Insulating My Water Heater
11/09/2005 09:05:00 PM | Author: baloghblog
Or, how I turned my hot water tank into a big (energy efficient) marshmallow.

US Department of Energy:
Insulate Your Water Heater Tank for Energy Savings:

Unless your water heater's storage tank already has a high R-value of insulation (at least R-24), adding insulation to it can reduce standby heat losses by 25%–45%. This will save you around 4%–9% in water heating costs.

If you don't know your water heater tank's R-value, touch it. A tank that's warm to the touch needs additional insulation.

Insulating your storage water heater tank is fairly simple and inexpensive, and it will pay for itself in about a year. You can find pre-cut jackets or blankets available from around $10–$20. Choose one with an insulating value of at least R-8. Some utilities sell them at low prices, offer rebates, and even install them at a low or no cost.

First I insulated the copper pipes with Polyethylene.

Insulating your hot water pipes reduces heat loss and can raise water temperature 2ºF–4ºF hotter than uninsulated pipes can deliver, allowing for a lower water temperature setting. You also won't have to wait as long for hot water when you turn on a faucet or showerhead, which helps conserve water.

Insulate all accessible hot water pipes, especially within 3 feet of the water heater. It's also a good idea to insulate the cold water inlet pipes for the first 3 feet.

Use quality pipe insulation wrap, or neatly tape strips of fiberglass insulation around the pipes. Pipe sleeves made with polyethylene or neoprene foam are the most commonly used insulation. Match the pipe sleeve's inside diameter to the pipe's outside diameter for a snug fit. Place the pipe sleeve so the seam will be face down on the pipe. Tape, wire, or clamp (with a cable tie ) it every foot or two to secure it to the pipe. If you use tape, some recommend using acrylic tape instead of duct tape.

slides right over existing pipe, just cut to length:

pressed into place and then taped up with duct tape: (yes that is my thumb)

Ozone friendly? I guess so, that's what the label says...

Next I moved on to the insulating "blanket", which I wrapped around the water heater and cut to length. It cut easily with my trusty swiss army knife.

Nude water heater:

There was just enough tape to make it fit on there:

Finished product, note that the electrical components are kept uncovered:

(The BIG marshmallow!)

Here is a close up of the top, again left uninsulated according to directions because it is a gas water heater. Note the insulated hot water pipe leaving the top is now all taped and insulated as well:

I hope to save money on our natural gas portion of the energy bill, by this insulation and by reducing the setting on the thermostat. I was shocked to see that it was on full blast high setting. That was quickly remedied! We will test out the level that it is now and make adjustments higher or lower depending on comfort.

Shaving at minimum 10-15% off of last winters energy bill is my goal. We are attempting to do this by:
  • reducing thermostat on heat to 68 degrees on our programmable thermostat when we are home and down to 62 degrees during the day when we are not.
  • installing low-e energy star windows, and insulating around them
  • wrapping hot water tank and hot water pipes as above
The windows are an ongoing large project, but this was an inexpensive quick way to increase your homes energy efficiency. I completed the whole thing in about 1 hour, and I highly recommend it if you own.

Given the fact that our EnergyGuide was written in 1994, I suspect that this water heater is at least 10 years old. With a average life-span of 13 years, there are only a few good years left in it. At that time I'll replace with a more energy efficient Energy Star model, or, if we are going to stay in this home for the long haul - an on-demand hot water heater.
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On 1:02 PM , j&c said...

Nice job! We just replaced our water heater. Unfortunately, there are no Energy Star standards for water heaters. This shows the list of appliances that do have standards.

There are more efficient models of water heaters available though. Look for high insulation values and high burner efficiencies. Since you have gas, I would recommend the instantaneous route though. It would eliminate storage losses and would get you hot water quicker. Depending on which model you chose, you might need one for each bathroom.

BTW, do NOT insulate the exhaust stack. It would be very dangerous and could cause gases of combustion to come into the house. It doesn't look like you're going to, but I've seen some pretty silly things ;)

Good luck, and keep us updated!

On 1:09 PM , Anonymous said...

I my exposed hot water pipes over a year ago, and insulated the water heater (gas) earlier this year. I also turned down the temperature setting to 120F when I insulated the pipes.

I noticed a difference after insulating the pipes, hot/warm water arrived sooner.

I haven't noticed any real change after insulating the water heater. But since the insulating jacket was $12 it is an experiment worth doing.

Of course, the fact that the water heater is in the basement and I'm on the second floor also influences things.

The duct taping job is impressive.

On 4:44 AM , UNplanner said...

At an age of 10 years, you shouldn't feel bad about junking your heater now. Those things gunk up on the inside and become less efficient regardless how much else you do to improve their efficiency. Start looking on EBay for on-demand heaters and if you locate a real steal, by all means go for it. Use the term "tankless" when searching.

If you can get a combination solar water heater with a back-up electricity tankless heater you'd be miles ahead of others out there.

On 10:23 PM , Anonymous said...

I read your articles, and I thought insulating my water heater was worth the couple of bucks. I looked online and found a pretty helpful site which sold the heater insulation and pipe insulation (rubber and fiberglass) Thought you should link the site that I got this stuff from. The place is

On 12:11 PM , Susan said...

My Dad has insulated his tank, but has also noticed that the exhaust line that goes out of the house is extremely hot. Is this dangerous? I saw in the blog someone said to never insulate the exhaust, but we were worried about the effects of the exhaust being so hot. What should he do?