Water storage tanks insulation

Insulating an electric hot water storage tank is a typically inexpensive and easy DIY task. Insulating a gas or oil water storage tank is also inexpensive but not so easily.

New storage water heaters have good insulation. But if it isn’t the case of your tank, you may save some money (up to 10% of your water heating bills) by insulating it.

How to know if the water Storage tank needs insulation?

To know if a water tank is poorly insulated, just touch it. If it is warm to the touch, then it needs insulation.

New qualified storage water Tanks and alternatives to them

There are now new qualified storage water heaters, more efficient and with better insulation than older models. And also several energy-efficient alternatives, namely condensing and solar units that you should consider as an alternative to your old storage tank insulation...

Cares when insulating the tank

But if you are considering the insulation of your water storage tank, you should begin by reading carefully the water heater manufacturer’s instructions to see if additional insulation is allowed. Some manufacturers may void the warranty if any insulation is added to their storage tanks.

If additional insulation is permitted, follow the manufacturer’s instructions carefully: some parts of the system can’t be covered safely or efficiently, and that should be taken into account, namely in the case of gas and oil hot-water heaters.

The tank air vents, the drain and the flue should be clear at all times: and the insulation should never interfere with that. Also leave the thermostat uncovered, and never insulate the top of a gas water storage tank. Also do not install insulation on a leaking unit.

Gas and oil water storage tanks are much more difficult to insulate than electric ones, and unless you are following the manufacturer’s instructions and you are absolutely sure of what you are doing, it's best to have a professional to add the insulation.

The cost and R-value  

Pre-cut jackets and blankets for water storage tanks insulation are available from around $10–$20. Just choose one with a good insulating value (an R-value of at least R-8).

Electric Water Storage Tanks Insulation

A pre-cut jacket or blanket makes the installation of the insulation a very easy job, but it is very important to read and follow the manufacturer’s instructions carefully.

The instructions should coincide, in their basics, with the steps we list below (steps and images following EERE/EnergySavers instructions):

Water storage tank insulation: step 1Water storage tank insulation: step 2Water storage tank insulation: step 3Water storage tank insulation: step 4

Image 1,2,3,4, from EERE

  1. Cut an insulation section for the tank top, to fit around its piping. Place it, tape it and fold the corners down; also tape the corners to the tank as shown in Image 1.

  2. Position the blanket around the tank; The ends should not come together over the access panel(s); secure the blanket in place with the belts; fit them snugly over the blanket, without compressing it more than 20% of its thickness (Image 2).

  3. If the heater has the overflow pipe or/and the temperature/pressure relief valve on its side, do not cover it/them.  Also leave the access panel and the instruction plate uncovered, cutting the insulating blanket accordingly (Images 3 and 4).

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