Ever wondered why your tankless water heater isn’t performing like it used to? Maybe your hot water takes forever to arrive, or the pressure’s just not what it once was. If that sounds familiar, you’re probably dealing with mineral buildup—a silent killer of efficiency in these compact systems. Knowing how to descale a tankless water heater can save you from costly repairs, skyrocketing energy bills, and the headache of cold showers. In this article, we’ll break down the no-hassle way to descale your unit, what tools you’ll need, and how often to do it—all in plain, simple terms. Let’s dive in and keep your hot water flowing like it should.
Why Do Tankless Water Heaters Need to Be Descaled?
Although tankless water heaters accumulate scale more slowly than traditional tank models, the build-up of minerals over time can still have a significant impact on performance. As the scale settles around the heating elements, it reduces their effectiveness, forcing the unit to work harder to heat water. This increased workload results in higher energy consumption and reduced efficiency. In addition to wasting energy, the buildup can eventually restrict the flow of water, leading to issues like fluctuating temperatures and reduced water pressure. If this mineral buildup is left unaddressed, it can even start to damage the internal components, including the heat exchanger. Over time, this can wear down the walls of the unit, potentially causing the need for costly repairs or a full replacement. Regular descaling is essential to maintain your tankless water heater’s efficiency and longevity, ensuring it continues to provide reliable, on-demand hot water for your home.
Tools You’ll Need to Descale Your Tankless Water Heater
Descaling your tankless water heater doesn’t require a ton of equipment, but using the right tools makes the process much smoother and more effective. Here’s a breakdown of the basic items you’ll need—and why each one is important.
1.) 5-Gallon Bucket
A large bucket is essential for holding your descaling solution while it circulates through the heater. A 5-gallon size is ideal because it can contain enough liquid to fully flush the system without overflow. You’ll place the pump and hoses in this bucket, so having one that’s sturdy and stable is key. If you don’t already have one at home, they’re inexpensive and easy to find at any hardware store. This bucket will also be used for the final rinse with clean water after descaling is complete.
2.) Submersible Pump
This small electric pump does all the heavy lifting during the descaling process. It circulates the solution through the cold water inlet and pushes it through the heater, allowing it to break down mineral deposits inside. Without a pump, the solution wouldn’t move through the system effectively, and descaling would be incomplete. Choose a pump with a decent flow rate (around 500–600 GPH works well) to ensure efficient cleaning. It’s a one-time investment that can be reused every year for maintenance.
3.) White Vinegar (or Commercial Descaling Solution)
White vinegar is a natural, affordable, and widely available option for descaling. It gently breaks down calcium and lime scale without damaging your pipes or components. You’ll need about 2–3 gallons for a full cleaning cycle. If the scale buildup is heavy or you’re looking for faster results, a commercial descaling product might be more effective. These are specially formulated to dissolve tough mineral deposits but should always be used according to the manufacturer’s instructions to avoid damage.
4.) Washing Machine Hoses
You’ll need two standard washing machine hoses to connect the submersible pump to the tankless water heater. One hose goes from the pump to the cold water inlet, and the other connects from the hot water outlet back to the bucket. These hoses allow the descaling solution to circulate in a closed loop, flushing out scale effectively. Make sure the hoses are clean and in good condition to prevent leaks during the process. They’re inexpensive and widely available at plumbing or hardware stores.
5.) Adjustable Wrench
An adjustable wrench is necessary for loosening and tightening the connections on your tankless water heater. You’ll use it to disconnect the hot and cold water lines and to attach the hoses from the pump. Choose a wrench that fits snugly but doesn’t strip the fittings. Having one on hand ensures you can complete the job without hassle or damage to the unit. It’s a simple yet vital tool that makes setup and cleanup much easier.
With these tools in your corner, you’ll be fully equipped to descale your tankless water heater the right way. They’re all easy to find, affordable, and reusable—making routine maintenance something you can handle without calling in a pro every time.
Step-by-Step Guide: How to Descale a Tankless Water Heater
Step 1: Turn Off the Heater and Shut Off Water Supply
Before starting, it’s crucial to turn off the power to your tankless water heater. If it’s an electric model, unplug it or flip the breaker. For gas units, simply turn off the gas valve. Once that’s done, close the cold water inlet and hot water outlet valves to isolate the heater from the rest of your plumbing. This ensures that no water will flow while you’re descaling the unit.
Step 2: Drain the Remaining Water
Even if you’ve turned off the water supply, there might still be some water left in the unit. Open the purge ports on your heater to let any remaining water drain out into a bucket or towel. This step prevents any old water from mixing with the new descaling solution.
Step 3: Set Up the Flushing System
Now it’s time to connect your submersible pump to the tankless water heater. Attach one of your washing machine hoses to the cold water inlet port and the other to the hot water outlet port. Place the pump into the bucket filled with the descaling solution. You want the pump to be fully submerged so it can circulate the solution effectively through the unit.
Step 4: Add the Descaling Solution
Pour about 2–3 gallons of white vinegar or a commercial descaling solution into the bucket. If you’re using vinegar, it’s a natural and effective choice that will gently break down the mineral deposits. For heavy buildup, a commercial product might be stronger and faster. Be sure to follow the manufacturer’s instructions if using a commercial descaler.
Step 5: Run the Pump and Circulate the Solution
Now that everything is connected, turn on the submersible pump to start circulating the descaling solution through the tankless water heater. Let it run for 45 minutes to 1 hour. The solution will break down the mineral buildup inside the unit. You may hear some bubbling or fizzing sounds, which is a sign that the solution is working to dissolve the scale.
Step 6: Rinse the System
After the descaling solution has circulated through the heater, it’s time to rinse out any remaining residue. Turn off the pump and dispose of the used solution. Refill the bucket with clean water and run the pump again for 10–15 minutes to flush out the remaining solution and any loosened mineral deposits.
Step 7: Reassemble and Power On the Heater
Once the system has been thoroughly rinsed, disconnect the hoses and reconnect the cold and hot water inlet/outlet lines. Open the water valves and restore power to your unit. Run hot water for a few minutes to ensure the system is flowing smoothly and that there are no leaks or strange sounds.
Need a hand with descaling? Let the experts at Baumbach Plumbing take care of it quickly and professionally. Call now or book online to keep your hot water running strong!
Tips to Prevent Future Mineral Buildup
Even after descaling your tankless water heater, it’s important to take a few extra steps to keep scale from coming back. These preventative measures will help maintain your system’s performance, reduce energy costs, and extend the life of your unit. Here’s what we recommend:
1.) Install a Water Softener
Hard water is the #1 reason scale builds up inside tankless water heaters. By installing a water softener, you eliminate the excess calcium and magnesium that causes scaling. A softener works by replacing these minerals with sodium, drastically reducing buildup in your pipes and heater. Over time, this not only improves performance but also protects your entire plumbing system. If your area is known for hard water, a softener is a must-have solution.
2.) Add a Sediment Filter
While a water softener targets minerals, a sediment filter protects your system from sand, rust, and other debris that flow in through your water supply. These tiny particles can clog the inner parts of your heater and cause unnecessary damage. So, what is a sediment filter exactly? It’s a device that traps sediment before it reaches your unit, acting like a shield for your plumbing. It’s a small upgrade that delivers long-term results. If your water comes from a well or older pipes, installing one is especially useful.
3.) Flush the System Regularly
Flushing your tankless water heater every 6 to 12 months helps prevent light mineral buildup from turning into a big problem. Even if your water is softened, small amounts of minerals can still slip through. A simple clean-water flush keeps things running smoothly and improves energy efficiency. It’s like giving your system a refresh before any major issues arise. Regular flushing can also help maintain your heater’s warranty.
4.) Schedule Annual Maintenance
Getting your tankless water heater professionally serviced once a year is one of the smartest moves you can make. A trained technician will inspect your unit, clean any hidden buildup, and catch potential issues early. Maintenance includes checking water pressure, examining internal parts, and testing system performance. At Baumbach Plumbing, we offer thorough, reliable checkups that keep your heater running like new. It’s quick, affordable, and gives you peace of mind all year long.
Frequently Asked Questions
1.) How often should I descale my tankless water heater?
It’s recommended to descale your tankless water heater once every 6 to 12 months, depending on your water quality. Homes with hard water may need more frequent cleanings to prevent scale buildup. If you have a water softener installed, you might get away with descaling just once a year. Regular maintenance keeps your unit efficient, extends its lifespan, and helps avoid costly repairs.
2.) Can I use vinegar instead of a commercial descaling solution?
Yes, white vinegar is a safe and effective option for descaling your tankless water heater. It’s affordable, non-toxic, and does a great job breaking down mineral deposits. However, if you have heavy scale buildup, a commercial descaling product may work faster and more thoroughly. Just be sure to follow the manufacturer’s instructions to avoid damaging your system.
3.) What happens if I don’t descale my tankless water heater?
Skipping descaling can lead to reduced efficiency, higher energy bills, and even permanent damage to your water heater. Over time, mineral deposits clog the heat exchanger and restrict water flow, making your system work harder than it should. If left untreated, this can shorten the lifespan of your heater and result in expensive repairs or replacements.
4.) Is descaling a tankless water heater something I can do myself?
Absolutely! Descaling your tankless water heater is a task that many homeowners can handle with just a few basic tools and a little patience. With a bucket, pump, vinegar (or descaling solution), hoses, and a wrench, you can perform the whole process in under two hours. If you’re unsure, though, calling a pro like Baumbach Plumbing ensures everything’s done safely and correctly.
5.) Does descaling improve water pressure and temperature?
Yes, it can! Scale buildup restricts water flow and interferes with heat transfer, which can cause low water pressure and inconsistent temperatures. After descaling, many homeowners notice an immediate improvement in hot water performance and overall system efficiency. It’s one of the quickest ways to get your heater running like new again.
Trusted Plumbing Solutions by Baumbach Plumbing & Remodeling
Whether you’re dealing with a leak, low water pressure, or planning a plumbing upgrade, Baumbach Plumbing & Remodeling is here to help. Our licensed professionals offer a full range of services, including drain cleaning, sewer line repair, pipe replacement, water heater installation and repair, and bathroom and kitchen plumbing remodeling. We use the latest tools and techniques to ensure efficient, long-lasting results.
Proudly serving Fairfax, McLean, Alexandria, and nearby areas, we’re committed to fast, reliable, and affordable plumbing solutions. Contact us today to schedule your service!
