Frost King SP57/11C All Season Water Heater Insulation Blanket, 3” Thick x 48” x 75”, R10

Why it's worth it

The Frost King SP57/11C is 3 inches of vinyl-backed fiberglass rated R10, sized to wrap a 40- to 60-gallon tank. It's the strongest option here for a cold basement or an unheated garage, and it costs less than the softer, easier-to-handle alternatives.

If your tank lives somewhere cold, thickness is what matters. Heat leaves a warm steel tank by conduction into the surrounding air, and the only real defense is a lot of insulating material. Three inches of fiberglass at R10 gives you more of that than anything else here. The foil-bubble rolls reflect radiant heat well, but radiant heat isn't your main problem in a 40-degree basement. This is.

The dimensions cover the tanks most people actually own. At 48 by 75 inches, it wraps a standard 40- to 60-gallon cylinder with a little to trim, and the listing covers gas, oil and electric tanks. One owner reports it going around a 67-gallon Rheem with a 63-inch circumference, so there's some margin past the stated range. Measure your tank's height and circumference before you order anyway.

From our review of 6 water heater insulation blankets, by David Sinclair, Managing Editor

What we like

• +If your tank lives somewhere cold, thickness is what matters
• +The dimensions cover the tanks most people actually own
• +Frost King has been making these for decades, and the design has settled into something predictable
• +The vinyl backing does more than look tidy

What to know

• –It's fiberglass, and it behaves like fiberglass
• –Quality control isn't perfectly consistent
• –It stops at 60 gallons