Winter can be brutal. It exposes weaknesses in our homes, whether that’s leaky windows, ice dams on the roof, or poor insulation letting heat escape through the walls. Something else may be losing heat for lack of proper insulation, too–your water heater. Fortunately, insulating a water heater is a simple fix that most people can perform in about an hour.

Why Wrap your Water Heater?

There are two things to understand about heat to answer this question. The first is that when two things are in contact and are different temperatures, heat always moves from the warmer thing to the cooler thing. Secondly, the further apart the temperatures, the faster heat is transferred.

The tank surface of a water heater is warmer than the surrounding air, meaning that heat will transfer to the air instead of heating your water. This is called standby heat loss, and it can add up to 20% to your heating costs. Now think about the air in winter. It’s much cooler, meaning the difference between it and your tank temperature will be greater, and the rate of standby heat loss increases. Wrapping your heater in an insulating blanket can cut heat loss nearly in half.

Choosing a Blanket

There are a few things to check before buying a wrap kit. It’s helpful to know your water heater’s R-value, which indicates how much insulation the heater already has. This number is usually found on the side of the tank. Older heaters have lower R-values, meaning they need more insulation. Heater wraps also have R-values, with higher numbers offering more insulation. If your heater has an R-value of 16 or less, choose a wrap with an R-value of 10 or higher. If the heater is rated above 16, go for a lighter wrap with an R-value under 10. If you don’t know the heater’s R-value, and the heater’s surface feels warm or it’s an older model, use the heavier wrap.

Installing a Wrap Blanket

First, look for corrosion or leaks on your heater. You don’t want to cover up any problems. You may also want to use gloves and dust masks if your blanket has fiberglass insulation. Now turn off the breaker if it’s an electric heater, or put a gas heater on the pilot setting. Measure the water heater’s height and trim the blanket if necessary.
Temporarily wrap the blanket around the heater and mark the spots to cut out. You’ll need openings for the:

• Thermostat & any other controls
• Drain valve
• Pressure relief valve & drain pipe
• Gas valves (for gas heaters)
• Burner (for gas heaters)

For gas units, be sure not to block the flue or draft diverter on top of the heater or air flow to the burner at the bottom.
Now you can re-wrap the heater and tape it in place. That wasn’t so bad, was it? This inexpensive project can save you hundreds of dollars over the life of your water heater. Winter will still be winter, but this is one way you can reduce its chilling effect on your heating bill.

Charlie Teschner started MESA Plumbing, Heating, and Cooling in 1982. Charlie has a journeyman and master plumber’s license. He was raised with a strong work ethic and he now applies those values to tasks such as Longmont, CO heating repair.