DIY water heater: Cheap and easy way to get an unlimited supply of hot water

03/04/2022 / By Nolan Barton

Hot water comes in handy during winter season, especially if the grid goes down. In that scenario, you may need to boil water every now and then – or you could build your own device that can give an unlimited supply of hot water.

To that end, a man who calls himself Engineer775 has created a video showing how to make hot water using the thermal siphoning process.

For the uninitiated, thermal siphoning is a method of passive heat exchange based on natural convection, which circulates a fluid without the necessity of a mechanical pump. Convection refers to the transfer of heat by the movement of fluid between areas of different temperatures.

A thermosiphon is what you call a passively driven thermal management device that uses the motive forces of natural convection and conduction. The device uses these forces to create a cyclic fluid flow from areas of high heat to low heat and back.

In the video, Engineer775 used a coil, a stovepipe and some copper tubing for the thermal siphoning process. He also had a 40-gallon water heater and a few sticks to burn.

“This is a do-it-yourself [DIY] hot water. [It’s an] on-demand heater that could supply you [with] plenty of water — hot water, that is — in a grid-down situation,” he said. “I want to show you what you can do with some scraps, things that have been scavenged and things that have been thrown away.”

He bent the coil a certain way that made it look like a tiny pile of ropes and placed it inside the stovepipe.

“What I’m going to be doing is as the water comes into this hot coil, it will rise up in the coil and dump into the top of the water heater,” he said. “So I have this cold water from the drain and then the cold water goes and it hits the bottom of the coil and then it rises up.”

The stove temperature reached as high as 565 degrees during the process and you can hear the gurgling sound of hot water going to the top.

“Now that water was about 180 degrees. So, yeah, this can be a little dangerous, but you need hot water for your dishes or for laundry. And this thing is just pumping away,” Engineer775 said.

DIY solar-powered water heater

When it’s not winter and the sun is out, there are better ways to heat water off-grid. And one of the best and cheapest ways is to harness the power of the sun. (Related: Intro to building your own solar-powered water heater.)

The solar-powered water heating process makes piping hot water that you can plumb into your hot water heater.

The method is quite simple:

Find a used, broken traditional water heater. You can find one at landfills, building supply stores and local appliance shops.
Strip away all the bits and pieces until you are left with a bare tank.
Paint that tank completely black.
Place the tank in a wooden frame lined with Reflectix. Place a pane of glass on top – you can salvage one from an old window or sliding glass door.
Connect a hose into the tank and fill it with water. You can connect an output hose that gets pumped into your hot water heater.
Let that bake in the sun, and you will have piping hot water.

Be careful when using this method as it makes scalding hot water. Make sure you don’t burn yourself in the shower. (Related: Scalded by boiling water? Here are some treatments and home remedies that may help.)