How to Insulate Outdoor Tankless Water Heater

Outdoor tankless water heaters help homeowners to save water. They provide a continuous supply of hot water and instantly heat the water as you need it.

But do you know that these outdoor heaters require extra care during cold weather? If water heaters installed indoors can be damaged by cold weather, how about an outdoor one? A serious case, right?

Therefore, to endure the winter, you need to ensure that the water heater is perfectly insulated to protect it from freezing. And how do you do that? You’ll find that out soon enough.

Discussed herein are ways to prevent your water heater from freezing. But before that, let’s look at ways in which cold weather can damage your water heater.

How can Cold Weather Damage Your Outdoor Tankless Water Heater?

The most exposed part of the outdoor tankless water heater is not the unit itself but the plumbing pipes that carry water to and from the heater. These pipes are vulnerable to freezing and thus the need to protect them from cold weather.

Cold weather can also damage the internal parts of the heating system. However, the good news is that you can thaw the frozen water heater by turning off the power, closing the gas and water shutoff valves.

If you suspect that your water heater is frozen, avoid using it at all costs. It is the only way to prevent further damages.

To protect the water pipes against extreme cold weather, all you need to do is cover them using pipe wrap insulation or heat them with a pipe heating cable.

How to Insulate the Pipes

1. Measure the length of the pipes you want to insulate

The first thing you need to do is survey all the pipes that you intend to cover. Get a pen, paper, and measuring tape. You’ll need them to measure and jot down the measurements of each pipe.

Measure the length of each pipe feeding into the tankless water heater and write everything down. For each pipe, ensure that you note the diameter next to the length. These measurements will help you know how much heating wire and insulating pipe tape you’ll require.

Ensure that you get measurements for all pipes on exterior walls and uninsulated basement areas, as all are vulnerable to freezing. If your house is on risers, bring a flashlight and a disposable crawl suit. Crawl to your crawlspace and check the pipes.

2. Purchase insulation for your pipes

Now that you have the measurements with you, what remains is deciding on the type of insulation you want and getting it from the store.

There are 2 choices to make here; You can choose to get either polythene insulation( a material similar to wall insulation, looks like black foam, that is explicitly made for insulating pipes) or pipe tape and heating wire.

Take the list of your measurements to your local construction store and buy enough insulation to cover all the pipes. The inside diameter of the insulation you get should match the outside diameter of your pipes.

Read the packaging label carefully since the length and interior diameter of the insulation is always listed there. It also always a good idea to have extra insulation on hand. You might need it.

The good thing about pipe insulation is that it comes already precut, making it easy for you to wrap it around the pipes with ease. You can also cut it to length with ease using a pair of scissors if needed.

3. Wrap the electrical heating tape around the pipes

Plug the heating tape into the nearest power source at the beginning of the pipe by your heater. Then, run this tape along the pipe, twisting it every 12 inches to make a spiral pattern.

Ensure that you secure the heater tape to the pipe after every few inches with the electrical tape. While doing so, don’t let the heater tape cross itself along the pipe.

Should you run out of the heater tape a few inches to the end of the pipe, don’t worry. The pipe will be fine since the rest of the heated water will prevent it from freezing.

4. Wrap the pipes with the insulation tape

Now that the heater place is already in place, it’s time to wrap the pipes with the insulation tape. To do it properly, find the vertical seam where the insulation in question is cut.

Then, dig your fingers into the seam and pull the insulation open. Next, attach the insulation to the pipe by pressing its interior around the pipe.

Repeat this process with all the pipes.

5. Secure the insulation with cable ties or duct tapes

To keep the insulation from sliding off the pipes, tie it securely using duct tape or cable ties. For the best results, wrap the tape around the base of the insulation 3 to 5 times and pull it tight.

You can also attach it by wrapping it around the pipe and threading it from one end of the tie to the other. Work your way up, cover the duct tape, or place a cable tie every 2 to 4 feet.

Repeat the process with all the pipes.

One important thing to note is that you should not pull so hard on your pipes when wrapping them with the insulation since you don’t want them to crack during the process. As long as the tape or ties keep the insulation in place, you’re fine.


Protecting the pipes that carry water to an outdoor water heater is very important. It is the best way of keeping the system in operation during cold weather. If you use an outdoor tankless water heater in your home, this guide comes in handy. We hope that it’ll help you keep your water heater working all year round.

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