Installation of the gas tankless water heater can be more complicated than that of tank heaters.
To install a gas tankless heater, you must inspect the gas, water, and electrical inlets to ensure that the system works properly.

Tankless water heaters are a simple, compact, and efficient way to get hot water to your home on demand. Moreover, the gas tankless water heater saves up to 70 percent of the yearly heating bill.

Gas Tankless water heaters can produce three to four times the BTUs of a conventional water heater, so you should verify that the thickness and length of the current gas line and meter can supply sufficient gas flow for unity.

Here we pick up the full guidelines in a few steps you can follow on how to install gas tankless water heater that will help you to install it without any hassles and crux.

Tools and equipment:

  • Power Drills
  • Screwdriver set
  • Reciprocating Saws
  • Pipe
  • Black Pipe
  • Pipe Insulation
  • Solder
  • Metal Ducts
  • Solder
  • Connectors and Gas fittings
  • Valves
  • Tankless Gas
  • Pressure-treated Lumber
  • Caulk and sealants

Remove your Old Water Heater

If there is an old water heater on the existing place, you have to remove this old water heater first. Before starting the water heater installation you have to contact your local gas provider about the size of your gas supply. Because a Tankless water heater usually needs more gas than other gas appliances.

After removing this old one, you need to turn off the gas and water pipe also shut off the supply valves, and drain the water from it.

Install a New Gas Line

Install the gas line is the first condition to install the tankless gas water heaters. If your current gas is accurately afforded to fulfill your water heater gas demand. Connect a valve with this existing gas line.

You can use a black pipe or flexible gas supply line to run a new gas supply line from the valve to the point where it can be attached easily to the gas line of your new water heater.

Install Gas Line - How to Install Gas Tankless Water Heater

Install New Water Lines

Now it is turn to install the new water lines entire your home from the water heater place. You have to tie both cold and hot water supply lines on the existing water lines with copper pipe.

Here you can use bell hangers to hold the pipes securely in place against your room wall. They will also help you to apply pipe insulation later.

You should clean the pipe connectors and fittings before soldering to remove oxidation.  Add a flux end of the pipes and join with the slip pipes. At last, heat the copper with solder and torch to join your pipes accurately.

Set the Water Heater

After completing the pipe installation, you can set up the water heater on your desired location. You should make a platform with 4 inches 2 lumber on the wall that will hold your tankless water heater.

Make sure the platform placed tightly on the wall. Otherwise, it will fall down due to the water heater weight.

Now you can place the water heater on this platform and set up it with screws.

Be careful to place and set up the water heater as if it doesn’t slip or fall down to make damage or unusable.

hot water heater installation

Connect to the Water Heater

This is time to connect the supplies line into the water heater. Firstly, you can connect the gas supply into the shut-off valve. Then connect both the cold water inlet and hot water outlet supply, as usual, the gas supply line.

After connecting the supply line and pipes you should turn on the valves and check leakage. If there is no leakage you can go forward of this installation process Or shut off the leakages.

Install the Vent

Installing the vent is an important step in Gas water heater Installation. Use heat-resistant silicone sealant to create a vent shaft for your water heater. First, make a shaft on this silicone board with a pencil or color pen.

Make the vent shaft hole with power drills and reciprocating Saws outside the marked line. Now it is ready to set up a vent pipe.

Install the interior flange from inside and run a section of this vent pipe through the flange opening section, then secure each section with the tabs. And from the outside, connect a small section of vent pipe with a vent hood

There is a PVC pipe vent in several water heater. This is also the same process to install the vent.

Install the vent

Turn on your Water Heater

Add all kinds of faucets on your home to complete the water heater installation process. Now you can turn on the gas supply line and water pipes. After a while turn on your faucets and check your water heater.

Before turn on the gas line and water supply, you should follow all kind of terms and procedure which is included by its manufacturer.

Is your water getting hot? If your answer is positive.  Then you are successful to install the Tankless Gas Water heater.


We think you have done the tankless water heater installation without any hassle or problem. If you are getting in trouble on how to install gas tankless water heater then we highly recommended installing your gas tankless water heater by a professional and licensed plumber as it is difficult and sometimes it makes the dangerous issue.