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In the decade I spent outside the United States, none of the homes I lived in had hot water instantly available 24 hours a day. The hot water storage tanks were small, and when they were empty, that batch of hot water was gone. To get more, you had to turn on the hot water heater, and wait at least a half hour for enough water to accumulate in the tank to take a decent shower, or do a sink’s worth of dishes.
This took some getting used to initially, but once I got in the habit of only heating the water that I’d use right away, the idea of having a giant tank that not only stores a large amount of hot water, but keeps it heated around the clock sounded a) luxurious, and b) extremely expensive. Now that I’m back in the U.S., I can confirm that I was correct on both counts. Fortunately, there’s a way we can help our hot water heater keep its tank of water at the right temperature without having to use quite so much energy: Wrapping it in a special insulating blanket. Let’s get cozy.
What is a hot water heater blanket?
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A hot water heater blanket—also known as a jacket—is exactly what it sounds like: A sheet of insulation made from fiberglass, foam, foil, or a combination of materials that wraps around a hot water heater’s tank to help it maintain its temperature. With less heat escaping from the tank, the hot water heater won’t have to use as much energy to keep the water inside of it hot.
These insulating blankets are especially useful if your hot water heater is located in your basement—as opposed to in a utility closet on or above the ground floor—because it’s probably colder down there, and therefore would need to use more energy to keep the water hot inside the tank.
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What is an R-value?
When looking at hot water heater blankets, or even your tank itself, you may come across a rating called an R-value, which is determined by how effective an insulating material is at resisting heat flow. The better the insulation, the higher the R-value.
According to the U.S. Department of Energy (DOE), your hot water heater tank itself should have an R-value of at least 24. You can usually find the R-value on a sticker on the tank or in the owner’s manual, but if you can’t, carefully touch the outside of the tank: If it’s hot or warm, it likely needs to be insulated—but the DOE recommends insulating it even if it’s not.
Do hot water heater blankets really work?
By the DOE’s calculations, your hot water heater blanket should pay for itself in roughly a year. This is because the agency estimates that insulating your hot water heater’s tank can reduce its standby heat losses by between 25 and 45%, which should translate to a savings of approximately seven to 16% in water-heating costs.
Although most of these blankets indicate that they’re safe to use on the tanks of both electric and gas-powered hot water heaters, according to the DOE’s website, “most experts agree that heat loss in a gas water heater goes up the flue,” so a blanket “accomplishes no purpose for these types of heaters.” That said, others have pointed out that if your gas hot water heater is old, and the tank isn’t well insulated, a blanket should help at least a little—just be sure not to cover the flue, or have any part of the blanket touching the bottom of the heater (or wherever the flame is located).
Lastly, the DOE also recommends checking your local codes and utility company regulations before purchasing or installing an insulation blanket, as they’re prohibited in some areas.
What to consider when buying a hot water heater blanket
The biggest decision you’ll have to make when purchasing a hot water heater blanket is whether or not to get one made from fiberglass. While fiberglass is the thickest and most effective type of insulation for a hot water tank, it’s also messy, shedding little fibers that go everywhere and are dangerous to breathe in (so you need to wear a face mask when working with it). It’s also uncomfortable and itchy to touch.
If you’d prefer avoiding fiberglass, you can get a hot water heater blanket made from a combination of foil, foam, and (special) bubble wrap. It’s not as effective as fiberglass, but it’s easier (and less uncomfortable) to install.
Most hot water heater blankets cost somewhere between $30 and $50 and are easy to install yourself, especially because they typically come pre-cut to fit your tank, often as part of a kit, along with heat-resistant tape, step-by-step instructions, and sometimes even a small knife for trimming any excess insulation. Here are a few of my favorites:
Reflecto-Foil Water Heater Jacket ($38.88): This kit comes with enough material to cover a 40-gallon tank, but a larger kit is also available. In addition to the reflective foil and tape, a small utility knife is also included.
Frost King SP57/11C All Season Water Heater Insulation Blanket ($30.47): This three-inch-thick vinyl-backed fiberglass blanket provides the superior insulation of fiberglass, but with less shedding than other products made from the material. It’s supposed to fit hot water tanks as large as 60 gallons, but in practice, it can be hard getting it to fit tanks that hold more than 50 gallons (unless you want to really stretch it out).
SmartJACKET Water Heater Insulation Blanket ($47.85): Made from 99% aluminum foil, this insulating blanket is designed to fit most 20- to 80-gallon hot water heater tanks.
Reach Barrier 3016 Water Heater Insulation Kit ($33.73): This kit comes with a pre-cut panel of foil-covered bubble wrap insulation and temperature-resistant tape, making installation quick and easy.
US Energy NASATECH Water Heater Insulation Jacket Kit ($44.44): This non-fiberglass insulation kit comes with 42-square-feet of material, which should fit most 20- to 80-gallon tanks.
Be sure to take measurements of your hot water heater tank before making a purchase: These blankets aren’t one-size-fits-all.