Buying Guide
4 Best RV Tankless Water Heater With Mixing Tank in 2026: A Practical RV Guide
Best RV tankless water heaters with a built-in mixing tank compared on buffer design, flow claims, certifications and door fit.
By Hardcastle's RV Editors
10 min read4 products evaluated
A built-in mixing tank buffers the temperature swings that make cheap tankless showers go hot then cold. This shortlist compares four 65,000 BTU-class propane heaters that describe a mixing tank or chamber in their own listings.
Each heater was read for how it describes the buffer, claimed flow and altitude rating, certifications and door fit. GPM claims depend on temperature rise and are reported as listing claims.
Hardcastle’s RV field notes
The Rig Fit Check
A quick way to connect the shortlist to the space, workload and ownership details that matter after the box arrives.
- Start with the job
- CAMPLUX RV Tankless Water Heater leads this shortlist for Boondockers. Use that fit as a reference point, then compare the alternatives against your own space and workload.
- Specs that separate the picks
- The first details to compare are Built-in mixing tank, Thermostatic mixing chamber, 16.9 oz mixing tank. Confirm the exact model and included components before ordering.
- Trade-off to plan for
- Needs 12V power
The Practical Shortlist
A road-tested-thinking look at 4 options, organized around the job each one suits best.
Best Low-Flow Startup
CAMPLUX RV Tankless Water Heater
Boondockers
Our take Check price for CAMPLUX RV Tankless Water Heater (opens in a new tab)
Best Thermostatic Chamber
Ranein RV Tankless Water Heater
Data-minded buyers
Our take Check price for Ranein RV Tankless Water Heater (opens in a new tab)
Best Budget Mixing Tank
AVOYTE RV Tankless Water Heater
Budget mixing tank buyers
Our take Check price for AVOYTE RV Tankless Water Heater (opens in a new tab)
Best Premium Altitude Unit
FOGATTI InstaShower 9 Pro RV Tankless Water Heater
Precision-temperature buyers
Our take Check price for FOGATTI InstaShower 9 Pro RV Tankless Water Heater (opens in a new tab)
| Pick | Best for | Key spec | Price |
|---|---|---|---|
| Boondockers | Built-in mixing tank | Check price for CAMPLUX RV Tankless Water Heater (opens in a new tab) |
| Data-minded buyers | Thermostatic mixing chamber | Check price for Ranein RV Tankless Water Heater (opens in a new tab) |
| Budget mixing tank buyers | 16.9 oz mixing tank | Check price for AVOYTE RV Tankless Water Heater (opens in a new tab) |
| Precision-temperature buyers | 66,000 BTU, 3.6 GPM | Check price for FOGATTI InstaShower 9 Pro RV Tankless Water Heater (opens in a new tab) |
Why Each Pick Made the Cut
Best Low-Flow Startup1 of 4
CAMPLUX RV Tankless Water Heater on Amazon (opens in a new tab)
CAMPLUX RV Tankless Water Heater is the better fit when boondockers.
Best for
- Boondockers
Why it made the shortlist
The CAMPLUX RV Tankless Water Heater is a 65,000 BTU propane unit with a built-in mixing tank, a multi-stage burner and CSA and NSF certification. It lists ignition at ultra-low 0.5 GPM and up to 3.9 GPM output for simultaneous use.
It is the pick for boondocking, since the 0.5 GPM startup saves propane and fresh water. It performs at 9,800 feet per the listing.
Best for boondockers who want low-flow ignition and a certified buffer. It also suits families.
Key dimensions & specs
- Built-in mixing tank
- 0.5 GPM startup
- CSA and NSF certified
Pros
- Ultra-low 0.5 GPM startup
- CSA and NSF certified
- Multi-stage burner
- Rated for 9,800 ft
Cons
- Needs 12V power
Best Thermostatic Chamber2 of 4
Ranein RV Tankless Water Heater on Amazon (opens in a new tab)
Choose Ranein RV Tankless Water Heater for remote shows gas, voltage and flow.
Best for
- Data-minded buyers
Why it made the shortlist
The Ranein RV Tankless Water Heater (RA65LH) is a CSA 65,000 BTU unit claimed at 3.9 GPM with a thermostatic mixing chamber that balances heat output. It fits a 12.8 by 12.8 inch opening and replaces most Suburban and Atwood 6, 10 and 12 gallon heaters.
A multi-function remote shows gas use, voltage, flow and anti-freeze status, which no other pick lists. Compared with the AVOYTE, it adds that remote.
A great pick for owners who want data from a remote. It also suits standard cutouts.
Key dimensions & specs
- Thermostatic mixing chamber
- 12.8 inch opening
- Multi-function remote
Pros
- Remote shows gas, voltage and flow
- Thermostatic chamber steadies temperature
- Fits 12.8 inch opening
- CSA certified
Cons
- Exterior door sold separately
Best Budget Mixing Tank3 of 4
AVOYTE RV Tankless Water Heater on Amazon (opens in a new tab)
AVOYTE RV Tankless Water Heater makes the shortlist because stated 16.9 oz mixing tank.
Best for
- Budget mixing tank buyers
Why it made the shortlist
The AVOYTE RV Tankless Water Heater has a 16.9 oz built-in mixing tank and a 65,000 BTU burner claimed at up to 3.9 GPM. It is CSA certified with seven safety protections and rated for 9,800 feet.
It costs about $280, well below the CAMPLUX and Ranein, and lists anti-freeze protection. The mixing tank buffers overcooled or overheated flow.
Best for budget buyers who want a real mixing tank. It also suits cross-country travelers.
Key dimensions & specs
- 16.9 oz mixing tank
- 65,000 BTU, 12V
- 7 safety protections
Pros
- Stated 16.9 oz mixing tank
- CSA certified
- Rated for 9,800 ft
Cons
- Less brand history
- Needs 12V power
Best Premium Altitude Unit4 of 4
FOGATTI InstaShower 9 Pro RV Tankless Water Heater on Amazon (opens in a new tab)
The strongest case for FOGATTI InstaShower 9 Pro RV Tankless Water Heater is plus or minus 1 F temperature control.
Best for
- Precision-temperature buyers
Why it made the shortlist
The FOGATTI InstaShower 9 Pro is a third-generation tankless heater with a built-in mixing tank, 66,000 BTU and up to 3.6 GPM. The listing says it runs at altitudes up to 9,800 feet and holds temperature within plus or minus 1 F.
It includes a 150 PSI pressure relief valve and a 13 by 13 inch opening that can replace Suburban and Atwood heaters.
Best for buyers who want tight temperature control. It also suits high-altitude travelers.
Key dimensions & specs
- 66,000 BTU, 3.6 GPM
- Plus or minus 1 F control
- 150 PSI relief valve
Pros
- Plus or minus 1 F temperature control
- Relief valve included
- Rated for 9,800 ft
- 13 by 13 inch opening
Cons
- Needs 12V power
How We Built This Shortlist
Each pick was assessed across 4 criteria weighted for real-world use.
- Mixing tank
- Only listings naming a mixing tank or chamber were included.
- Flow claims
- GPM claims were treated as listing claims.
- Certifications
- CSA and NSF wording was read exactly.
- Fit
- Opening sizes were compared.
What Matters Before You Choose an RV Tankless Water Heater With Mixing Tank
Key buying criteria so you get the right fit the first time.
Why a mixing tank
A small buffer smooths temperature swings when flow or inlet temperature changes. It matters for comfortable showers. Look for a stated tank volume.
Mixing tank vs chamber
A physical 16.9 oz tank and a thermostatic chamber work differently. It matters for how steady output stays. Read each description.
Low-flow startup
A low minimum flow saves propane and water. It matters when boondocking. Look for 0.5 GPM.
Certifications
CSA covers appliance safety, and NSF covers water-contact materials. It matters for safe use. Read which is listed.
Opening size
12.8 or 13 inch openings suit retrofits. It matters for fit. Measure first.
Match an RV Tankless Water Heater With Mixing Tank to Your RV
By what you want most
| Your situation | Recommended pick | Why |
|---|---|---|
| Low-flow boondocking | CAMPLUX Elite10 | 0.5 GPM startup |
| Remote data | Ranein RA65LH | Multi-function remote |
| Lowest cost | AVOYTE 65,000 | 16.9 oz mixing tank at about $280 |
| Tight temperature control | FOGATTI InstaShower 9 Pro | Plus or minus 1 F |
Scroll sideways to see every column.
By Budget
| Budget | Recommended pick |
|---|---|
| $270 to $450 | AVOYTE 65,000 or Ranein RA65LH |
| $450 to $700 | CAMPLUX Elite10 or FOGATTI InstaShower 9 Pro |
Mixing tank vs thermostatic chamber
- Mixing tank
- The CAMPLUX Elite10, AVOYTE 65,000 and FOGATTI InstaShower 9 Pro list a built-in tank that buffers flow.
- Thermostatic chamber
- The Ranein RA65LH uses a chamber that balances heat output dynamically.
Most buyers should choose the AVOYTE 65,000 for a low-cost mixing tank.
By altitude and climate
| Condition | Recommended pick |
|---|---|
| High altitude | FOGATTI InstaShower 9 Pro |
| Cold nights | AVOYTE 65,000 |
| Boondocking | CAMPLUX Elite10 |
| Standard cutouts | Ranein RA65LH |
For Showers With Kids Specifically
- Look for
- steady temperature and safeties
- In this comparison
- The AVOYTE 65,000 lists seven protections and the FOGATTI InstaShower 9 Pro holds plus or minus 1 F.
When to Spend More
- Spend more if
- Spend more if temperature steadiness matters: the FOGATTI InstaShower 9 Pro and Ranein RA65LH cost more.
- Save if
- Save if you want the buffer at a low cost: the AVOYTE 65,000 is about $280.
Before You Bring One Home
Do I need a mixing tank?
It helps smooth temperature swings, especially at low flow. Without it, some tankless units fluctuate.
What mistake do people make?
Assuming all tankless heaters buffer temperature. Check for a mixing tank or chamber.
Is the Ranein RA65LH worth it over AVOYTE 65,000?
If you want a data remote, yes. Otherwise the AVOYTE 65,000 costs less.
How do I install it?
Shut off propane and power, remove the old unit, connect the water and gas lines and test every joint for leaks. Follow the manufacturer's instructions, and consider a professional for gas work.
How do I winterize it?
Use the freeze protection if the unit is powered and has propane available. Drain the unit and water lines before storing in freezing weather.
Bottom Line
Best overall: CAMPLUX RV Tankless Water Heater — best low-flow startup pick in this roundup. See the full verdicts above for every pick, with pros, cons and who each one suits.
Browse all rv tankless water heater with mixing tank on Amazon — Prime-eligible options with current pricing.