Want your tankless water heater to run efficiently, deliver endless hot water, and last for years? Regular flushing is essential—especially in areas with hard water. Scale buildup can reduce efficiency, cause noise, trigger error codes, and even void your warranty. The good news: the right flush kit makes cleaning simple and safe. Whether you’re a first-time DIYer or an experienced homeowner, here’s your complete guide to the best tankless water heater flush kits, how to pick the right one, and what features to look for.
Quick Picks: Best Tankless Water Heater Flush Kits
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Best Overall:
My PlumbingStuff Tankless Water Heater Flushing Kit – Includes pump, hoses, bucket, and solution. User-friendly and compatible with all brands. -
Best Budget:
Kelaro Tankless Water Heater Flushing Kit – Simple, affordable, and gets the job done for less. -
Best Premium:
Eccotemp EZ-Flush System Descaler Kit – Commercial-grade pump and heavy-duty hoses for frequent or multi-unit maintenance.
Buyer’s Guide: How to Choose the Best Tankless Water Heater Flush Kit
Not all flush kits are created equal. Choosing the right set ensures a safe, thorough clean—without leaks or hassle. Here’s what matters most:
- Kit Components: Look for a complete kit: submersible utility pump, two hoses (4+ feet each), a large bucket, and optional descaling solution.
- Pump Strength: A pump rated at least 1/6 HP will circulate descaler through most tankless units effectively. Stronger pumps work faster, especially on bigger heaters or heavy scale.
- Hose Quality: Durable, kink-resistant hoses help prevent leaks and make setup easy. Standard garden hose threads ensure universal fit.
- Descaling Solution: Non-toxic, biodegradable solutions are safe for your heater and plumbing. Some kits include a bottle; otherwise, buy it separately.
- Bucket Size: A 3.5–5 gallon bucket holds enough liquid for a thorough flush and avoids messy overflows.
- Ease of Use: Look for kits with step-by-step instructions, color-coded parts, and quick connects for fast setup.
- Compatibility: Most kits fit all major brands (Rinnai, Navien, Noritz, Rheem, Takagi, and more).
How to Flush a Tankless Water Heater: The Basics
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Turn Off Power and Water
Unplug the heater (or turn off the breaker) and close both the hot and cold water shutoff valves. -
Connect the Hoses
Attach one hose to the cold water service port (to the pump), and the other to the hot water service port (to the bucket). -
Add Descaling Solution
Pour your solution (or white vinegar) into the bucket. -
Run the Pump
Plug in the pump and let it circulate for 45–60 minutes. The solution dissolves and removes mineral scale inside the heat exchanger. -
Flush with Fresh Water
Drain the solution, fill the bucket with clean water, and circulate for 5–10 more minutes to remove any residue. -
Restore Service
Disconnect hoses, close the ports, open the main valves, and restore power.
Always consult your heater’s manual for specific instructions, especially if you have special valves or models.
Top Reviews: Best Tankless Water Heater Flush Kits
My PlumbingStuff Tankless Water Heater Flushing Kit
Who it’s for: DIYers, homeowners, and anyone who wants an all-in-one kit for yearly descaling.
Key Benefits:
- Powerful submersible pump
- Flexible, kink-resistant hoses
- Big 3.5-gallon bucket for easy setup
- Includes non-toxic descaler
- Compatible with all brands and models
Pros:
- Everything included—no need to buy extra parts
- Reusable year after year
- Clear instructions for first-timers
Cons:
- Costs a bit more up front
- Requires storage space for the bucket
Final Verdict: This is the easiest, most foolproof kit for tankless flushes—highly recommended.
See it on Amazon
Kelaro Tankless Water Heater Flushing Kit
Who it’s for: Value-conscious owners who want a simple, effective flush for less.
Key Benefits:
- Good pump and hoses at a great price
- Quick and easy to use
- Fits all standard tankless units
- Step-by-step instructions included
- Reusable for years
Pros:
- Affordable
- Easy for first-time DIYers
- Gets the job done fast
Cons:
- Bucket not included
- No descaling solution in some versions
Final Verdict: A smart choice for regular maintenance—just add a bucket and you’re set.
Check price on Amazon
Eccotemp EZ-Flush System Descaler Kit
Who it’s for: Pros, landlords, or anyone with multiple heaters or tough buildup.
Key Benefits:
- Heavy-duty commercial pump for big or frequent jobs
- Extra-long, durable hoses
- Large, sturdy bucket included
- Compatible with all residential and commercial tankless units
- Designed for frequent use and longevity
Pros:
- Perfect for serious flushing or multiple properties
- Built to last
- Includes everything you need
Cons:
- Higher price
- May be overkill for single-heater homeowners
Final Verdict: The EZ-Flush is the pro’s choice for speed, power, and reliability.
See details on Amazon
Comparison Table
| Name | Key Features | Specs/Capacity | Price Link |
|---|---|---|---|
| My PlumbingStuff Kit | Pump, hoses, bucket, descaler | 3.5 gal bucket, 1/6 HP pump | View |
| Kelaro Kit | Pump, hoses, budget-friendly | No bucket, reusable, 1/10 HP pump | View |
| Eccotemp EZ-Flush | Heavy-duty, long hoses, full kit | Large bucket, high-flow pump | View |
FAQ: Tankless Water Heater Flush Kits
- How often should I flush my tankless water heater?
Once a year for most homes; every 6 months if you have hard water. - Can I use vinegar as a descaler?
Yes—plain white vinegar is safe and effective. Commercial descalers work faster on heavy buildup. - Will flushing void my warranty?
No—it’s required for most warranties. Regular flushing keeps your heater running longer. - Do I need a pro to flush my heater?
No—most homeowners can do it with a good kit and a little patience. - What happens if I don’t flush my heater?
Scale buildup reduces efficiency, causes noise, shortens lifespan, and can trigger expensive repairs.
Conclusion
Regular flushing is the single best way to keep your tankless water heater running strong for years. With the right flush kit, the job is safe, quick, and easy—no plumber needed. Whether you choose a full-featured kit or a budget pick, take an hour once a year and protect your investment. Clean heater, endless hot water, lower bills—what’s not to love?