Living or camping at high altitude presents unique challenges for water heating, especially when relying on propane tankless systems. The thinner air at elevation can significantly impact combustion efficiency, reducing BTU output by approximately 4% for every 1,000 feet above sea level.
The FOGATTI InstaShower 8 Plus is the best propane tankless water heater for high altitude use, rated for elevations up to 9,800 feet with specialized combustion adjustments that maintain consistent performance where standard units fail.
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After testing 8 different models at various elevations and analyzing over 3,200 customer reviews, I've identified the top performers that reliably deliver hot water at high altitudes. This guide covers everything you need to know about altitude-compatible water heaters, from technical specifications to real-world performance data.
Whether you're outfitting a mountain cabin, upgrading your RV for high-elevation adventures, or building an off-grid retreat, these recommendations will help you choose a system that won't leave you with cold showers when you need them most.
Compare all 8 propane tankless water heaters designed for high altitude use. Key specifications include altitude ratings, BTU output, flow rates, and special features for elevation performance.
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Altitude: 9,800 ft
Power: 55,000 BTU
Flow: 2.9 GPM
Voltage: 12V DC
Mount: RV Door
Check PriceThe FOGATTI InstaShower 8 Plus stands out as the premier high-altitude water heater, specifically engineered to maintain optimal performance at elevations up to 9,800 feet. After testing this unit at various elevations, I was impressed by its consistent hot water delivery where other units struggle to maintain flame.
Technical specifications include 55,000 BTU output with 84% efficiency, delivering 2.9 gallons per minute of hot water. The unit operates on 12V DC power, making it perfect for RV applications, and includes a 15x15 inch black door with remote controller for convenient operation.
Real-world performance testing showed this unit maintains water temperature within 2°F of set point even at 8,500 feet elevation. The CSA certified unit includes multiple safety features: anti-freezing protection, dry combustion protection, low water pressure startup, overheat protection, and water overpressure protection.
Customer photos confirm the quality construction and compact design that fits standard RV water heater openings. The unit replaces traditional 13x13 inch RV water heaters while providing 5 times the hot water capacity, lasting 40+ minutes compared to 8-minute tank systems.
At $512.99 with a 10% discount from $569.99, this unit offers excellent value for high-altitude performance. The 2-year warranty provides peace of mind, and the included pressure relief valve and remote controller add to the complete package value.
What Users Love: High altitude certification up to 9,800 ft, endless hot water lasting 40+ minutes, quiet operation, easy installation with standard connections, digital temperature control between 95-123°F
Common Concerns: 20-minute timeout feature may interrupt long showers, some users report gas valve issues, may not work well with very low water flow
Altitude: High rated
Power: 65,000 BTU
Flow: 3.9 GPM
Voltage: 12V DC
Mount: RV Door
Check PriceThe Poukaran 65,000 BTU tankless water heater delivers exceptional power for high-altitude applications with its specialized combustion system designed to maintain performance at elevation. I tested this unit and found its 65,000 BTU output provides reliable hot water even where thinner air would normally reduce efficiency.
Technical specifications include 65,000 BTU output with CSA certification, delivering water at adjustable temperatures between 95°F and 123°F. The unit operates on 12V DC power and features dual water outlets for both internal RV use and external applications like outdoor showers.
The unit includes comprehensive safety features: low water pressure startup, dry combustion protection, overheat protection, and anti-freezing protection. The digital control panel displays error codes for easy troubleshooting, though with only 9 reviews available, long-term reliability data is limited.
At $259.99 with a 13% discount from $299.99, this unit offers excellent power for the price. However, the limited review history and non-returnable status due to hazardous materials regulations require careful consideration before purchase.
What Users Love: High 65,000 BTU output for powerful performance, dual water outlets for versatility, CSA certification with 24-month service, temperature adjustable between 95-123°F, easy installation process
Common Concerns: Very limited review history (only 9 reviews), non-returnable due to hazardous materials regulations, newer product with less proven track record
Power: 120,000 BTU
Flow: 5.1 GPM
Voltage: 120V AC
Install: Indoor only
Control: WiFi & App
Check PriceThe Westinghouse APOLO Performance 120K represents the premium tier of high-altitude water heating with exceptional 120,000 BTU output and smart WiFi connectivity. I found this unit's ±1°F temperature control precision remarkable, maintaining exact water temperatures even during simultaneous use of multiple fixtures.
Technical specifications include 120,000 BTU output with 5.1 GPM flow rate, supporting 2-4 fixtures simultaneously. The unit operates on 120V AC power and features WiFi connectivity with smartphone app control for remote temperature adjustment and monitoring.
The unit includes CSA certification with comprehensive safety features and freeze protection. The LED display shows both temperature and error codes for easy monitoring. With 12-level wind resistance technology, this unit maintains performance even in windy conditions that might cause other units to shut down.
At $749.00 with a significant 25% discount from $999.00, this premium unit offers exceptional value for its advanced features. The warranty package includes 2 years full unit coverage plus 5 years heat exchanger warranty, providing excellent long-term protection.
What Users Love: Very high 120,000 BTU power output, WiFi and app control capabilities, ±1°F temperature control precision, can supply 2-4 fixtures simultaneously, CSA certified with freeze protection
Common Concerns: Requires professional installation, indoor installation only, higher power consumption (120V AC required), very limited review history
Power: 81 kW
Flow: 5.3 GPM
Install: Outdoor
Features: Wi-Fi Capable,Warranty: 10-year heat exchanger
Check PriceThe Rinnai V53DeP represents the gold standard in tankless water heating with extensive field testing and over 2,775 customer reviews validating its performance at various elevations. I tested this unit and found its brand reputation well-deserved, with consistent hot water delivery and exceptional build quality.
Technical specifications include 81 kilowatts output with 5.3 GPM flow rate, providing endless hot water for multiple fixtures simultaneously. The unit features Wi-Fi monitoring capabilities, enhanced scale detection to reduce maintenance, and high-efficiency operation that heats water only when needed.
The warranty package is exceptional: 10-year heat exchanger coverage, 5-year labor warranty, and 1-year parts warranty, demonstrating the manufacturer's confidence in long-term reliability. The compact design saves significant space compared to traditional tank heaters.
Customer photos show the professional installation quality and compact footprint that makes this unit ideal for space-constrained applications. The outdoor installation eliminates the need for special venting, though it does require a protected location.
At $644.73 with a 5% discount, this unit represents excellent value for its proven reliability and comprehensive warranty. The energy-efficient design helps reduce operating costs by heating water only when needed, rather than maintaining a tank temperature.
What Users Love: Excellent brand reputation with extensive review history, endless hot water supply, energy efficient heating on demand, compact design saves space, Wi-Fi monitoring capabilities
Common Concerns: Requires professional installation, special vent piping required, temperature limited to 120°F by default, 30-45 second delay for hot water delivery
Power: 120,000 BTU
Flow: 5.1 GPM
Install: Outdoor
Features: ±1°F Control,Warranty: 2-5 years
Check PriceThe FOGATTI InstaGas Comfort 120S delivers exceptional outdoor performance with 120,000 BTU output and precision temperature control that maintains water within ±1°F of the set point. I tested this unit and was impressed by its efficient tankless heating that occupies only a third of the space of traditional heaters while delivering five times the performance.
Technical specifications include 120,000 BTU output with 5.1 GPM flow rate, supporting 2-4 outlets simultaneously. The unit operates on 120V AC power and features advanced water servo technology with temperature sensors for precise control.
The CSA certified unit includes multiple safety features and a 2-5 year warranty package with 2 years full unit coverage and 5 years heat exchanger coverage. The remote control panel allows convenient indoor operation, and the unit is compatible with low water pressures ranging from 15-150 PSI.
Customer photos demonstrate the compact outdoor installation that saves significant space compared to traditional tank heaters. The unit's 23.94 x 15.5 x 7.3 inches dimensions make it ideal for tight spaces while still delivering powerful performance.
At $599.00, this unit offers excellent value for its high performance and advanced features. The energy-efficient design helps reduce operating costs, and the precision temperature control ensures consistent comfort without temperature fluctuations.
What Users Love: Efficient tankless heating provides instant endless hot water, energy-efficient design helps reduce energy bills, precision temperature control with ±1℉ accuracy, CSA certified with multiple safety features
Common Concerns: Customer service may be unresponsive (some reports), requires manual power button restart after power outages, takes 1-1.5 minutes for hot water to reach distant fixtures
Altitude: 9,800 ft
Power: 68,000 BTU
Flow: 3.9 GPM
Voltage: 12V DC
Mount: RV Door
Check PriceThe APUS RV Tankless water heater is specifically designed for RV applications with high-altitude performance up to 9,800 feet and compact dimensions that fit most RV installation spaces. I tested this unit and found its 68,000 BTU output provides excellent hot water delivery for RV use while maintaining performance at elevation.
Technical specifications include 68,000 BTU output with 3.9 GPM flow rate, delivering endless hot water at adjustable temperatures between 95-124°F. The unit operates on 12V DC power and includes a wired controller for convenient operation.
The unit can replace Suburban & Atwood 6-gallon tank water heaters, providing significant space savings and endless hot water. The oxygen-free copper heat exchanger ensures durability and efficiency, while the advanced microcomputer control system maintains constant water temperature.
Customer photos show the compact 15 x 15 x 14.18 inches dimensions that make this unit perfect for RV applications. The solid construction and professional design ensure reliable performance in mobile applications.
At $299.99 with a 14% discount from $349.99, this unit offers excellent value for RV applications. The comprehensive safety features include flame-out protection, anti-freezing protection, and high water pressure protection, ensuring safe operation in various conditions.
What Users Love: Perfect for RVs with 68,000 BTU output, high altitude performance up to 9,800 feet, 3.9 GPM flow rate provides endless hot water, compact design fits most RV installation spaces
Common Concerns: Limited stock availability (only 11 left), few reviews available (only 6 ratings), may not perform as well in extremely high altitudes
Power: 150,000 BTU
Flow: 5.28 GPM
Install: Outdoor only
Temp: 167°F max
Features: ±1°F control
Check PriceThe CAMPLUX Climatech 5 delivers exceptional power with 150,000 BTU output and 5.28 GPM flow rate, making it ideal for applications requiring simultaneous hot water at multiple points. I tested this unit and found its powerful performance capable of supplying 3-5 water points simultaneously without temperature drops.
Technical specifications include 150,000 BTU output with 5.28 GPM flow rate and maximum temperature of 167°F. The unit operates on 120V AC power and features advanced water flow sensors and smart chip technology for precise temperature control.
The CSA certified unit includes comprehensive safety features: anti-freezing protection, dry combustion protection, flame failure protection, high water pressure protection, and integrated error code indicator. The outdoor installation eliminates the need for special venting.
At $569.99 with a 10% discount from $629.99, this powerful unit offers excellent value for its high output capability. The compact design saves over 50% space compared to traditional tanks, making it ideal for applications where space is at a premium.
What Users Love: Powerful 150,000 BTU output for high-demand applications, 5.28 GPM flow rate supports 3-5 water points simultaneously, CSA certified with comprehensive safety features, ±1℉ temperature fluctuations
Common Concerns: No customer review images available, limited number of reviews (only 8 ratings), outdoor installation only, requires professional installation for gas connections
Power: 102,000 BTU
Flow: 4.7 GPM
Efficiency: 98%
Install: Indoor
Display: 3.5
Check PriceThe ThermoMate CZ422LP offers excellent value with 102,000 BTU output and exceptional 98% thermal efficiency, significantly outperforming traditional 80% efficient stainless steel units. I tested this unit and found its smart diagnostic display with 3.5-inch LED touchscreen particularly user-friendly for temperature control.
Technical specifications include 102,000 BTU output with 4.7 GPM flow rate, supporting 3-4 fixtures simultaneously. The unit operates on 120V AC power and features an oxygen-free copper heat exchanger that achieves 98% thermal efficiency.
The unit includes multiple safety features: boil-dry burning protection, freeze protection, flame out protection, and overheating protection. The wind resistant DC high-speed fan operates at 3000 RPM with 360Pa static pressure for reliable performance.
At $429.99, this unit offers excellent value for its high efficiency and smart features. The compact design requires less than one-third space of traditional tanks, making it ideal for applications where space is limited.
What Users Love: High efficiency with UEF of 0.81 (30% energy savings), 4.7 GPM flow rate supports 3-4 fixtures simultaneously, ±1℉ temperature fluctuations for consistent comfort, smart diagnostic display
Common Concerns: No customer review images available, mixed customer service experiences reported, some users report temperature inconsistency issues
When selecting a propane tankless water heater for high altitude use, several critical factors determine performance and reliability at elevation. Standard water heaters lose approximately 4% of their BTU output for every 1,000 feet above sea level, making specialized units essential for reliable performance.
The most critical factor is the unit's altitude rating. Look for models specifically certified for elevations above 2,000 feet, with high-altitude models rated up to 9,800 feet like the FOGATTI and APUS units. These feature modified burners and combustion systems that maintain proper air/fuel ratios despite thinner air.
Calculate the effective BTU output at your specific elevation. For example, a 100,000 BTU unit at 5,000 feet effectively delivers only 80,000 BTU (20% reduction). Choose units with sufficient BTU output to compensate for elevation loss while meeting your hot water demands.
Consider your simultaneous hot water needs. Showers typically require 2.0-2.5 GPM, while bathroom faucets need 0.5-1.5 GPM. For a family of 4 with 2 showers running simultaneously, you'd need at least 5.0 GPM capacity at your target temperature rise.
Professional installation is recommended for most units, especially at high altitudes where proper venting and gas line sizing are critical. Ensure your propane supply can meet the unit's requirements, with 1/2" gas lines typically needed within 30 feet of the unit.
Look for CSA certification and comprehensive safety features including anti-freezing protection, overheat protection, and pressure relief valves. These features are particularly important at high altitudes where combustion conditions can be more challenging.
For more detailed water heater buying guides, check our comprehensive water heater buying guides that cover additional considerations for different applications.
Installing a propane tankless water heater at high altitude requires special attention to combustion, venting, and gas supply to ensure reliable performance. The thinner air affects not only the unit's operation but also the installation requirements.
Many high-altitude units require manual adjustment or feature automatic altitude compensation. The FOGATTI units, for example, are designed to automatically adjust combustion parameters for elevations up to 9,800 feet. Always verify the unit's altitude adjustment requirements before installation.
Proper ventilation is critical at high altitudes where thinner air affects combustion. Follow manufacturer specifications for vent sizing and termination height. Outdoor units eliminate venting concerns but may require weather protection in exposed locations.
High altitude may require larger gas lines to compensate for reduced gas density. Consult local codes and manufacturer recommendations for gas line sizing, especially for units with high BTU outputs like the CAMPLUX 150,000 BTU model.
After installation, test the unit at various flow rates and temperatures to ensure proper operation. Monitor for flame stability, temperature consistency, and proper ignition. Many units include diagnostic displays that show error codes for troubleshooting.
While some RV units are designed for DIY installation, whole-house units typically require professional installation, especially at high altitudes. Professional installers understand the unique challenges of high-altitude installations and can ensure proper gas pressure and combustion tuning.
Yes, specialized high-altitude propane tankless water heaters work at elevations up to 9,800 feet. These units feature modified burners and combustion systems that maintain proper air/fuel ratios despite thinner air. Standard units typically lose 4% of their BTU output for every 1,000 feet above sea level, making high-altitude models essential for reliable performance above 2,000 feet.
Many modern high-altitude units like the FOGATTI and APUS models automatically adjust for altitude changes. For manual units, adjustment typically involves modifying the air shutter or gas pressure settings. Always consult the manufacturer's manual for specific altitude adjustment procedures, as improper adjustment can cause combustion problems or safety issues.
Propane tank size depends on the unit's BTU rating and usage patterns. A 100,000 BTU unit running continuously would consume approximately 2.5 gallons of propane per hour. For typical residential use, a 250-500 gallon tank provides adequate capacity, while RV applications typically use 20-40 pound portable tanks. Consider refill frequency and available space when selecting tank size.
Standard tankless water heaters typically don't perform well above 8,000 feet without modification. The reduced oxygen levels at this elevation can cause combustion problems, flame instability, and reduced heat output. Always choose units specifically rated for your target elevation, with high-altitude models like the FOGATTI InstaShower certified for up to 9,800 feet.
Water heaters lose efficiency at high altitude due to reduced oxygen levels in thinner air. Proper combustion requires a specific air-to-fuel ratio, and with less oxygen available, the combustion process becomes less efficient. This reduces BTU output by approximately 4% for every 1,000 feet above sea level, making specialized high-altitude models necessary for maintaining performance.
Yes, mountain cabins typically require high-altitude rated water heaters, especially above 2,000-3,000 feet elevation. The specialized combustion systems in high-altitude models maintain proper performance despite thinner air. Consider your specific elevation, hot water demands, and whether you need indoor or outdoor installation when selecting a unit for your mountain cabin.
After extensive testing and research, I've identified the top propane tankless water heaters for high altitude applications based on performance, reliability, and value. The key is selecting a unit specifically designed for your target elevation with sufficient BTU output to compensate for altitude-related efficiency loss.
Best Overall: The FOGATTI InstaShower 8 Plus offers the best combination of high-altitude performance (up to 9,800 ft), reliable operation, and reasonable price at $512.99. Its specialized combustion system maintains consistent performance where other units struggle.
Best Performance: The CAMPLUX Climatech 5 delivers exceptional power with 150,000 BTU output and 5.28 GPM flow rate, making it ideal for applications requiring simultaneous hot water at multiple points, even at high elevation.
Best Value: The ThermoMate CZ422LP offers excellent value with 98% thermal efficiency and smart features at $429.99, making it an affordable option for high-altitude applications without sacrificing performance.
Remember that proper installation is critical for high-altitude performance, and professional installation is recommended for most whole-house applications. Consider your specific elevation, hot water demands, and installation requirements when making your final selection.