Garage Water Heaters: 7 Things You Need to Know

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In many homes, your hot water heater is either in the basement or garage. Depending on your home’s layout, the garage may be the best option where to put it.

Ambient temperatures, state or local building codes, and the overall look of your garage are just a few factors you should consider when deciding where to put your water heater.

Let’s look at some questions a homeowner should consider before installing a garage water heater.

Can Water Heaters Be Installed in a Garage?

Yes, you can install your water heater in the garage. I have my hot water heater installed in my garage, actually.

The garage is a great spot for a water heater if there’s no good location anywhere else in your home. This is especially true if you don’t have a basement, like homes here in Florida.

Keeping your water heater in the garage keeps it out of sight and out of mind.

However, your garage must be prepared so your water heater can work efficiently.

If you have a gas water heater, you’ll need to run a gas line to your garage. Gas water heaters also need sufficient venting.

The National Electric Code (NEC) offers wiring guidelines for electric water heaters. They recommend wiring a circuit for 125% of the expected load.

For example, a 4500w electric heater would require a 240-volt dedicated 30-amp circuit and 8-gauge copper wire.

No matter whether you have a gas or electric water heater, your garage needs to be able to handle the power.

Where you put your garage water heater is also critical. Gas water heaters will have a pilot light, and electric water heaters will have heating elements. Both are usually near the base of the unit.

Either one can pose a danger when exposed to leaks, vapors, or flammable materials. In many jurisdictions, the building codes require water heaters to be a certain distance above the ground.

Check your local building codes before you install your water heater.

Be sure, also, to look at what’s the best garage floor coating to apply under your water heater to minimize water damage.

Can You Install a Heat Pump Water Heater to Cool the Garage?

I’ve been looking into heat-pump water heaters (HPWH) for my garage.

They can be a cost-effective and energy-efficient alternative to traditional water heaters that also help cool the space.

They’re perfect to install in your garage, especially if you live in the southern part of the country, where there’s a lot of warm air around the unit. 

An HWPH draws heat from the air to warm the water in its tank. It then exhausts the cool air back into the garage.

If you want to install an HPWH in your garage, the EPA’s EnergyStar program has some special considerations.

There’s less benefit to having a heat-pump water heater if your garage is air-conditioned or you live in cooler climates.

When the surrounding air is already cool, a heat pump water heater can’t pull enough warm air into the system. It needs to rely on the electric heating element. At that point, it’s operating exactly like a standard electric water heater.

The air around a heat pump water heater must remain between 40º–90ºF (4.4º–32.2ºC) year-round.

Finally, the average HPWH will require approximately 1,000 cubic feet (28.3 cubic meters) of air space around the unit. That’s the size of a tiny, single-car garage. Anything larger than that will be fine.

What Is the Building Code for a Garage Water Heater?

As with anything, the applicable building codes for water heaters will depend on where you live. There are federal, state, and local regulations that you’ll need to comply with. Check with your local government before installing a water heater in your garage.

Some of the relevant codes that you should review include:

  • The International Residential Code (IRC)
  • The National Electrical Code (NEC)
  • The National Fuel Gas Code (NFPA 54)
  • State and local regulatory codes

Here are some of the most common codes that you should familiarize yourself with before installing a water heater in your garage:

  • Location: Regulations usually require that your heater is installed at least 18” off the floor. This helps avoid contact with leaks or flammable vapors.
  • Bottom Boards: An insulation buffer that is designed to reduce heat loss. It is required for electric heaters installed in unheated areas.
  • Drain Pan: Many municipalities require a pan beneath the water heater to catch leaking water. It must be made of approved material.
  • Relief Valve and Dedicated Shut-off Valve: A relief valve helps to vent pressure inside the tank of the heater. A shut-off valve turns off the water supply to the heater, without removing water service to the rest of the house.

Again, these are just some of the more common requirements for a water heater in a garage. Check with your local code enforcement office before installing your water heater.

Will My Water Heater Freeze in the Garage?

Any water left long enough in freezing temperatures can freeze. However, as long as your water heater has power, the risk of the water inside freezing is low. This is true even if your water heater is in the garage.

Storage tank water heaters are insulated to help ensure that the water inside stays hot for a long time.

That helps make them more energy efficient because they’re not constantly drawing power for heating. A side-effect is that the water inside is protected when the surrounding air temperature drops.

Remember that older water heaters were designed with thinner insulation than newer models.

However, even older units could benefit from an insulating blanket to help improve their R-value. This represents how resistant to heat loss your heater is.

The higher the value, the better the insulation.

If you live in an area that loses power during the winter, it’s possible to winterize your water heater.

This helps ensure the water in the tank won’t freeze. It also helps save money on your energy bill by reducing heat loss during the winter.

Read the section below to learn an easy method for insulating your water heater and reducing heat loss.

Alternatively, you can install a tankless water heater in an unheated garage. The internal heat generated will keep the pipes warm even if the air around it is freezing.

How Can I Hide My Water Heater in My Garage?

Installing your water heater in your garage can be a great way to clear out space in your house. However, you may not want to see the heater every time you’re in your garage.

There are some options to make your water heater less conspicuous in your garage.

Here are a few popular options for hiding your garage water heater:

  • Curtains: One of the cheapest and easiest options on the list. If your heater is positioned in a recessed spot in your garage then a curtain is a great option. Installing a curtain rod will only take a few minutes and gives you lots of design options. Bonus: It is easy to slide the curtain to the side when you need to access your heater.
  • Dividing Screen: A fold-out dividing screen will only cost a little more than a curtain and removes the need to install a curtain rod. Dividing screens work regardless of where in your garage your heater is and they are easy to move.
  • Cabinet: If you are a little handier, then building a cabinet or full enclosure around your heater can be a great option. A cabinet provides a more permanent option and gives a finished appearance to your garage.

Should I Wrap My Garage Water Heater With Insulation?

Most modern gas and electric water heaters have built-in insulation. That should be safe enough in your garage despite freezing temperatures.

However, if the temperature in your garage drops below freezing, it could still pose a problem for your hot water heater. Insulating the heater can be wise if you’re concerned about losing power during the winter.

An insulation blanket specifically designed for water heaters is one of the most efficient, cost-effective ways to add insulation to your water heater.

Water heater blankets are rated with an R-value, just like other insulation. The higher the R-value, the less heat escapes your garage water heater.

The U.S. Department of Energy recommends using an insulation blanket of at least an R-value of 7 or higher. One of the highest-rated blankets available to consumers is an R-11 blanket but at a substantially higher cost.

Be sure to purchase a blanket that matches the size of your garage water heater!

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Can You Use a Bug Bomb in Garage With Water Heater?

Because a bug bomb relies on pressurized aerosol propellants, it is considered flammable. That makes it dangerous if used around ignition sources such as those found on a water heater.

The pilot light on a gas water heater or an electric water heater’s electrical components could cause the aerosol to ignite.

The Environmental Protection Agency recommends taking precautions before using a bug bomb:

  1. Extinguish all ignition sources, such as the pilot light on a gas water heater. 
  2. Turn off power to all electrical devices to ensure no spark from an appliance such as a water heater cycling on and off.
  3. Place the bug bomb at least six feet from any ignition sources in the area.
  4. Only use one bug bomb, typically 6oz in volume, per 25 by 25-foot area.
  5. After use, air out the treated area to remove all flammable vapor. Place fans in doors and windows to help speed up the process.

Always remember to read and carefully follow the instructions with the bug bomb before using it.

If you need assistance shutting off your ignition sources or have any other questions, contact your local gas utility company.

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Tim Wells

Tim Wells, the founder of Garage Transformed, has been featured in dozens of home renovation publications, including, Home Stratosphere, House Digest, Livingetc, and SFGate. Since 2018, he has helped over two million people transform their everyday garages into something they can be proud of. He lives in Central Florida with his wife and bulldog.

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