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A water heater blanket can be a simple, affordable way to improve your home’s energy efficiency and help lower your monthly bills. Traditional tank-style water heaters use energy to keep stored water hot, even when no one is using it. If a tankless system isn’t in your budget and your current heater isn’t ready for replacement, adding different types available. This mostly comes down to the type of insulating material. Some are easier to work with during installation than others, as they often need to be trimmed to fit individual water heaters.
- Fiberglass insulation traps heat with a barrier made from pockets of air. Empty space, such as an air pocket, does not conduct heat, so fiberglass insulation is highly effective at insulating a water heater. However, fiberglass insulation is messy, itchy, and no fun to work with, so it’s essential to wear long sleeves, long pants, a mask, gloves, and glasses when installing this insulation.
- Foil insulationworks by reflecting escaping heat back into the water heater. It also creates a thermal barrier with small air bubbles sandwiched between the foil layers. This type of insulation is thinner and much easier to install, but it doesn’t do quite as good a job of insulating as fiberglass.
- Cotton and denim insulation, typically made from recycled clothing such as jeans, is fairly uncommon. Though it works similarly to fiberglass insulation and is reasonably effective, it doesn’t do the job quite as well as fiberglass or foil, yet is more expensive due to the production process. Plus, cotton and denim are not fire-resistant.
- Foil-faced foam insulationworks similarly in theory to foil and fiberglass, using the reflective surface to reflect heat back to the tank. The foam also creates small air pockets. These insulators are usually easy to install and fire-resistant.
You may also find combinations of materials, such as fiberglass insulation with a foil face. This can offer the best of both worlds, as it uses a thick, insulating layer of air pockets and radiates heat back into the tank.
Water heaters, like most appliances, come in different sizes. The size of house and family and the number of sinks and showers all affect how large a water heater a home needs. While water heaters range between 30 and 98 gallons, 40-, 50-, and 60-gallon tanks are the common sizes used in homes.
Water heater blankets also come in similar sizes, so it’s important to find one that will work for your tank. If you have a 50-gallon tank, finding a water heater blanket to fit it should be no problem. Water heater blankets large enough to fit 98-gallon tanks, commonly found in commercial settings, may be harder to track down.
Thickness
When it comes to materials such as fiberglass, cotton, and denim, the thicker the water heater blanket, the better it will be at insulating. A water heater located in a cool basement calls for a thicker blanket. Thicker blankets will do a better job of separating the cool air and the heat radiating from the tank than thinner ones.
Because foil works primarily by reflecting the heat instead of relying on an air-pocket barrier, it needn’t be thick to function efficiently. Most water heater blankets made with foil are less than ½ inch thick, which is another reason foil water heater blankets are so easy to work with.
Insulating Power
Just like your home’s insulation, water heater blankets come in a variety of insulation ratings. These ratings are described as R-value, where the R stands for resistance. The higher the R-value, the more resistance the insulation has against heat transfer. Essentially, more is better.
The highest R-value you’re likely to find for a residential water heater blanket is R-11, but values of R-7 and R-8 are more common. To get the most from your investment, it’s best to use the water heater blanket with the highest R-value.
It’s important to keep in mind, though, that foil-type insulation rarely offers an R-value; R-values apply to fiberglass and other similar types of insulation.
Fire Resistance
Water heaters have burner assemblies that get very hot. The point of insulating a water heater is to save energy and money, not cause a fire. Different water heater blanket materials have varying degrees of fire resistance to combat that risk. While the most common designation is Class 1/Class A, it’s helpful to know which types are the most fire resistant.
- Fiberglass and foil-type insulation are nonflammable.
- Cotton and denim are flammable and not likely to have a fire-resistance rating.
If fire resistance is of utmost importance, a fiberglass or foil water heater blanket is the way to go. Some fiberglass or foil products aren’t fire rated, but that doesn’t mean they’re unsafe. Just be sure to keep the insulation clear of the burner by a few inches.
Versatility
There are two types of water heaters: electric and gas. Electric water heaters have a heating element inside that energizes and heats the water that surrounds it. Gas water heaters have burners underneath that kick on to heat water through convection.
Fortunately, water heater blankets are interchangeable between the two water heater types. However, if you have a gas-powered heater, it’s crucial that the blanket doesn’t cover or otherwise obstruct the flue (aka exhaust) at the top. If you have an electric model, the blanket must not cover or obstruct its control box or access panel, typically located on the side of the tank. Also, be sure to cut the insulation back from the burner by at least 2 inches while installing.
For additional information about buying and using the best water heater blanket, consider the answers to these frequently asked questions.
Q. What makes a great water heater blanket?
A great water heater blanket will offer a blend of insulation value, cost-effectiveness, and fire resistance.
Q. What size water heater blanket do I need?
It depends on the size of your tank. Generally speaking, manufacturers label their water heater blankets according to the size of the tank they’ll cover. If you’re unsure, measure your tank’s height and circumference, and compare it to the measurements on the package.
Q. Do I need to maintain my water heater blanket?
Water heater blankets are low maintenance, but fiberglass, cotton, and denim can begin to smell and stop insulating if they get wet. It’s a good idea to check on your water heater blanket a few times a year to ensure it’s still in good condition.
Q. How long will my water heater blanket last?
Undamaged water heater blankets may far outlast a water heater. The average gas water heater lasts between 8 and 12 years, while the average electric water heater lasts 10 to 15 years. A water heater blanket kept in good condition will outlast a water heater without issue.
Q.How do you install a water heater blanket?
The most efficient way to install a water heater blanket is to measure the height and circumference of your tank before unrolling the product, allowing for an extra 2 inches for the circumference so you can overlap the product. Premeasuring allows you to swiftly cut the product to size using cutter or scissors. Wrap the tank with the blanket, and secure it in place with foil tape placed vertically along the seam. Cover the top of the tank with two half circles of material, and secure it in place with foil tape. Ensure that you cut openings for the venting hood, pressure relief valve, burner access cover, and wiring connection box. Make the holes about 2 inches larger than each opening to allow airflow.
Q.Is a water heater blanket worth it?
Yes. Any steps you can take to keep your water hot without additional reheating of the water is worth it. The water heater blanket does just this and is an inexpensive purchase. In most cases, you should be able to recoup your investment when installing an insulator blanket.
Q. Are water heater blankets safe?
Yes. When properly installed, hot water heater blankets are safe to use. The most important thing is to ensure proper airflow around all fixtures by cutting slightly larger openings around valves, hoods, burners, etc. Don’t forget that some blankets contain fiberglass, and those installing the product should wear safety goggles, a dust mask, gloves, and long sleeves, then carefully clean the area after installation to remove any stray fiberglass fibers.
Meet the Tester
Jodi Webb is a DIYer who tests products with her contractor husband so readers get the advantages of both an expert’s and DIYer’s viewpoint. She visited several neighbors bearing water heater blankets and was able to test the product in a variety of setups.
Additional research provided by Tom Scalisi.
