www.stiebel-eltron-usa.com/
• Takagi USA Tankless Water Heaters - http://www.takagi.com/
• Titan Tankless Water Heaters - http://www.titanheater.com/
• U.S. Department of Energy on Tankless Water Heaters - http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12820

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