Where should tankless water heater not be installed?

Author: Abelardo Bahringer  |  Last update: Tuesday, January 27, 2026

Do NOT install under water pipes or air conditioning lines that might leak or condense moisture that could then drip onto the heater. Do NOT install above electrical boxes or junctions.

Where not to install a tankless water heater?

You should not install your tankless system in an area that is prone to moisture or excess humidity, or where liquids may splash on it.

Where is the best place to put a tankless water heater?

Since a tankless unit is small, you can place it inside the pantry or under the kitchen sink. Keeping the water heater close to your kitchen faucets will help ensure you access hot water quickly and minimize the amount of heat lost when the water flows through the lines.

Can you install a tankless water heater anywhere?

Tankless water heaters can be installed anywhere inside your home. You can even have a tankless water heater in a bathroom! Some families with larger homes choose to install two, one for each floor, for example. Because of their small size, they fit in closets, cabinets, pantries or laundry rooms.

Does a tankless water heater have to be installed on an outside wall?

Typically, the basic requirements are that the tankless water heater system sits on an external wall so that there is room for the ventilation flue. These systems must also be level to ensure proper water and gas flow (if using gas).

3 Things They Don’t Tell You About Tankless

Can I mount a tankless water heater on drywall?

It is not recommended to mount the water heater directly to drywall without some type of rigid support, such as plywood or stud framing. Appropriate fasteners should be used.

How high does a tankless water heater need to be off the ground?

Access and working space must be provided. The opening must be at least 24” wide and large enough to remove the tankless water heater. Tank-less water heaters installed in a garage must be elevated 18” above the floor unless it is listed as having a sealed combustion chamber.

How much clearance is needed around a tankless water heater?

Combustible materials should be kept at least 24 inches away from your water heater and the output hot water pipe. Under normal operation, the cover of your water heater will only warm slightly to the touch, however, it is always best to be overly cautious when dealing with a high voltage appliance.

Why are tankless water heaters installed outside?

* It will increase the resale value of your home. * It's less expensive to install on the outside of the home than the inside. * It doesn't require venting. * An outside tankless model drains directly outside, so there is a significantly reduced risk of flooding than with an indoor traditional tank style.

Can I install a tankless water heater in a closet?

In the closet

You can actually install a tankless unit that supplies your entire home in a closet centrally located in the house.

Why don't more people use tankless water heaters?

Some people hesitate to decide on a tankless water heater because they can be a slightly higher cost; however, you get significantly more life out of one. A standard water heater tank lasts about 8-12 years. A tankless water heater can last as long as 25 years!

How long does it take a plumber to install a tankless water heater?

Installing a tankless water heater typically takes four to five hours, depending on the type of system and a household's needs. The installation process duration also depends on your location and which professionals are available when you need an installation.

Do plumbers recommend tankless water heaters?

Tankless Water Heaters: Tankless water heaters, also known as on-demand or instantaneous water heaters, heat water directly without the need for a storage tank. Plumbers recommend tankless water heaters for their energy efficiency, space-saving design, and endless hot water supply.

Where is the best location for a tankless water heater?

Tips for Indoor Installation
  • Ideal Locations Within the House: Look for a place that's near your main points of water use, such as the kitchen or bathrooms. ...
  • Minimize Noise and Maximize Efficiency: While tankless water heaters aren't overly loud, they do make some noise.

Why avoid a tankless water heater?

Additional Installation Costs

Tankless water heaters are much more complex than traditional hot water tanks. As a result, they require professional installation. If you're switching from a hot water tank to a tankless unit, you will likely need your gas lines rerouted, as well as a larger gas supply line.

Can I replace my 40 gallon water heater with a tankless water heater?

Absolutely! In fact, tankless water heaters are becoming the standard for new home construction because of the energy efficiency.

Should a tankless water heater be inside or outside?

Climate Considerations

In colder areas, outdoor units might need extra insulation or freeze protection to prevent damage during winter. On the other hand, indoor tankless heaters provide better weatherproofing. They are less likely to freeze, offering a more reliable solution in cold climates.

Why does hot water run out quick when you have a tankless water heater?

Although your tankless unit is designed to provide hot water on demand, it has a specific capacity. You can potentially exceed this capacity by running too many faucets or showers at one time. As a result, you can end up with a cold shower.

How do I protect my outdoor tankless water heater?

Choosing a sheltered exterior location can also help prevent freezing issues. If possible, install your outdoor tankless water heater where it will be sheltered from wind, or build an enclosure that blocks the wind. Install a pipe cover to conceal and protect the gas, water and power connections.

What is the code for venting a tankless water heater?

The water heater must be vented in accordance with the section “Venting of Equipment" of the latest edition of the National Fuel Gas Code: ANSI Z223. 1/NFPA 54 in the United States and/or Section 7 of the CAN/CSA B149.

How high off the ground should a tankless water heater be?

While the 18-inch rule is part of the Uniform Plumbing Code, regulations can change from city to city.

How far can a tankless water heater be from a window?

You'll typically need to find a place that's at least three feet from windows, and as close as possible to the vent termination. If your home is several stories tall, you usually can't place the water heater several stories below a roof vent.

Can a water heater sit directly on the ground?

Compliance with Building Codes

In many jurisdictions, building codes require water heaters to be elevated at least 18 inches above floor level. These codes are designed to ensure the safety and proper installation of appliances in residential and commercial buildings.

Does altitude affect a tankless water heater?

GAS tankless water heaters do not work on high elevations/altitudes. As an industry rule of thumb, no tankless works properly above 4,000 ft. Marey units are not recommended above 2,000 ft. People use them on high elevation/altitude locations at their own risk, we do not recommend it.

Why does a hot water heater have to be 18 inches off the ground?

Gas water heaters on 18" stands are typically used to avoid igniting a gas leak along the floor and to make future repairs easier.

Previous article
What is the unsafe temperature for a refrigerator?
Next article
Do HVAC companies clean dryer vents?