Ask Brian: How to Install a Tankless Water Heater



Ask Brian is a weekly column by Real Estate Expert Brian Kline. If you have questions on real estate investing, DIY, home buying/selling, or other housing inquiries please email your questions to askbrian@realtybiznews.com.

Question from Mike in ID: Hello Brian. Last week our hot water tank unexpectedly stopped working. Well, may not completely unexpectedly. Over a couple of months I noticed the water was taking a long time to heat up after someone showered. I turned up the thermostat so not as many gallons of hot water would be used. Last week, when it stopped working altogether, my neighbor showed me how to change the electric heating element. Yay! We have hot water again for less than $75. However, the neighbor also pointed out the heater was manufactured more about 17 years ago. He convinced me that the entire heater should be replaced before it quits working again. He also mentioned I might want to consider installing an on-demand water heater. As you probably figured out, I’m no great mechanic. How big of a project and how would I go about converting to an on-demand water heater?

Answer: Hi Mike. Converting from a 40 gallon tank (or similar) to a tankless system isn’t terribly difficult but it’s not a beginner’s project either. It involves both basic electrical and plumbing skills. Assuming you’re going to keep it in the same location, this is more or less an intermediate level DIY project. If you already have all of the tools and materials, it should take between 3 and 4 hours. If you get your neighbor’s help, it might take as little as two hours. If you’re planning to move the heater to another location, it will take days because you’ll have to run new electric circuits and plumbing lines in the walls or under the house.

However, if you keep it in the same place, the basic electrical and plumbing is already there. Not only are you going to lower your energy bill, but also a tankless system takes up about 15 cubic feet less space. The first thing you need to do is shut off the water and electricity to your existing tank. Your main electrical box should have a dedicated circuit to the heater so that you don’t have to shut off the electricity to the entire house. But you might have to shut off the main water supply to the entire house. There’s probably a cold water valve at the hot water tank but now is a good time to shut off the main supply and replace the valve at the water tank.

Once you’re sure the electricity and water are off, you need to drain water from the lines and tank. If you have a water valve in the house that is lower than the one at the tank (maybe a bathtub or basement valve), open both the hot and cold water valves to drain water out of the lines. Next, use a garden hose to drain the water out of the existing tank to somewhere appropriate (often outside). Once the tank is empty, you want to disconnect the electric and plumbing lines from the old tank and remove the tank from where it is.

Now, you should be ready to install the new tankless water heater. The instructions that come with the tank or someone at the hardware store can tell you what other hardware you need besides what comes with the new heater. This would things be like the valve that you should replace, a new hose to connect the cold water supply to the tankless heater, a new hose connecting the hot water to the house plumbing, an a few things you might already have like new electrical nuts and plumbing tape.

If you have everything that you need, you’re ready to install the tankless heater to the mounting surface. The new unit should come with instructions for this. Assuming it’s mounting to the wall, be sure it’s properly secured to the wall studs.

Next, you reconnect the cold water supply line to the new heater. This is where you might need some help from the people at the hardware store to make sure you have the correct connecting line. It could be copper (requires soldering), a flexline, or something else to meet local code. You might also need adapters to connect to both the supply line and house plumbing. Do the same thing to connect the hot water side of the heater to the house plumbing. Wrap Teflon tape around the threads before you make the connections.

At this point, all that should be remaining is connecting the electrical. One thing you should do when you purchase the tankless heater is make sure it is compatible with the existing electrical service (240 volt or 120 volt).

Mike, here are a few other things to consider when making the decision to convert to a tankless system. The U.S. Department of Energy estimates electric tankless heaters save $44 per year (natural gas is estimated to save $108 annually). Be sure to select a system appropriate for your needs. If you run a shower and the washing machine at the same time, you will need about 4.5 gallons per minute from the water heater.

This article deals with locating the new system at the same location as the old tank. Generally, that is the best location both for cost of installation and energy efficiency. If a different location is needed, ensure that the water will remain hot while traveling through the house plumbing even during the coldest season. There is a direct correlation between the heater’s performance and where it is. For example, installing it closer to the demand source ensures that less water goes to waste. Finally, ensure that your water heater is located in a safe place that is convenient for future servicing. Be a law-abiding citizen by installing your tankless water heater according to your State or City’s local codes.

Mike, selecting an on-demand water heater is a wise choice. Although the initial cost is more than a system with a tank, you’ll lower your energy costs for years to come. Just as importantly, you’ll be using less energy, which is always good for our environment. Please comment with your thoughts and experiences about converting to a tankless water heater as a DIY project or any other DIY project. Our weekly Ask Brian column welcomes questions from readers of all experience levels with residential real estate. Please email your questions or inquiries to askbrian@realtybiznews.com.

Author bio: Brian Kline has been investing in real estate for more than 35 years and writing about real estate investing for 12 years. He also draws upon 30 plus years of business experience including 12 years as a manager at Boeing Aircraft Company. Brian currently lives at Lake Cushman, Washington. A vacation destination, near a national and the Pacific Ocean.