Tankless Water Heaters: How They Function

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This article begins what I intend to be a long series of general, informational articles on tankless water heaters. Most of these will be written by guest bloggers, as this one is. I thought this article was a nice clear explanation. -- Lou

If you have ever given a long thought to the inefficiencies of tank-type water heaters, you must have figured out many including inefficient use of energy and space. Those who figured this out before you saw the demand for tankless type water heaters and brought them into the market quickly. Still, a large number of people are used to conventional water heaters and unaware of how tankless heaters can solve some of their problems. Let's see how the concept of on-demand heating was applied to get another remarkable invention of mankind.

The main concept behind these heaters is provision of hot water on demand only. There are different types and they can utilize natural gas, propane or even electricity to heat water. Since these heaters don't have a storage tank with them, they heat up water only when it is required. The main component is a heat exchanger that gets switched on whenever the connected faucet or shower is opened. For this purpose, a flow-activated switch is used that detects the flow of water inside the pipeline. Two types of heat exchangers are used usually: gas-powered burner and electric coils. Gas-fired ones, however, are able to heat faster and more efficiently.

Tankless heaters are available in different sizes and determination of the size depends on three main factors: the amount of water that has to be heated in one minute; the temperature of water when it goes into the heater; and lastly, its preferable temperature that you want at the outlet. Unlike tank-type storage heaters that keep water at the desired temperature using a thermostat, tankless heaters heat water on demand; so the initial flow of water that you get after opening the faucet gets warmer gradually and you might need to waste some cold water before you get hot water. The amount of time it takes to get hot water after opening the faucet is known as lag time. Two types of tankless systems are available. The first one is the point-of-use heater, which is generally small in size and is used to provide hot water at a single outlet like a shower. Since it is installed in close proximity to the water outlet, a point-of-use heater typically has a lower lag time and less water is wasted. Since it is used to supply hot water at a single outlet, electric-powered fire exchangers can do the job quite well. Hence, most point-of-use systems run on electricity and can be fitted inside a cabinet or closet due to their small size.

The second type, whole-house tankless water heater, is able to heat a significantly greater amount of water per minute and can cater hot water at various outlets simultaneously. Since they need more energy to heat up larger volumes, they typically run on propane or gas. For larger houses, you may need more than one whole-house system. Showers typically necessitate addition of another whole-house tankless system because they usually need more hot water than ordinary taps. Due to their extra capabilities, whole-house heaters cost a lot more than point-of-use systems.

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Scott Rodgers is a master plumber who has recently begun writing articles for both a plumbing and non-plumbing audience. To view more of plumbing articles, visit http://www.eLocalPlumbers.com

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