Tankless Water Heater Expansion Tank- Do I Need an Expansion Tank

In addition to providing on-demand hot water, tankless water heaters are becoming increasingly popular. Although many tank-style water heaters have thermal expansion tanks, you may be wondering about tankless water heaters.

Do they require an expansion tank? A tankless water heater expansion tank is an excellent choice sometimes to use. But here there are some points to keep in mind.

Does a tankless water heater need an expansion tank? Do I need an expansion tank in a tankless water heater? Both of these questions are asked by people. Down in this post is a complete guide for all of you.

The answer is NO. According to section 608.3 of the 2018 International Plumbing Code (I.P.C.), tankless water heaters do not require a thermal expansion tank when no water storage device is used. There are, however, some exceptions.

Tankless water heaters used with recirculating systems or tanks must have an expansion tank to control thermal expansion in closed systems. Tankless water heater systems do not apply to most homeowners. So, in this view expansion tank on the tankless water heater is not a great idea.

Expansion Tank for Tankless Water Heater

Adding a tank to a tankless water heater is not an easy task. You should always consider installing an expansion tank if you have a ‘closed-loop system’ caused by a pressure regulator or check valve installed in the house’s water supply line.

Home water pressure is often compared to high blood pressure. Negative consequences usually do not occur immediately. Nevertheless, excessive stress can wear everything in your plumbing system down over time.

Water leaks occur most often in the toilet fill valves, supply lines, and solenoid valves in washing machines, dishwashers, and icemakers.

Note: Also watch this complete vidoe for expansion tank for Tankless Water Heater

Why Use an Expansion Tank?

There is a greater risk of premature failure with these systems under high water pressure. If you have excess pressure over 80 P.S.I. supplied to your home by the city water, Expansion tanks alone cannot correct this problem.

Its job is to reduce stress (P.R.V.). If you have a P.R.V. or check valve, a thermal expansion tank will provide you with pressure between 40 and 80 P.S.I.

The thermal expansion causes constant changes in force in a closed-loop system. You may be required to have an expansion tank regardless of water pressure in your city to pass a plumbing inspection – such as you would receive when installing a new water heater.

Currently, all new homes in Frisco, Texas, must have a P.R.V. and expansion tanks. As of the time of writing, an expansion tank must also be installed on new or replacement water heaters in Little Elm, TX, due to the check valves on the water meters.

For the applicable plumbing codes in your area, check with your city’s plumbing inspector. A water heater safety tank can be a perfect choice.

Water Heater Expansion Tank Purpose 

Most people ask a question about what does a water heater expansion tank do? The main aim of using an expansion tank is to make a choice valuable for every one of you. The main objective is to use a tank to store it for the person you wanted to use anytime.

On the other hand, it is a beautiful choice for home or office usage when you need it. So, use a tankless water heater with a storage tank and make your life enjoyable. water heater expansion tank purpose is similar to this.

It’s not always necessary to use a thermal expansion tank. Expression tanks are usually required to control the pressure inside your tank water heater, especially in municipal water supply systems.

A closed plumbing system means a check valve or backflow preventer that prevents water pressure from building back into the central water supply system.

Expansion Tanks and Tankless Water Heaters

As hot water is generated on-demand in tankless water heaters, the water is not stored. In other words, when you open a hot water faucet, hot water is produced by the water heater. Water heaters cease to have hot water when a tap is closed. An expansion tank for a tankless water heater can be used in this way.

A thermal expansion tank is generally not necessary with a tankless water heater (electric or gas). Because tankless water heaters produce hot water only as needed.

The tankless unit begins to have hot water when the hot water supply is turned on. Using this method, you do not need a thermal expansion tank to ensure that your plumbing system doesn’t expand.

In the event of the hot water tap being turned off, the plumbing system is closed. As a result, since the tankless unit does not produce hot water, thermal expansion tanks are unnecessary.

In tankless water heaters without a storage tank for hot water, expansion tanks are not required by the building code.

Water heaters usually need them to extend their life and reduce the risk of ‘overworking’ your plumbing system. The following two examples will help clarify this further:

Tankless water heaters sometimes need a thermal expansion tank. It is not uncommon to see both tankless and tank-style heaters used together in large houses with high hot water demand.

When Does a Water Heater Need an Expansion Tank?

If a residential plumbing system is closed, I.P.C. requires a thermal expansion tank. Installing a thermal expansion tank might be necessary if you have a check valve or a backflow prevention device on your main water line.

An additional device acts as a backup to prevent excessive pressure build-ups over time, which can cause potentially serious (as well as costly) plumbing problems. Water from the heater runs into the expansion tank, reducing pressure to a safe and manageable level.

Read the next post! Best Tankless Water Heater for RV

Tankless Water Heater (Electric or Gas) Using a Storage Unit

Tankless water heaters generate hot water as needed or on-demand. When hot water is available on-demand, it means that it arrives at the open tap as soon as the cooled water in the hot water piping is released and warm water is produced.

It requires about two to three minutes, depending on the distance between the fixture and the tankless water heater. Opened hot water taps to heat water.

Unlike conventional tank water heaters, tankless water heaters produce and store hot water without adding a thermal expansion to the plumbing system. Gas water heater expansion tank is recommended over the other types.

Water Heater Expansions Size

The size of a water heater expansion tank is somehow a critical task to complete. The reason is that it needs complete attention rather than only choosing some points and making it excellent for you.

There is not a hard and fast rule. But you can estimate it by using your 0plumbing system anytime you wish. If you have a tank for 50 gallons, you can use an expansion tank of 2 gallons. And the same is the case for further.

Note: Looking for the tankless water heaters in 2023? Here are some of the top rated electric tankless water heaters which you can rely on!

What Are The Requirements For Expansion Tanks?

Water heaters (including tankless models) with potential thermal expansion problems need to be fitted with expansion tanks under the International Plumbing Code of 2012. The backflow prevention device or check valve must only be installed in homes with closed plumbing systems.

Several revisions have occurred and will continue to occur as plumbing systems and components evolve.

In What Ways Do Thermal Expansion Tanks Benefit You?

The water pressure within the plumbing system is controlled and reduced using thermal expansion tanks. The high pressure in your water heater can damage water valves, weaken the joints or cause the water heater to wear out sooner.

Home-related issues such as these can be problematic as well as costly to fix. Water heater thermal expansion tank has versatile advantages.

Thermal expansion tanks incur an additional cost upfront but can often save you money over time. Your water heater will run efficiently for years without severe and costly plumbing repairs due to uncontrolled water pressure.

How to Install An Expansion Tank On A Gas Water Heater?

Installing an expansion tank is very easy, and there are only some necessary steps to keep in mind. Some tools are mandatory to use. See the video given below for more information:

What Does The Expansion Tank Water Heater Cost?

The cost of an expansion tank water heater depends upon the gallons per liter from a tank. A tank with s gallons costs $20 to $40. And a tank with 4 gallons costs only $50 to $70.

Final Verdict

The question of instant hot water versus continuous hot water has become increasingly confusing over the years as water heater manufacturers have attempted to resolve it. Recirculation systems are standard features in many tankless water heaters.

Due to their limited heat output, while closed, I expect tankless water heaters and expansion tanks may become part of the building code in the next few years. So, using a tankless water heater expansion tank is a wise idea if used ideally. Finally, the tank and tankless water heater combination is a positive vibe for many people.

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