How To Install A Tankless Water Heater: A Step-By-Step Guide

how to install a tankless water heater

A tankless water heater is a perfect solution for anyone looking for an efficient and cost-effective way to heat their home’s water supply. Whether replacing an old water heater or looking for a more efficient option, a tankless water heater can provide you with hot water on demand. But how to install a tankless water heater?

Installing a tankless water heater can significantly improve your home’s energy efficiency and save money on your energy bills. It isn’t difficult but requires technical know-how and a few tools.

Here we will learn how to install a tankless water heater and the whole installation process.

How To Install A Tankless Water Heater: Gas Tankless Water Heater


Here are the steps on how to install a tankless water heater – 

1. Take out the current water heater

First, you need to know the size of the main gas. Connect a big pipe to the gas meter as this heater uses more gas than large furnaces. You can call the gas company to get the required information.

You can switch off the water & power supply to the current heater. In addition, turn off the valves to supply gas to the unit. You can drain & take out the heater from its mount before disposing of it in a recycle bin.

2. Fix new water & gas lines for the heater

If the existing gas line is in a suitable size, you can fix a tee and a valve or any of them. Then, use a black pipe to link the brand-new supply line near the gas line on the new gas tankless water heater. In addition, use a flexible gas supply line for this task.

You can use a copper pipe to connect existing water lines. Further, move the lines to the new tankless heater. If the system has an anti-siphon or checks valve, you may keep an expansion tank at the cold water inlet of the unit.

You can secure the pipes to the wall with bell hangers. In addition, you can utilize some pipe insulation.

Now, remove oxidants by wiping out the connectors & pipes. Add flux to the end of the piping, and attach it to the connectors before fusing with a torch. Make sure to heat the copper pipe before soldering.

3. Place the heater on a stand

Buy 2 pieces of lumber (with 4 inches) & create a platform. You can look for a well-ventilated spot in the room & place the stand. After that, put the new water heater on the platform.

4. Install the water heater

Please confirm if the water heater has the drain & purge valves. You can utilize the owner’s manual to attach the sediment trap & shutoff valve to the heater. Then, you need to link the gas supply line to the shutoff valve.

Securely fix the valves on heater to the water supply line, then inspect for any water leakage by turning the water supply on. If no leaks are found, execute the same process with the gas line. Once the process is completed, switch off the gas until the unit is entirely set up.

5. Fix the new vent

You need to look for the vent shaft of the unit & place some adhesive. Utilize silicone sealants that can handle the heat.

Then, add a connector & tighten it with a hose clamp prior to slipping on a section of the vent pipe. You can then place a retaining ring on the tube. After that, fold over the taps for extra security.

You can fix an elbow and make sure its mouth faces the same spot (outside) of the water heater vents. Then, bore a hole inside the wall that would serve as an outlet for the unit.

You must make the space and mark a circle on the outside wall with a vent thimble. Utilize a spade bit to make a 1-inch hole above the mark.

Create a vent hole by using a reciprocating saw. Remove sidings or shingles from the hole. Then, add silicone caulk on the end of the flange prior to pushing it into the opening. After that, tighten the assembly with screws (to the outer wall) & seal the fasteners with silicone.

Attach an interior flange to the inner wall, place the vent pipe through its opening, and use clamps to ensure the tube is in the right spot. Afterward, go to the outer wall and attach one pipe end to a vent hood. Finally, secure the siding or shingles around where the vent comes out of the wall.

6. Switch on the unit

Take out unwanted air from the plumbing & heater by running hot water from the faucet. After some time, switch off the water & connect the heater to a power supply.

Before switching on the gas, you must add insulation to pipe that carries hot water from the unit. You can also complete this stage by following the owner’s manual’s tankless water heater installation instructions.

How To Install A Tankless Water Heater: Electric Tankless Water Heater


If you are looking for a substitute for a gas tankless water heater, you can choose the electric model. Electric tankless water heaters are easier to set up and do not require gas combustion.

You need to know the setup requirements for an electric tankless water heater, as it works differently from other models. Review the owner’s manual periodically to keep up to date with this information. Additionally, purchase an electric heater suitable for your property before starting the installation process.

Here are the steps on how to install a tankless water heater – 

1. Disconnect the power & water supply

Turn off the power on the unit. Disconnect the incoming water supply line from the heater. Keep a container under the water bib to gather spills from the pipe.

2. Remove the water heater from the room

For an electric water heater, unplug the appliance from the wall outlet. Take out the plug of existing heater from the power source. As soon as it becomes free, dismount the unit & toss it into the garbage or recycle bin.

3. Connect the new unit

Even though you may be familiar with different techniques for mounting a tankless water heater, it is suggested that you place it in an upright orientation. Position your newly purchased heater and search for the optimal location to set it up. Once you have found the right spot, put the unit on a level surface and secure it with four bolts.

4. Connect the unit to the power & water supply

Clean the pipe that provides cold water & then attach the outlet of the water heater (on the left side) to the line for hot water. Go to the right side of the heater and link the cold water line to the cold water inlet.

Ensure to secure all the fixtures on both sides of the heater, then run all the hot water taps for 3 minutes. Once you have verified that there are no leaks, move on to the next step: link the unit to an electrical source.

Before connecting a black and red wire to the breaker, ensure that the power to the heater is switched off using the circuit breakers.

Employ a wire gauge to route the electric cable from the circuit breaker (in the primary electrical board) to the water heater. Attach the cable to the block terminal on the unit. Once all the connections have been secured, screw in the front panel of the heater.

5. Turn on the water heater

To deplete the air in the power lines, you should run the hot water taps for 3 minutes. After that, power up the circuit breakers in the main unit. Subsequently, you can activate the switch in the unit.

How To Install A Tankless Water Heater: Tips For Installing The Electric Tankless Water Heater

After understanding how to install a tankless water heater, it is wise to consider the following advice when installing an electric tankless water heater.

If you plan to install an electric tankless water heater, make sure it is equipped with an exhaust system with a wide diameter. It should work with a high-voltage steel flue. Before installation, confirm these features without seeking professional help.

When it comes to plumbing, it is recommended to use a union connector set so that you can easily disconnect. These pieces enable you to take out limescale from the heater without difficulty.

FAQs(Frequently Asked Questions) On How To Install A Tankless Water Heater

1. Can I install my own tankless electric water heater?

It is feasible to put in a tankless water heater by yourself, though it is unsuitable for those with a little DIY experience. There are various sizes and varieties of tankless water heaters, such as propane, natural gas, and electric, as well as single-room or whole-house versions.

2. What is the downside of a tankless water heater?

Besides the hefty initial fee, tankless water heaters have a few other drawbacks compared to tank-style water heaters, such as taking a long time to produce hot water. When multiple faucets are open simultaneously, the water temperature varies. Furthermore, it is impossible to access hot water during an electrical blackout.

3. Do tankless water heaters need special wiring?

The heater must be hooked up to an electrical circuit that is either 120 or 240 volts and is exclusive to it. Both voltages demand 8-gauge wire, and the portion that is visible in the area under the sink must be covered in a protective sheath.

Summary: How To Install A Tankless Water Heater


Installing a tankless water heater can greatly improve your home’s energy efficiency and save money on your energy bills. But how to install a tankless water heater? It isn’t difficult, but it requires technical know-how and a few tools.

You should be thrilled with the tankless water heater due to its mobility and energy-efficient properties. Consider trying to do the job yourself if you cannot afford to hire a professional to install your tankless water heater. Since the task necessitates expertise, you ought to enlist the help of a plumber or installer. 

To install a gas tankless water heater, detach the existing unit and put it on a new mounting. Make sure to verify any leaks on the device. Moreover, this guide is also relevant for models powered by electricity.

I hope this article on how to install a tankless water heater sounds helpful!

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