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Can a Tankless Water Heater Be Installed Outside?

Can a Tankless Water Heater Be Installed Outside?

I’ve been looking at the possibility of installing a tankless water heater for my pool. They take up significantly less space than traditional water heaters and can be incredibly energy-efficient. But I had to do some research to determine whether or not I could install one outdoors.

A tankless water heater can be installed outside if it’s designed to withstand harsh weather patterns. There are specific models designed for indoor and outdoor usage, so you have to choose the correct type.

Even with an outdoor model, I would still install the water heater under an eave or out of the direct weather if possible.

It’s also a good idea to have it inspected annually once it’s installed.

Throughout this article, you’ll also learn the following information about outdoor tankless water heaters:

  • How to install them yourself vs. hiring an expert
  • Various maintenance and cleaning suggestions
  • Answers to all of your questions about tankless water heaters

How to Install a Tankless Water Heater Outside

Tankless water heaters have countless benefits. If you’re trying to save money and space, there’s no better way to heat your house’s water supply. Fortunately, you can get the whole installation done in under two hours.

Note: If you’re not comfortable working with gas pipes, electricity, and other potentially harmful components, always ask an expert for help. It’s better to pay for the labor costs than to damage yourself or your home.

Looking for a helpful video? Check this one and try it out: 

How to Install a Tankless Water Heater | Ask This Old House

Here’s how you can install a tankless water heater outside of your home:

  1. Remove the old water heater. If gas or electricity is going to the unit, turn it all off and close the valves prior to working on it. Many gas lines have shutoff valves placed throughout the line. Head over to your circuit breaker box and turn off the one labeled for your water heater.
  2. Test the electrical wires with a multimeter. The EtekCity Digital Multimeter is an excellent choice for those who want simple instructions. Touch the corresponding wires to the probes, then read for an electrical charge. If it says that nothing was detected, then you’re ready to move onto the next step.
  3. Unscrew the bolts found throughout the unit. You’ll need to detach it from the wall once you’ve disconnected the electrical wires and potential gas lines. Set it far out of the way, then check for bent, old, or leaking components. Your wires should have at least ½ of an inch of exposed metal, but nothing more than 1 inch.
  4. Mount the new tankless water heater to the wall. Try to cover as many holes from the bolts of the previous heater if possible. The unit should come with brackets or screw holes to mount it easily. Use a leveling tool to ensure that it’s 100% even and level with the wall before you start wiring it up.
  5. Connect the wires and gas line (if you have a gas water heater) to the new unit. Remember not to turn on any of the breakers or the gas valve until you’re done connecting everything. Check for secure connections, and always inspect the gas line for leaks.
  6. Turn on the power to the unit, open the gas valve if you have one, and test your work. Most new tankless water heaters will have a meter that allows you to adjust the water’s temperature. As Mr. Rooter suggests, you should set the temperature of your water heater to 140 degrees Fahrenheit or 60 degrees Celsius.

Maintenance Suggestions

Maintaining your tankless water heater is very important, especially when you’re installing it outside. Although they’re often designed to take a beating from the elements, nothing lasts forever.

You can follow the helpful tips from this section to ensure that you’re getting the most out of your water heater.

Annual Inspections

One of the best suggestions from the Water Filter Spot is to have an annual inspection from a professional. We’ve all made mistakes with DIY jobs and routine checkups, but it’s nice to know that a pro will be able to identify any possible issues.

Some of the common issues that can be found during routine inspections could save you quite a bit of money. Gas leaks and loose wire connections could prove to be incredibly dangerous for your house, but you can avoid those two examples and more with a low-cost checkup every year.

For example, when I purchased an old house years ago, a home inspector realized that the gas furnace’s exhaust flut had been roofed over sometime in the past.

Carbon monoxide was literally boiling out into the attic. Had I not hired a professional, that might have been missed. So sometimes, certain projects are better left to the professionals.

Removing & Preventing Rust

Another example of maintenance would be to remove rust and corrosion. Rust ends up shredding metal over time. Your tankless water heater should be treated for moisture, but there will still be a few parts that take for rain and moisture. Use a balled-up piece of tin foil with diluted dish soap to scrub away any rust that you see.

If you’re concerned about protecting your investment, consider installing the water heater in a shaded area. Since many homes already have a designated spot for their tankless water heater, you could put an awning, tarp, or umbrella over it to protect it from rain, snow, hail, and heavy winds.

Clean the Filter

Finally, clean the filter regularly. There’s nothing worse for your water supply than to have a dirty filter. They’re built to last, but a gross filter clogged with debris can make you sick. The aforementioned professional inspection will deal with this issue. As long as the water temperature is set to a minimum of 140°F (60°C), you’ll be good to go.

FAQ About Outdoor Tankless Water Heaters

As mentioned in the introduction, there are quite a few benefits of installing an outdoor tankless water heater. For example, EccoTemp states that they don’t need to have oxygen-relieving pipes as much as indoor heaters do. They simply expel the gas without clogging your pipes or flooding the house.

That being said, you might still have questions about how they’re used, why they’re preferred, and so on. Let’s answer everything we can below.

  • Are tankless water heaters worth the investment? If you’re trying to save money while using less energy for the environment, then yes, tankless water heaters are more than worth the money. Make sure you choose the correct model to fit outside or inside, depending on the location of your current setup.
  • How much do outdoor tankless water heaters cost? Abacus Plumbing estimates that these water heaters cost anywhere from $1,000 for an electric model to $3,000 or more for a gas-powered model. You should also factor in the potential cost for repiping and rewiring during the quote.
  • Should you choose a gas or electric tankless water heater? According to E-Tankless, gas water heaters are more expensive than electric tankless water heaters, but they’re also less energy-efficient. The only benefit they have over their counterparts is that gas heaters heat the water quicker during the cold months.

Rinnai manufactures natural gas and propane tankless water heaters that are designed for outdoor installation (link to Amazon).

The one thing I would say is that you shouldn’t install a tankless water heater outdoors if it is designed for indoor use. You really want to match the tool to the job.


Tankless water heaters can be installed outdoors if they’re the correct model. Never try to install one that’s meant for inside.

Not only will it get rusted and ruined from the elements, but it’ll also have too many extra parts for releasing pressure and excess condensation and oxygen.

Important Recaps on Tankless Water Heaters:

  • Tankless water heaters are more energy-efficient than tanked water heaters.
  • Electric is almost always more efficient than gas heaters.
  • Schedule an annual inspection to keep up with the recommended maintenance procedures.
  • Get the filter cleaned at least once per year.
  • Set the temperature of your tankless water heater to 140°F (60°C).

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