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How to Install a Tankless Water Heater?

If your water heater is due for replacement, the chances are that you may be considering making the switch to a new tankless model. Tankless water heaters are all the rave now thanks to their low energy usage, their relatively small size, and the considerable durability bump from older tanked models.

However, if you are at a crossroads about making the switch, rest assured that a capable tankless model constitutes a significant improvement to your hot water system. Tankless models bring more efficiency as they do not have to reheat water stored in the heater reservoir continually.

Nevertheless, if you have shopped around for a tankless model, you are already aware that these units are significantly more expensive. While a tankless electric heater can cost you anywhere from 500 to 800 bucks, the typical gas-powered one can amount to double that.

Furthermore, since tankless heaters are a lot more complicated than their tanked counterparts, they can often require special requirements that can considerably drive up the cost of the installation process. With these heater types, you may need to modify your preexisting home supply lines, and installing the unit yourself may be almost impossible.

However, if you are looking for a guide to installing your new tankless water heater yourself, this is the article for you. Here, we will take you through a step by step process to getting your heater set up and ready to fulfill your hot water needs.


How Tankless Water Heaters Work

Tankless water heaters are also called on-demand type heaters because they heat water instantaneously without the need for a storage tank. The heater sits in an idle mode without consuming any energy to achieve this hot water on-demand mode, until the adjoined faucet is turned on.

Once you turn on your water outlet in need of hot water, a flow sensing component of the appliance switches on the heater and begins to heat water. These heaters run the water through an electric filament or a gas burner to get it to the required temperature in a short while.

The heater shuts back down once your outlet is turned off. Since there is no storage tank to fill, tankless water heaters can provide an unlimited stream of hot water while eliminating energy wastage in standby.

Should You Install a Tankless Water Heater Yourself?

Whether you should install a tankless water heater yourself depends on the model, your experience level, and the current state of your home’s venting and piping systems.

While the number of users with successfully self-installed units is on the rise, it is not uncommon for the product manufacturers to attempt to dissuade buyers from DIYing their heater installation, and it’s for a good reason.

Installing a tankless water heater yourself comes can come with safety risks as well as the chance of voiding your product warranty.

An improperly installed unit can cause gas leaks in case of gas-powered heaters, or the risk of fire hazard from a faulty connection in electric models. Furthermore, for many tankless water heater brands, installing the unit yourself voids your consumer warranty immediately.

However, if you get a heater model that is significantly plug-and-play, and you have to required technical knowledge, you shouldn’t have any issues setting up the unit yourself. Nevertheless, for this to work, the heater’s requirements must match the preexisting venting, gas piping, line, and meter, or electrically configuration in your home.

Otherwise, you will need to revamp the set up in your home, and such advanced work is best left to a professional.

How to Install a Tankless Water Heater

#1 Permits and Building Codes

The first step when installing your new tankless water heater is to ensure that the installation parameters comply with all applicable permits and building codes.

Many localities in the U.S. enforce inspections both before and after installing a tankless heater. Furthermore, you will likely have to get several permits as well that includes those for gas piping regulations, electrical, and mechanical permits. You may also have to meet certain standards for carbon emissions as well as specific venting requirements.

Even more, you must ensure that the location of the appliance within your home matches the appropriate local and state building codes.

These permits and inspection rules may vary significantly depending on your current jurisdiction. To avoid any infractions, check with documentation from your local authority before getting started.

One advantage of opting for a professional install instead of DIY is that a certified plumber will already be well acquainted with all the necessary regulations.

#2 Checks and Caution

Depending on the design of your new tankless water heater, the unit may require supply specifications that are vastly different from what you already have in your home. To reduce the chance of any hazards, check to ensure that your home setup matches what the heater needs to function correctly.

Gas-powered tankless heaters typically require gas supply lines with larger diameters than what you will need for a traditional tanked model. Hence, if you are upgrading from a tank unit, you may need a professional revamping of your gas lines before installing the new heater.

Similarly, electric tankless water heaters generally require a power supply with a significantly higher voltage than you will need with a traditional electric unit.

Furthermore, with a tankless heater, you will need a category two or higher stainless steel flue, while a gas-powered electric unit will also require a more extensive exhaust system.

Another important check is to look for a union connector set on your water supply line. If you don’t already have one installed, we recommend you look into getting it. A union connector adds bypass capability to your supply line, allowing for easy de-liming and other forms of maintenance.

#3 Removing Your Old Unit

Once you have met all the requirements for your new heater, you can now begin the installation process proper, but first, you have to remove your old unit with the following steps.

  • First, switch off the main water line that supplies water into your house
  • Then proceed to disconnect the old water heater from the water supply line. Since you still have some remaining water in the system, you may have to place a container under the heater’s water inlet to prevent any spills
  • Next, disconnect the energy source. For gas-powered heaters, you can achieve this just by closing the supply valve. For electric heaters, unplug the device from the mains, and you are good to go.
  • After verifying that you have disconnected all supply and venting lines, dislodge the old heater from its mount and dispose of the unit per the prevalent regulations in your locality.

#4 Mounting the New Unit

Now you are ready to mount your new tankless water heater.

  • Remove the heater and other hardware from the carton and have everything else you need ready at hand
  • Next read through the instructional manual to acquaint yourself with any model-specific quirks
  • Figure out the best location for your heater while adhering to the appropriate building codes
  • Mount the unit on the wall or under the sink per the OEM guidelines
  • Finally, ensure that the weight of the appliance is fully supported and add extra support if needed.

#5 Connecting the Supply Lines

Once you have the heater securely mounted, you can then proceed to hook up all the necessary connections.

  • First, for gas-powered units, install the vent ducting and connect it appropriately to your home venting system. Tankless water heaters require a category two or larger stainless steel flue.
  • Connect the water supply line to the heater and bolt it on firmly
  • Next is the energy source. Hook up the heater’s gas supply line to the nearest wall gas outlet and open the valve. For electric units, connect the plug to a wall socket. For gas-powered heaters, you also have to light up the pilot per the manufacturer’s guidelines.
  • Turn on the main water supply line to restore supply to your home

Use the hot water knob on any connected faucet or showerhead to begin enjoying your new tankless water heater.

Installation Q and A

Q: Do I get hot water immediately after completing the installation process?

A: Yes. However, every tankless water heater has a lag of a few seconds during operation. Since the heater does not have any hot water in storage, a short lag is typical as the heater works to get the water to the required temperature. The extent of the delay depends on the power of your heater, and the temperature rise.

Q: Can I use hard water with a tankless water heater?

A: Yes. However, irrespective of the type of heater you have installed in your home, it is always advisable to install a home water softener unit if you are dealing with hard water. Using hard water without a softener can lead to deposit buildup in both tanked and tankless systems. This buildup can, in time, lead to heater malfunction as well as accelerated wear.

Q: Can I use a recirculating pump with a tankless water heater?

A: Yes, but it will lead to a significantly higher energy bill from the added energy usage in standby.