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Best Tankless Water Heater Flush Kits of 2023

Flushing your tankless water heater shouldn’t be a draining job. These kits can make it much easier.

Water heater manufacturers usually recommend their units be flushed out and cleaned once a year. This will remove any build-up of minerals such as calcium, which can restrict the flow of water if left unchecked.

Flushing your water heater is a straightforward task but choosing a flushing kit can be more of a challenge. To help you decide, we have created this list of the best tankless water heater flush kits available today.

We have reviewed these flushing kits based on the quality of their components, price, and versatility.

Our Top Picks

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Product Comparison Table

Product Image of the My PlumbingStuff - Tankless Water Heater Flushing Kit - 32-ounce J.C. Whitlam FLOW32 Flow-Aide System Descaler - Zoeller 42-0007 Floor Sucker Pump - 5-Gallon Bucket - User Instructions - Safe to Use
Best Pump
My PlumbingStuff Tankless Water Heater Flushing Kit
  • First-grade plastic bucket
  • Powerful Zoeller floor sucker pump
  • Includes a quart of descaler solution
Product Image of the Whitlam Flow-Aide Descaler PLUS Kit
Best for Multiple Uses
J.C Whitlam Flow-Kit
  • 350 GPH pump
  • Includes eco-friendly descaler
  • Can be used on multiple appliances
Product Image of the Rheem RTG20124 Flush Kit - Tankless Gas Water Heater
Easiest Setup
Rheem Tankless Flush Kit
  • Easy-to-connect rubber hose
  • Works effectively with white vinegar
  • Large 5 gallon bucket

Product Reviews

Here are 3 excellent tankless flush kits to consider.

1. My PlumbingStuff Tankless Water Heater Flushing Kit

Best Pump

If you’re new to flushing your tankless water heater, this kit can make the job easier. It includes everything you need to quickly set the kit up and start flushing any heater from major manufacturers such as Rinnai.

The kit comes with a 5-gallon first-grade plastic bucket. It also features two 5-foot hoses which can be easily connected to the valves. The hoses have specialized “ports” which allow you to connect them to pipes without disconnecting the unit.

The pump is a Zoeller floor sucker pump, which is very strong and durable. It can be used fully or even partially submerged. You will also receive instructions and technical details.

The kit includes a quart of Flow-Aide System Descaler. The descaler is a strong, environmentally-friendly solution that quickly breaks down any build-up in the unit.

Photo of the My PlumbingStuff Tankless Water Heater Flushing Kit

What We Like

Large Bucket

The bucket is the perfect size for the amount of cleaning solution you need. It is also a good size for all types of tankless water heaters. It’s recommended that you use 4 gallons of solution in the bucket.

Strong Pump

The pump is small but powerful and can be used even if it isn’t fully submerged. Many users praised the pump, saying it is top quality.

Hoses Can Be Easily Attached

The hoses are strong and durable with a steel outer casing. Customers were very pleased with how easily they were attached.

Kit Includes a Descaling Solution

You receive a quart (32 ounces) of Flow-Aide System Descaler. The fluid in this descaling kit is a non-hazardous, biodegradable solution that dissolves scale, rust, mud, and lime.

What We Don't Like

Instructions Could Be More Detailed

Some customers criticized the instructions, saying they were missing some steps. Others said they weren’t detailed enough. Many of these customers instead used online instructional videos or other guides.

Product Specs

Weight 14.5 pounds
Hose length 5 feet
Size Full size
Bucket capacity 5 gallons

2. J.C Whitlam Flow-Aide Descaler Kit

Best Kit for Multiple Uses

If you want a flushing kit for more than your tankless water heater, this is it. The kit includes two rubber hoses, a pump, a 3.5-gallon bucket, and a Flow-Aide System Descaler.

The bucket isn’t as large as we would like, but it still does its job. The descaler is very strong but environmentally friendly; you won’t need to use much of it.

The kit includes a 350 GPH (gallons per hour) pump, so you can imagine how quickly it will get the job done. It is a rather small pump, but it fits perfectly into the small bucket.

You can also use the kit with other appliances, such as heat exchangers, vacuum pumps, and ice machines. It quickly dissolves and removes lime, scale, rust, and other types of build-up, keeping appliances running smoothly and helping you save energy.

What We Like

The Kit Includes a Descaler

The kit includes 32 ounces of the Flow-Aide System Descaler. It quickly removes any build-up within your unit and is non-toxic and eco-friendly.

Strong Pump

The 350 GPH pump is small but mighty. It will quickly move your cleaning solution from the bucket and through the unit. Customers were very pleased with the pump quality.

Can Be Used on Several Appliances

If you have multiple appliances that require flushing or cleaning, this is an even better investment. You won’t need to purchase separate kits, pumps, or hoses to perform the same task on a different appliance.

What We Don't Like

Hoses Aren’t as Durable as Expected

The hoses are made of rubber and aren’t as durable as we would like. Some customers complained of them leaking. Others users said they only leaked if they weren’t attached properly.

Product Specs

Weight 8.6 pounds
Hose length 5 feet
Size 15 x 10 x 15 inches
Bucket capacity 3.5 gallons

3. Rheem Tankless Water Heater Flush Kit

Easiest Setup

If you’re looking for a kit that is easy to set up, this might be ideal. The kit includes easy-to-follow instructions to help you get started.

You also receive a pump, two hoses, and a bucket. The bucket will hold 5 gallons, perfect for any cleaning solution you use. Some customers revealed that they only used about 2 gallons of white vinegar, and some even reused it later.

The hoses are made of rubber but they connect easily to the isolation valves of the tankless heater. Some customers weren’t very happy with the rubber hoses, which they felt resembled washing machine hoses.

The pump will circulate 7 gallons per minute through the heater to eliminate the scale and lime. This kit is compatible with all types of tankless water heaters. It could even help to prolong the life of your heater.

What We Like

Easy Instructions

Customers praised the kit for its detailed and easy-to-read instructions. While most kits include a guide, they sometimes skip a step. That won’t be a problem with this one.

Connects Easily

You can start the flushing quickly as the hoses connect easily to the valves. Customers said they were surprised at how quickly they got started.

Large Bucket

The bucket holds 5 gallons, which is great for cleaning as it is a good amount of solution. Customers have said they used about 4 gallons of white vinegar and ran the pump for about an hour.

No Need For Specialized Solutions

This kit was designed for white vinegar only and it does a great job. This means you can save money by not purchasing a specialized cleaning solution. White vinegar is an inexpensive staple in many homes thanks to its versatility.

What We Don't Like

Rubber Hoses Could Be a Problem

Some reviewers complained about the quality of the hoses. They didn’t leak but customers felt they were overpriced.

Product Specs

Weight 13.35 pounds
Hose length N/A
Size 15.4 x 12.7 x 12.4 inches
Bucket capacity 5 gallons

Product Comparison Chart

Product Award Weight Hose length Size Bucket capacity
My Plumbingstuff Flush Kit Best Pump 14.5 lbs 5′ Full size 5 gal
J.C Whitlam Flush Kit Best For Multiple Uses 8.6 lbs 5′ 15″ x 10″ x 15″ 3.5 gal
Rheem Tankless Flush Kit Easiest Setup 13.35 lbs N/A 15.4″ x 12.7″ x 12.4″ 5 gal

Do You Need a Flush a Tankless Water Heater?

Your local water quality directly affects how often you need to flush your heater. It could be anywhere from every six months to annually (1).

Compared to traditional heaters, a tankless water heater is more vulnerable to mineral build-up (calcium and magnesium). In regular tank water heaters, the build-up is usually at the bottom of the tank, which shouldn’t prevent the heater from working properly.

However, in a tankless unit, the build-up forces the unit to work harder. In time, this can damage the heater’s components.

Hiring a professional whenever you need to descale your unit can become very expensive. Flushing kits aren’t cheap either but they will eventually pay for themselves. If you’re a DIY kind of person, a flushing kit will undoubtedly come in handy.

How to Choose a Tankless Water Heater Flush Kit

A good flushing kit typically has two main qualities.

Includes the Necessary Parts

To perform effectively, a hot water heater flush kit needs to include the necessary parts. The best kits will include a fairly large tank or bucket, which could be anywhere between 3 and 5 gallons.

This bucket will hold the water heater cleaning solution. You can buy specialized cleaning solutions or you can use white vinegar.

A submersible pump is another important feature. The pump is submerged in the bucket and helps circulate the cleaning solution throughout the heater. Obtaining these as part of a kit is important because you can be sure the pump will fit the bucket.

The final essential part of a maintenance kit is two long hoses. These should ideally be 5 feet long so you can easily connect the kit to the heater unit.

These parts are designed to help you easily clean the internal parts of the heater. Alternatively, you can use a garden hose, a bucket, and a separate pump. However, this could make the job more complicated as you will need to make sure everything fits properly.

Works on All Types of Units

Another major benefit of the best flush kits is that they are universal kits and can be used on all heater models. Buying a kit and discovering that it won’t work on your unit can be frustrating and a waste of money!

Like conventional tank water heaters, a tankless heater can be powered by gas or electricity. A good kit will be able to work on both of these.


What Happens if You Don’t Flush Your Tankless Water Heater?

Depending on the quality of your water supply, failing to flush your tankless water heater can cause a gradual buildup of mineral deposits in the heater’s pipes. In time, this inhibits the movement of water through the unit and reduces its efficiency. It can even cause damage to the heater as it is forced to work harder to compensate.

What Size Pump do You Need to Flush Your Tankless Water Heater?

Each of the kits in our list includes a pump that will be suitable for flushing your tankless water heater. The size of the pump is less important than how powerful it is. Generally, pumps designed for this purpose possess about 1/6 horsepower; anything more powerful is unnecessary.

How Much Does it Cost to Flush a Tankless Water Heater?

You should expect to pay about $150 for a water heater flush kit, which will include everything you need to flush the unit. Once you own the kit, future flushes will only require some additional fluid; you can reuse the pump for as long as it continues to work.

Can I Flush My Tankless Water Heater Myself?

Yes, it is possible to flush a tankless water heater by yourself, and manufacturers recommend you do so yearly. It is not recommended to flush the water heater before turning off the electricity and the gas since doing so may cause the appliance to become damaged.

Before attempting a heater flush, you should always open the unit and use a non-contact electrical tester. This confirms that the power has been turned off. If your device is powered by more than one energy source, this step is necessary.

How Often Should Tankless Water Heater be Flushed?

Tankless water heaters should ideally be flushed at least once per year. Since a flush is required for the build-up of minerals inside the unit, people who live in areas with hard water might be required to flush their tankless water heater even more often.

Can I Use CLR to Clean My Tankless Water Heater?

Yes, you can use CLR to clean your tankless water heater. Calcium, lime, and rust are the three components that makeup CLR. All three of these chemicals tend to accumulate over time on surfaces that are in constant touch with water.

CLR cleaner is an excellent option for cleaning your water heater since it eliminates the need for scrubbing by breaking down the minerals that accumulate at the bottom of the heater. CLR can be purchased in a variety of sizes, including spray bottles as tiny as one ounce and containers as large as one gallon.

Do Electric Tankless Water Heaters Need to be Flushed?

Yes, electric tankless water heaters need to be flushed. Regular flushing is required of both electric and gas tankless water heaters. But it is crucial to keep in mind that the processes for doing so are completely distinct from one another.

For electric heaters, you will most likely simply need a screwdriver and a wrench, both of which are likely already in your possession.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.