I'm planning several camping trips to mountain locations this summer, with many campgrounds sitting between 5,000 and 8,000 feet elevation. My travel trailer came equipped with a tankless on-demand water heater from the factory, and I'm concerned about how it will perform at these higher altitudes.
I've heard that propane appliances can have issues with combustion efficiency when there's less oxygen available in the thin mountain air. Specifically, I'm wondering about quantifiable performance losses - like what percentage of heating capacity I might lose per thousand feet of elevation gain. I'm also concerned about potential operational problems like flame failure or the unit shutting down completely at certain altitudes.
For context, most of my regular camping is done below 2,000 feet where the water heater works fine, but these upcoming mountain trips will be well above 4,500 feet elevation. Should I be worried about the tankless system's reliability at these altitudes, or am I overthinking this? Would I be better off considering a replacement with a traditional tank-style water heater if I plan to do more high-altitude camping in the future?
Tankless RV water heaters lose significant efficiency at high altitude - about 4% per 1,000 feet. Above 4,500 feet, expect reduced output and possible flame failure. Consider traditional tank heaters if you frequently camp in mountains.
Your concerns about tankless water heaters at high altitude are absolutely valid, and you're right that this is an under-discussed issue in the RV community. At elevations above 4500', tankless units do experience reduced performance due to decreased oxygen density, which affects combustion efficiency. Most RV tankless heaters will experience reduced performance at altitude - consult your specific manufacturer's specifications for exact derating factors, and yes, you'll likely see increased sooting, potential ignition issues, and inconsistent water temperatures without proper adjustment. Your current tanked water heater on the Rockwood is indeed much more forgiving at altitude since it doesn't rely on precise fuel-to-air ratios for continuous operation like tankless units do.
The primary culprit is oxygen depletion at higher elevations. Tankless water heaters require precise fuel-to-air mixing for optimal combustion, and the thinner air at 4500'+ disrupts this balance. The burner receives the same amount of propane but less oxygen, creating an overly rich mixture that burns inefficiently. This leads to incomplete combustion, resulting in carbon buildup, yellow flames instead of blue, and potential safety issues.
Another factor is the decreased atmospheric pressure affecting the unit's venting system. Many RV tankless heaters struggle to properly exhaust combustion gases at altitude, which can cause backdrafting and pilot light issues. The built-in safety sensors may also trigger more frequently, shutting down the unit when combustion isn't optimal.
Temperature differential problems become more pronounced at altitude too. The unit may cycle on and off more frequently as it struggles to maintain consistent output, leading to that annoying "cold sandwich" effect where hot water alternates with lukewarm water during showers.
WARNING: Working with propane appliances can be dangerous. Always shut off gas supply and allow complete cooling before any work. If you smell gas or are uncomfortable with any procedure, stop immediately and consult a professional.
Before heading to elevations above 4500', you'll want to have your tankless unit's orifices adjusted for high-altitude operation. This involves replacing the gas orifices with manufacturer-specified high-altitude parts to allow proper fuel flow, compensating for the reduced oxygen. Most manufacturers provide high-altitude conversion kits for elevations above 2000' and above 4500'. For popular RV units like Suburban and Girard tankless heaters, these kits typically cost $25-50 and include the correct orifices for your specific model and detailed instructions.
You'll also want to clean the burner assembly thoroughly before the conversion. Remove any existing carbon buildup using a soft brush and compressed air. Check the venting system for obstructions and ensure the intake and exhaust are clear. Document your current orifice sizes and settings before making changes, so you can reverse them when returning to lower elevations.
Gas pressure verification and adjustment should be performed by a certified technician, as this work may require special licensing and violate local safety codes if done incorrectly. Having the right tools and spare parts on hand will make the process much smoother than trying to find everything at a mountain hardware store.
WARNING: Ensure propane is completely shut off and unit is cool before beginning any work. Work in a well-ventilated area and have a gas detector available if possible.
Start by shutting off the propane supply and allowing the unit to cool completely. Remove the front cover and locate the gas valve assembly - this is where you'll find the orifices that need changing. Most RV tankless units have 2-4 orifices depending on the BTU rating. Replace the existing orifices with the manufacturer-specified high-altitude orifices included in your conversion kit for your specific model (verify correct part numbers with dealer). WARNING: Field-drilling or modifying orifices will void your warranty and create safety hazards.
Next, adjust the air shutter if your unit has one. Open it slightly more than the sea-level setting to allow additional air intake. This helps compensate for the thinner air density. Test the unit's operation, looking for steady blue flames rather than yellow or orange ones. If flames are still yellow, you may need to open the air shutter more or check for proper venting.
Check the gas pressure at the unit using your manometer against manufacturer specifications. Regulator adjustments should be performed by a certified technician as this work may require special licensing and violate local safety codes. Test the unit through several heating cycles, monitoring for consistent ignition, stable flames, and proper temperature output. Document these settings for future reference.
When returning to lower elevations, reverse the process by installing the original orifices and readjusting the air shutter and gas pressure to manufacturer specifications. Keep both sets of orifices clearly labeled and stored in your RV toolkit for future altitude changes.
If you're uncomfortable working with gas appliances or don't have experience with propane systems, definitely seek professional help. Many RV service centers in mountain areas are familiar with high-altitude conversions and can handle the adjustment for $75-150, which might be worth it for peace of mind and warranty considerations.
Call a professional if you encounter persistent pilot light issues, smell gas during operation, or see excessive yellow flames that won't correct with adjustments. These could indicate more serious problems like damaged gas valves, compromised venting, or internal component failures that require specialized diagnosis and repair.
Consider whether the hassle factor makes sense for your camping style. If you frequently move between different elevations, the constant need to adjust orifices might make your current tanked water heater the better choice. Many experienced high-altitude RVers stick with traditional tanked heaters specifically to avoid these complications, and there's no shame in prioritizing reliability over the perceived benefits of tankless technology. A properly calibrated manometer is essential for accurate pressure readings and should be checked against manufacturer specifications for your specific unit model.
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