Tankless water heaters have been around for several decades now. Europe and Japan were the innovators and early adopters of this new technology.

Tankless Water Heaters

Tankless Water HeaterTankless water heaters offer on-demand heating which means you only pay to heat when hot water is called for in the system. This helps reduce your energy cost and extends the life of tankless water heaters beyond that of common tank water heaters.

Benefits of Tankless Water Heaters

The #1 benefit is endless hot water volume -you will not run out of hot water. This is especially beneficial to larger families who take concurrent showers.

Reduced size means more storage space for you. A conventional storage tank water heater can take up to five times the space of a tankless. Usually the tankless is installed on an exterior wall or several feet off the ground. This frees up floor space for you to use for other purposes. Let Champion Plumbing & Drain Cleaning in Canton, GA show you the best options for installing a tankless waster heater to maximize the floor space in your home.

Sizing a Tankless Water Heater for Your Home

How A Tankless Water Heater WorksFirst, list the number of hot water devices you expect to use at any one time. Then, add up their flow rates (gallons per minute). This is the desired flow rate you’ll want for the on-demand water heater. For example, let’s say you expect to simultaneously run a hot water faucet with a flow rate of 0.75 gallons per minute and a shower head with a flow rate of 2.5 gallons per minute. The flow rate through the on-demand water heater would need to be at least 3.25 gallons per minute. If you want to reduce flow rates, we can install low-flow water fixtures.

Tankless water heaters are rated by the maximum temperature rise possible at a given flow rate. Therefore, to size an on-demand water heater, you need to determine the flow rate and the temperature rise you’ll need for its application (whole house or a remote application, such as just a bathroom) in your residence.

To determine temperature rise, subtract the incoming water temperature from the desired output temperature. Unless you know otherwise, assume that the incoming water temperature is 50ºF (10ºC). For most uses, you’ll want your water heated to 120ºF (49ºC). In this example, you’d need an on-demand water heater that produces a temperature rise of 70ºF (39ºC) for most uses. For dishwashers without internal heaters, and other applications, you might want your water heated to 140ºF (60ºC). In that case, you’ll need a temperature rise of 90ºF (50ºC).

Most on-demand water heaters are rated for a variety of inlet temperatures. Typically, a 70ºF (39ºC) water temperature rise is possible at a flow rate of 5 gallons per minute through gas-fired on-demand water heaters and 2 gallons per minute through electric ones. Faster flow rates or cooler inlet temperatures can sometimes reduce the water temperature at the most distant faucet. Some types of tankless water heaters are thermostatically controlled. In other words, they can vary their output temperature according to the water flow rate and inlet temperature.

Things to Consider About Tankless Water Heaters

The ”cold water sandwich” refers to the brief moment of cold water only during a shower. Not a pleasant experience and thankfully many Tankless water heater manufactures have made fixing this a priority. Tankless water heaters have a minimum flow rate and could trigger the dreaded “Cold water sandwich”. This is when the flow rate or output of the fixture being used (typically a shower) drops below the rated minimum threshold of the tankless. The tankless is then tricked into turning off for a brief moment until it recognizes the proper flow rate and re-fires.

You need to have the tankless water heater flushed annually. This involves hooking a transfer pump up to the tankless and inducing a vinegar solution. This helps de-lime and removes the scale out of the unit. These contaminates prohibit your tankless from operating at peak efficiency. This is usually done by a licensed Plumber, as they have the tools and understanding of how to perform this properly.

Some consumers have reported a lower flow rate when using tankless water heaters. This is most likely due to the reduction in tubing size within the heat exchanger.


Do you have questions about water heaters? We’ve got answers! Join our Facebook group Plumbing Questions and Answers, or check out our page About Plumbing. If you want to learn how to properly maintain your water heater read our article about Water Heater Maintenance. Feel free to call us at 770-480-5077.