Hot water heater insulation: Low cost energy saving

All pictures in this post by Renewables At Home – copyright info

Is the top of your hot water heater cool to the touch? If it isn’t, it’s losing heat and wasting money on your behalf. The good news is you can stop this irresponsible behavior – almost for free!

A water heater spends quite a lot of energy to heat water. To prevent this heat from easily escaping, insulation is put in when the heater is assembled.

Unfortunately, manufacturers of hot water heaters never put enough of it in. This means that a significant portion of the energy that is spent heating the water is wasted.

For a while now, I’ve been meaning to do something about my hot water heater, which certainly isn’t cool to the touch. I haven’t really gotten around to it, though, until I was kickstarted by a recent post about heater insulation over at Yanic’s “Adventures into green” blog.

PLEASE NOTE: This post is about insulating electric water heaters. Gas heaters should be insulated by professionals.

Two insulation options

Now, to insulate your water heater, you basically have two options. One of them is reusing old stuff you have lying around the house – more on this further down – or you can buy a commercial water heater blanket or jacket and install it on your heater.

It’s not too expensive ($13 to $32 at Amazon), and is probably the best option if you need it to look reasonably neat and tidy.

Check out Yanic’s post for more info, she has a link to good installation instructions for these blankets, and numbers on how much you might cut your energy costs by (hint: it’s significant, especially considering the low cost of the extra insulation).

Important guidelines

Whether you decide to buy an insulation blanket or reuse old stuff, there are two important guidelines you should follow. Don’t insulate a heater that leaks water (replace it instead). And don’t cocoon your heater completely in insulation. A few parts need to be accessible and not covered by insulation:

• The heater access panel or panels
• The temperature/pressure relief valve and the overflow pipe
• Any electrical wiring leading to your tank

Reusing secondhand insulation

Since my water heater is hidden away inside my kitchen cabinet, I’m not very bothered by how it looks. So I decided to reuse some secondhand insulation I have lying around.

I used a couple of old pillows, a worn-out duvet, an overlay mattress that has seen better days and an old bedspread, but any pliable material that’s designed to keep something warm or cold will do. Blankets and bubble wrap sandwiched in a few layers of each would work well, for example.

These insulation materials can be wrapped around your tank and secured tightly with a few lengths of sturdy tape. Cover as much of the heater as practically possible – especially the top, as this is where most of the heat loss occurs – but do leave the parts listed above uncovered.

If your heater is inside a cabinet or cupboard, trying to reach around it will be hard or impossible, so I recommend just stuffing your insulation materials around it. This is what I did; fully documented with pictures below. Make sure you read on after the pictorial for the final step and some important health and safety advice.

I started out by stuffing the old overlay mattress down into the cabinet’s far left corner.

The next step was pushing a couple of pillows in between the heater’s top surface and the roof of the cabinet. I tried to fill as much of the empty space as possible, but made sure I didn’t stuff the pillows in too hard. Leaving tiny pockets of air between the pillow feathers makes for better insulation than if the feathers are squeezed completely together. Also seen in the picture below is the duvet (on the left).

Here, the duvet is in place and the cabinet front cover is about to be reinstalled.

Inside the cabinet, the end of the duvet is held in place by a bit of sturdy tape, and the bedspread is stuffed in at the back. As you can see, I’ve left the access panel, valves and pipes uncovered. Not exactly a pretty sight, but since the whole spectacle is normally hidden behind other stuff in the cabinet, I don’t really care.

The electrical wiring is also left uncovered, to make absolutely sure it can’t overheat. The wires for heaters should be fairly heat resistant, but I’m not taking any chances.

After you’re done insulating the heater, you might want to look into lowering the water temperature of your heater for further savings. All hot water heaters have a thermostat for adjusting this.

On most heaters, this is usually a small box on the side of the heater or on the wall. If you can’t find it, or if you have to unscrew a panel to find it, you probably need an electrician to adjust it.

Lower the temperature as low as it can go and still leave you with enough hot water for showers and other daily use, but – and this is very important – don’t go any lower than 65 degrees Celcius (149 degrees Fahrenheit).

While you’ll certainly save more energy by lowering it further, you’ll also run the risk of providing Legionella bacteria with excellent growing conditions. This is a serious health risk, and really shouldn’t be taken lightly.

Once you’re done insulating your heater, you can save even more on your water heating bill by insulating the water pipes leading into your heater, too.

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This post was tagged with: energy efficiency, energy saving, heating, hot water, how-to, insulation, legionella, water, water heater

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