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How Hard Is It To Install a Tankless Water Heater?

by | Jan 13, 2017 | Plumbing Guides

In short, the answer depends on what brand and type of tankless water heater you buy. There are many factors that affect the difficulty of installation, like the clarity of the manufacturer’s installation instructions and the type of existing venting your home has.

However, the question is not how hard it is to install a tankless water heater, but if you should.

The answer to that question is no.

Although there is an increasing number of homeowners who have successfully installed a tankless water heater themselves, manufacturers strongly encourage buyers not to. First and foremost, there is the issue of safety. For example, if a gas powered tankless water heater is not properly connected to its gas supply line, a gas leak could develop. Likewise, if the existing wiring in your home cannot adequately supply electricity to your tankless water heater, there is a small chance that the wiring could short, which could potentially start an electric fire. Secondly, most manufacturers will not honor the warranties they provide on tankless water heaters unless the unit is installed by licensed professional. Should a problem arise with the unit you’ve purchased, and you chose to install it yourself, you could be out hundreds, if not thousands, of dollars.

The Realities of Installing a Tankless Water Heater

It is a common myth that tankless water heaters are the “plug and play” variety. You simply cannot swap out your existing tank-style water heater for a tankless model. Modern traditional, gas-powered water heaters are not installed in a home with tankless retrofitting in mind. There is a real possibility that your home’s existing gas line, gas meter, and piping are not appropriately sized to handle the high demand for gas that a tankless water heater would require. Similarly, tank style water heaters have different venting requirements than tankless models do, and there is a good chance that your home’s existing venting will need to be revamped should you choose to install a tankless model.

Many homeowners who experience dissatisfaction with their tankless water heaters usually do so due to one of these reasons. Buyers must also have realistic expectations regarding the performance of the tankless water heater they intend to buy. No two brands of tankless heaters are exactly alike, and an improperly installed unit will more than likely underperform.

Permits & Inspections

Many cities and communities now require permits to be obtained and inspections to be conducted before and after the installation of a tankless water heater. Just a few of the permits one may need to obtain include electrical permits, gas piping permits, and mechanical permits. The requirements will differ depending on what jurisdiction you live in.

A standard, 40-gallon water heater with a storage tank operates off an input of 40,000 BTUs per hour. Most modern tankless water heaters operate in the range of 11,000 to 199,000 BTUs per hour. Carbon monoxide and exhaust emissions produced by each type of water heater are completely different, as are their venting requirements. For these reasons, it is important to follow all requirements set forth by your local authorities. An expert hot water heater plumber will have the knowledge and skills required to obtain and meet all permit requirements during the installation process.


Before you make the switch, make sure to read plenty of reviews of tankless water heaters. Get quotes from several professionals to determine who has the best prices, and don’t forget to check online references and reviews for each one. Get estimates for how much it will cost to update your home’s current venting as well as its current electrical system or gas fittings. Just because you think you can install your new tankless heater by yourself doesn’t mean you should. Risking your health and safety is not worth saving a few bucks.

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