Best Tankless Water Heater Flush Kits of 2021

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

Have you noticed a decrease in hot water flow? If you haven’t flushed your tankless water heater recently, the decrease could be caused by a build-up of scale within the 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. It’s an easy job if done with the right equipment.

We’ve reviewed the best tankless water heater 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
  • 5-gal first-grade plastic bucket
  • Powerful Zoeller floor sucker pump
  • Includes a 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 several appliances
Product Image of the Rheem RTG20124 Flush Kit - Tankless Gas Water Heater
Easiest Setup
Rheem Tankless Flush Kit
  • Easy-to-connect rubber hose
  • No specialized solutions required
  • Large 5 gal. bucket

Do I Need a Tankless Water Heater Flush Kit?

How often you need to flush your heater depends on local water quality — it could be every six months or annually (1).

Compared to regular heaters, a tankless water heater is more vulnerable to mineral build-up (calcium and magnesium). Also, in regular tank water heaters, the build-up usually happens at the bottom of the tank, which shouldn’t compromise the functionality of the unit.

In a tankless unit, however, the build-up forces the unit to work even harder. This could damage the components of the heater.

Calling for professional help whenever you need to descale your unit can become expensive in the long haul. Although flushing kits aren’t cheap either, they can pay for themselves after a while. If you’re a do-it-yourself type of person, we’re certain this will come in handy.

How to Choose a Tankless Water Heater Flush Kit

A good flushing kit typically has two main features.

Comes with the Right Parts

For the best performance, a flush kit has to come with the right parts. The best type of kit will come with a fairly large tank or bucket. This could be anything between 3 and 5 gallons.

The bucket will hold the cleaning solution. You can buy specialized cleaning solutions, or you can use white vinegar.

A submersible pump is another important feature of a kit. The pump is submerged in the bucket and helps to circulate the cleaning solution throughout the heater. This also makes for a great kit because you’re sure the pump will fit the bucket.

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

All these parts are designed to help you easily clean the internal parts of the heater. You can also use a garden hose, a bucket, and a separate pump. However, it might make the job a little more complicated since you have to make sure everything fits.

Can Be Used on All Types of Units

Another important feature of a flush kit is that it is a universal kit that can be used on all heater models. Purchasing a kit and then finding out it won’t work on your unit can be frustrating — not to mention a wasted expense.

Similar to regular tank water heaters, a tankless can be powered by gas or electricity. A good kit will be able to work on either of these.

The Best Tankless Water Heater Flush Kits of 2021

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 might make the job a little easier. It comes with everything you need to quickly set the kit up and get started.

The kit comes with a 5-gallon first-grade plastic bucket. It also comes with two 5-foot hoses which are easy to connect directly to the valves. The hoses have specialized “ports,” which enables you to connect them to pipes without disconnecting the unit.

The pump is a Zoeller floor sucker pump. Zoeller pumps are super strong and durable — it can even be used fully or only partially submerged.

With the kit, you will also receive instructions on how to get started and technical details.

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

Why We Love It

Large Bucket

The bucket is the perfect size for the amount of cleaning solution you’ll need. It also fits well to all types of tankless water heaters. It’s advised that you use 4 gallons of solution in the bucket.

Strong Pump

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

Hoses Can Easily Be Attached

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

Kit Includes a Descaling Solution

You get a quart (32 ounces) of Flow-Aide System Descaler. The descaler is a non-hazardous, biodegradable solution which dissolves scale, rust, mud, and lime.

Keep In Mind

Instructions Could Be More Detailed

Customers commented on the instructions, saying they felt it was missing some steps. Others said it wasn’t detailed enough. Many mentioned they found instructional videos online or used other guides.

Additional 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’re looking for a flushing kit to use for more than just 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’d like, but it still does the job smoothly. And, the descaler is very strong but safe for the environment; you don’t need to use a lot.

The kit comes with a 350 GPH pump. GPH means gallons per hour, so you can imagine how quickly it will get the job done. However, it’s a rather small pump, although it fits great into the small bucket.

You can use the kit with multiple other appliances, such as heat exchangers, vacuum pumps, and ice machines. It quickly dissolves and removes lime, scale, rust, and other potential types of build-up. Then, it restores the efficiency of your tankless water heater so you can continue to save energy.

Why We Love It

The Kit Includes a Descaler

The descaler included is the same as our top product. You get 32 ounces of the Flow-Aide System Descaler. It works fast at removing 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 get your cleaning solution from the bucket and through the unit. Customers were very pleased with the quality.

Can Be Used on Several Appliances

If you have multiple appliances which require flushing or cleaning, this could be worth the investment. You won’t have to purchase separate kits, pumps, or hoses to do the same job on a different appliance.

Keep In Mind

The Hoses Aren’t as Durable as Expected

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

Additional 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 which is easy to set up, you might just love this. The kit includes easy-to-follow instructions to help you get started.

You also get a pump, two hoses, and a bucket. The bucket will hold 5 gallons — perfect for any cleaning solution you might use. Many customers revealed they only used about 2 gallons of white vinegar, and some even reused it another time.

The hoses are made of rubber, but they connect easily to the isolation valves of the tankless heater. Again, customers weren’t too happy about the rubber hoses, as they felt they resembled washing machine hoses.

The pump will circulate 7 gallons per minute through the heater to eliminate all the scale and lime. This kit is compatible with all types of tankless water heaters. And, it could even help to prolong the life of your heater, as it cleans it out very well.

Why We Love It

Easy Instructions

Customers praised the kit for the detailed and easy-to-read instructions. While most kits come with a guide, they tend to be missing something. You don’t have to worry about that with this one.

Connects Easily

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

Large Bucket

The bucket, which holds 5 gallons, is great for cleaning since you can fit a good amount of solution in there. Customers have said they used about 4 gallons of vinegar and ran the pump for about an hour.

No Need to Purchase Specialized Solutions

This kit was designed for vinegar use 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 pantry staple in most homes since it has so many uses.

Keep In Mind

Rubber Hoses Could Be a Problem

Some reviewers had a few complaints about the quality of the hoses. They didn’t leak, but customers felt it was overpriced.

Additional Specs

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

Tankless Water Heater Flush Kit 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

Headshot of Peter Gray

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.