The Department of Energy says an insulation blanket is worth considering on an electric water heater and accomplishes nothing on a gas one. Its savings-project page for insulating a water heater tank says most experts agree heat loss in a gas water heater goes up the flue, so a blanket serves no purpose for those units. For electric units it says insulation could reduce standby heat losses and save on water heating costs, with caveats we set out below. That page no longer loads at its original address, so we cite an archived copy captured on January 18, 2025.
What Federal Guidance Says For Electric Water Heaters
DOE says insulation could reduce standby heat losses by 25 to 45 percent and save about 7 to 16 percent in water heating costs. Those are DOE’s figures for an electric water heater, and the word “could” is DOE’s. It adds that such a project should pay for itself in about a year and that pre-cut jackets or blankets are available from around $20. It suggests first checking an older heater for existing insulation with an R-value of at least 24, and says that if you do not know the R-value you can touch the tank; it suggests considering insulating an electric heater if the tank is warm to the touch.
For an electric unit being newly installed, DOE also says insulating underneath the tank with a rigid bottom board could save another 4 to 9 percent of water heating energy. Separately, DOE’s archived storage water heater guidance says to look for models with tanks that have a thermal resistance of R-24 and above to avoid adding an insulation blanket, for electric water heaters only.
What Federal Guidance Says For Gas Water Heaters
DOE says most experts agree heat loss in a gas water heater goes up the flue, so a blanket accomplishes no purpose. That is the page’s whole treatment of gas units, and we do not go beyond it. Our carbon monoxide guide explains why the area around a gas unit’s vent and air supply is not something to wrap or block.
Questions about your heater’s standby losses? Call (717) 500-8528.
What Must Stay Uncovered
DOE and the manufacturer agree on what a blanket must not cover. DOE lists hazards homeowners unknowingly create: covering safety warnings and operating instructions; covering controls, access areas, shut-off devices and temperature and pressure relief valves; and blocking air passages required for combustion or draft, resulting in unsafe operation. It adds that the water heater manufacturer disclaims any liability for problems associated with insulation blankets, and that some local codes and utility company regulations may prohibit them.
State Water Heaters’ electric manual says the same in its own words: when installing an external insulation jacket on an electric water heater, do not cover the temperature-pressure relief valve, do not put insulation over the access covers or any access areas, and do not cover or remove the operating instructions and safety-related warning labels. For why that valve must stay clear, see our T&P relief valve guide. DOE also says not to set the thermostat above 130 degrees Fahrenheit on an electric water heater with an insulating jacket or blanket, because the wiring may overheat.
Why This Page Gives No Installation Steps
Wrapping a water heater means working next to a relief valve, controls and access panels. The DOE page does include step-by-step instructions, and it also lists the hazards above. We point to those hazards and to your heater’s own manual instead of reproducing a procedure. A technician can check what your unit can safely wear during water heater maintenance.
What This Page Will Not Tell You
It will not tell you what a blanket would do for your bill at your address. The percentages above are national statements with a qualifier, and the result depends on the tank, where it sits and what you pay for electricity. We publish no payback figure for Lancaster. The page also does not address heat pump or tankless water heaters, and it says nothing about whether a manufacturer permits a blanket on a given model; the manual for that model governs.
Not Sure What Your Water Heater Can Safely Wear?
Service requests and emergency service are available 24/7 across Lancaster City and Lancaster County.
Call For Emergency ServiceInsulation Blanket FAQ
Does an insulation blanket help a water heater?
The DOE says it could on an electric water heater and accomplishes nothing on a gas one. For electric units DOE says insulation could reduce standby heat losses by 25 to 45 percent and save about 7 to 16 percent in water heating costs. For gas units it says most experts agree heat loss goes up the flue, so a blanket serves no purpose. We cite an archived copy of that page.
Should I put an insulation blanket on a gas water heater?
DOE says there is no purpose in it. Its savings-project page says most experts agree heat loss in a gas water heater goes up the flue. DOE also lists blocking air passages required for combustion or draft as a hazard of blankets. Check your heater’s manual and ask a technician before covering anything on a gas unit.
What should an insulation blanket never cover?
Per DOE and State Water Heaters, the relief valve, controls, access areas, warning labels and operating instructions. DOE also lists shut-off devices and air passages required for combustion or draft. State Water Heaters’ electric manual says not to cover the temperature-pressure relief valve, the access covers, or the safety labels.
Do I need a blanket if my water heater is new?
DOE’s archived storage water heater guidance says to look for tanks with a thermal resistance of R-24 and above to avoid adding an insulation blanket, for electric water heaters only. Check the rating on the unit you are buying, and check the existing insulation if you have an older tank.
Can a blanket cause a water heater problem?
DOE says it can when it covers or blocks the wrong parts. It lists covering safety warnings, controls, access areas, shut-off devices and relief valves, and blocking air for combustion or draft. It also says not to set the thermostat above 130 degrees Fahrenheit on an electric water heater with a jacket, because the wiring may overheat.
Who can check my water heater near me in Lancaster County?
Lancaster Water Heater Pros services water heaters across Lancaster City and Lancaster County. Call (717) 500-8528 with your model number and fuel type. Service requests are accepted 24/7.