Tankless water heaters, or as others name them, demand-type water heaters, as their name suggests provide hot water on your demand only. They are designed in such way to  not waste energy that classic water heaters are used to do when producing the standby energy that get lost because of storing it without use. This is what arose the interest of many consumers to turn to this type of waters heaters as they allow them to cut their bill and therefore save their money. In this post I will try to provide you with some basic concepts about how they work, so that you get a clearer idea and decide if a tankless water heater is what your home needs and what to look for when choosing one of these units.

How Does A Tankless Water Heater Work

A tankless water heater heats water without going through a storage tank. Regardless of the type of element that heats the water (gas or electricity), directly after the water tap is turned on, cold water goes through a pipe into the unit. This system is what allows the owner to have a constant supply of hot water on demand. This is different from the classic scenario where your have to wait for the unit’s storage tank to fill up with the needed hot water. It is however important to know that a tankless water heater also has a limit and which differ depending on the brand and model. This limit can be found under the name of flow rate in the features list in the products info. Check this guide to pick the right one for your home.

A tankless water heater normally provide hot water at a rate of 2 to 5 gallons per minute, which is equivalent to 7.6 to 15.2 liters. According to energy.gov, electric tankless water heaters produce lower flow rates than gas-fired ones. This doesn’t mean that a gas-fired unit is able to always supply enough hot water when used simultaneously, in other words when you use the supplied water in different areas of the house. For instance, when you’re using the dishwasher and taking a shower at the same time, the water heater is used to its maximum and can easily reach its limit of hot water supply. The logical solution is of course to install another or other tankless water heaters and to connect them together to have a simultaneous supply of water.

One of the recognized advantages of having using a tankless water heater is their energy efficiency. For example, a home that use 41 gallons or less of hot water on a daily basis, using such water heaters can ben 24 to 34 percent more energy efficient compared to the classic storage water heaters (using a tank). For homes that use more than 41 gallons, like 85 gallons daily, tankless water heaters can be 8 to 14 percent more energy efficient. There are also other setups that can allow you to save more money like for example installing a tankless water heater at each hot water outlet.


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