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What Is a Tankless Water Heater and How to Install One


Water heaters are something you probably don’t think about until you need to replace one. Depending on how old your water heater is, you may not be able to get the same model you had—or even want to. Upgrades in design and energy efficiency have changed the options on the water heating market. A buying a tankless water heater may be a good option for facilities who want a more energy efficient way to heat their water, and take up less space.

What Is a Tankless Water Heater?

When you hear the term “water heater,” what probably comes to mind is a white, cylindrical tank about four or five feet high and two to three feet wide. Throughout the day you might hear it kicking on, rumbling for a few minutes while it keeps the gallons of water stored in the tank hot. It most likely runs on electric or gas power, although some run on oil or propane as well. It probably sits in a basement or boiler room and heats the water for the entire facility.

That is a typical storage tank water heater. It heats a specific amount of water, maybe 100 or 200 gallons in a commercial facility depending on the size of the tank. That means that when the water in the tank runs out, so does your hot water. You then experience a time delay while waiting for a fresh tank of water to heat up. These types of heaters also use standby energy—that is, they use energy while waiting to be used in addition to the energy they need when running.

A tankless water heater is different. It is a small box that can be placed on the wall, thereby having a much smaller footprint on valuable space. It heats water by passing it through a system of coils, providing on-the-spot hot water as you need it. This eliminates the need for a bulky storage tank, and because it heats water on an as-needed basis, your system becomes more energy efficient.

Installing a Tankless Water Heater

Before installing a tankless water heater, you will need to determine the fuel type, either gas or electric, and flow rates at your facility. You will also need to determine the required temperature rise; this is how much hotter you need your water than the temperature at which it’s coming into the facility.

For example, if your unheated water sits at a temperature of 50 degrees and you need it heated to 110 degrees, your temperature rise is 60 degrees. After determining fuel type flow rate and temperature rise you can choose the right tankless water heater for your facility.

The spot you choose for your tankless water heater installation should be in a place where it can easily connect to a water line and energy source. If you have a gas water heater, you will also have to make sure the area is properly ventilated. You may also need to check the local building codes in your area to see if there are any building code requirements that must be met.

The manufacturer will include instructions on how to properly mount the unit to the wall. When mounting, be sure that the weight is properly supported. Also, be sure to use the proper fasteners and anchors for the type of wall you are drilling into.

After mounting the unit, you can hook up the water line and energy source. If it is an electric unit, you will plug it into the wall. If you have a gas unit, you will need to hook up a gas supply line and light the pilot. Always make sure that the valve to the gas line is shut when running the line; do not reopen the gas valve until the unit is completely installed.

Check the manufacturer’s guidelines for any additional steps or specifications. Be sure to dispose of your old tank water heater properly. You may also consider recycling it, or turning it in for scrap.

Point-of-Use Options

Depending on your need, you may also want to consider point-of-use water heaters to supplement your heating needs. A point of use water heater is a smaller unit that can be installed at the location where the water is being used—for example, under a sink or eyewash station. Point-of-use heaters are also good for areas where you need a higher than usual flow rates, for example where you might be using a high-pressure hose.

Thinking of Buying a Tankless Water Heater?

If you need to upgrade or replace your old water heater, going tankless might be a good option for you. They can offer savings in energy consumption, which saves money. They are small, and since they mount to the wall, they also save you space. They can be placed in the areas where you need it most, offering you a stream of hot water as you need it.


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The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.