INSTASHOWER ULTRA
66K BTU RV Tankless Water Heater with Mixing Tank
$899.99
Final Round Discount⚽
$220 off with code Victory220
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Victory220
More stable hot water from startup to shower.
InstaShower Ultra combines 66,000 BTU output, up to 3.9 GPM flow and a built-in mixing tank designed to reduce cold-water interruption. Segmented combustion targets steady outlet temperature while replacement-door options support common RV openings.
View all features ↓66,000 BTUHigh-output propane water heating
Up to 3.9 GPMFlow for showers and daily use
±1°FTemperature stability target
0.5 GPMLow-flow burner activation
Secure checkout
More options available at checkout
30-day returns
Free local shipping
2-year warranty
Not sure this is the right InstaShower?Compare all models
Fit and installation
- Door options
- 15×15 / 15×18 / 18×18 in
- Fuel
- LP propane
- Electrical supply
- 12V DC
- Water flow
- 0.5–3.9 GPM
- Altitude
- Up to 9,800 ft
Three door sizes cover common RV replacement openings. Full installation details are available in the guide.
What’s included
- ✓Water heaterInstaShower Ultra tankless unit
- ✓Access doorSelected color and door-size configuration
- ✓ControllerSmart wired controller
- ✓Safety valve150 PSI pressure relief valve
- ✓Product documentationInstallation hardware and user manual
Gas, water and electrical connection materials vary by RV.
Specifications
- Heat input
- 66,000 BTU
- Hot-water flow
- 0.5–3.9 GPM
- Temperature control
- ±1°F target
- Fuel
- LP propane
- Electrical supply
- 12V DC
- Maximum altitude
- 9,800 ft
Common questions
How do I choose the door size?
Choose the option that matches your current door dimensions. Available sizes update with the selected color.
What does the mixing tank do?
It buffers and blends water to reduce brief cold-water interruption when shower flow changes.
Does it need 120V power?
No. Controls and ignition use 12V DC; the burner uses LP propane.
Recommended for your RV setup
Pair the water-heater upgrade with climate equipment that matches how your RV is built. Confirm roof or duct requirements before ordering.
For non-ducted travel trailers and fifth wheels
InstaCool Ultra
+$1,299.99
$1,749.99
Add quiet rooftop cooling and heat-pump warmth for milder weather. Confirm a standard non-ducted roof opening, roof thickness and 115V power before ordering.
Check roof fit and options
For larger ducted RVs and cold-weather travel
InstaHeat 35K
+$799.99
$1,299.99
Add stronger propane heat through the RV duct system. Confirm cabinet space, central ductwork, 12V power and LP supply before ordering.
Check furnace fit and options
InstaShower Ultra
$220off
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$899.99
THE HIGHEST-FLOW INSTASHOWER
More hot water is useful. A smoother shower is what you notice.
InstaShower Ultra combines 66,000 BTU output, flow up to 3.9 GPM, a built-in mixing tank and a ±1°F temperature-control target. It is built for owners who want the strongest Fogatti tankless platform and fewer cold-water interruptions during normal RV shower use.
66,000 BTUHighest heat input
Up to 3.9 GPMHighest flow in the range
Built-in mixing tankSmoother restart
±1°FTemperature-control target
The mixing tank and burner control address the moments that usually make RV showers frustrating.
Ultra is not only a larger burner. Its water path and staged combustion are designed around temperature stability during real use.
BUILT-IN MIXING TANK
Restart the shower with less cold-water shock.
The internal pre-mix system blends water before it leaves the heater, reducing the brief cold interruption that can happen in an RV plumbing loop.
SEGMENTED COMBUSTION
The burner changes its flame pattern as water conditions change.
Lower flame staging helps reduce overheating in warm conditions, while the full burner supports colder inlet water and higher demand.
HIGHER FLOW
Up to 3.9 GPM provides more headroom for frequent shower use.
Actual flow depends on inlet-water temperature and desired temperature rise, but Ultra has the strongest flow platform in the range.
WEATHER-READY OPERATION
High-altitude and cold-weather systems support a wider travel range.
Correct propane, ventilation, 12V power and winterization remain essential for safe operation.
WHO SHOULD CHOOSE ULTRA?
Choose it when shower comfort and maximum flow justify the step up.
Ultra is intended for frequent users who value the mixing tank and higher output—not simply for anyone replacing a six-gallon heater.
A strong fit for frequent showers and higher demand
The 3.9 GPM platform adds more headroom for couples and families who use hot water often.
The mixing tank is the main comfort difference
It is designed to reduce cold-water interruption when the shower stops and restarts.
Choose 8 Pro or 8 Plus when the top output is unnecessary
The lower models can be a better value when household demand is lighter.
Choose the door from the actual opening, not the old tank label.
Measure the wall cutout and exterior trim coverage before choosing Gray or White and the door size.
INSTALLATION CHECK
Match the opening and confirm every utility connection.
The correct door covers the exterior opening, but plumbing, propane, 12V wiring and vent clearance still need to align.
- Minimum clear opening
- 13 × 13 in
- Door options
- 15×15 / 15×18 / 18×18 in
- Fuel
- LP propane
- Electrical supply
- 12V DC
- Maximum altitude
- 9,800 ft
White is available only in the configured 15 × 15-inch variant. Use the actual wall opening and exterior coverage—not tank capacity alone—to select the door.
Choose the heater around flow, stability and the existing opening.
Ultra is the strongest platform, while the lower models may deliver better value for lighter demand.
InstaShower Ultra
For the highest flow, tighter control and reduced cold-water interruption.
- Heat input
- 66K BTU
- Flow
- Up to 3.9 GPM
- Comfort
- Built-in mixing tank
InstaShower 8 Pro
For regular shower use, up to 3.1 GPM and a ±1°F stability target.
- Heat input
- 60K BTU
- Flow
- Up to 3.1 GPM
- Best for
- Frequent use
InstaShower 8 Plus
For continuous hot water and everyday midsize-RV shower demand.
- Heat input
- 55K BTU
- Flow
- Up to 2.9 GPM
- Best for
- Everyday replacement
See the mixing tank, installation and shower performance.
These videos show the parts and real use that explain why Ultra feels different from a basic tankless replacement.
▶FULL REPLACEMENT
See a tankless replacement from removal to startup
A complete installation walkthrough covering the opening, connections and first hot water.
▶TEARDOWN + TEST
See the mixing tank and burner before installation
An internal look at the parts designed to improve shower stability and service access.
▶OWNER EXPERIENCE
See why the mixing tank matters in normal use
A practical review focused on cold-water interruption and shower consistency.
Confirm that the highest-flow model fits both the RV and household.
Door fit, utility connections and incoming water conditions determine the final result.
How does the mixing tank help?
It blends water inside the heater to reduce the brief cold interruption that can occur when an RV shower stops and restarts.
Will I always get 3.9 GPM?
Maximum flow depends on inlet-water temperature, water pressure and the temperature rise requested.
How do I choose the door size?
Measure the actual wall cutout and exterior trim area. Do not choose from old tank capacity alone.
Does the heater need 120V power?
No. Ignition and controls use 12V DC, while heating uses LP propane.
Can I install it myself?
Experienced owners may complete the work, but propane, venting, water, electrical and weather-sealing connections must all be installed correctly.
Ready for the highest-flow InstaShower and a smoother restart?
Choose the color and door size above, then compare the installation manual with the existing opening and utilities.
This product is rated 5.0 of 5.0 stars.
It has received 25 reviews.
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