Tankless water heater sizing Last reviewed June 30, 2026
RV Tankless Water Heater Sizing Guide
By the WhatSize editorial team 4 min read Standards-reviewed
RV tankless units are typically 1–2.5 GPM at 42,000–66,000 BTU propane. Top brands: Fogatti (42k–66k BTU), Camplux (68k–170k BTU), Girard. Camplux whole-RV unit: 6.86 GPM at 170k BTU.
Why RV tankless is a unique category
RV tankless water heaters are a specialized segment that runs exclusively on propane and operates at much lower flow rates than residential units. Per ENERGY STAR fixture rates, RV low-flow fixtures run 1.0–1.5 GPM, so RV tankless units are sized accordingly: 1.0–2.5 GPM at 42,000–66,000 BTU for single-fixture, up to 6.86 GPM at 170,000 BTU for whole-RV use.
Top RV brands verified June 2026 (manufacturer spec analysis):
- Fogatti (RV-only line, $300–$700): InstaShower 7 (42k BTU), InstaShower 8 Plus (55k), 8 Pro (60k), 9 Pro (66k), Ultra (66k). RV-typical.
- Camplux (RV + residential, $300–$700): CA264 (2.64 GPM / 68k BTU / $299), CA318 (3.18 / 82k / $399), CA422 (4.22 / 102k / $499), CA528 (5.28 / 132k / $499), WA686 (6.86 / 170k / $699). Whole-RV top pick.
- Girard / Truma (premium Class A, $800–$1,500): Girard 2GWHAM (~2.5 GPM, 42k BTU, 0.34 gal/hr propane); Truma AquaGo Comfort (~1.5 GPM continuous, 50k BTU).
Propane math (verified): 1 gallon propane = 91,500 BTU gross / 73,000 BTU at 80% efficiency. A 5.28 GPM Camplux at 170k BTU and 80% efficiency: 170,000 × 73,000 = ~2.33 gal/hr propane at full fire. Standard 20 lb BBQ tank (4.7 gallons / 344,000 BTU usable) runs a 100k BTU unit for ~3.4 hours of continuous max-fire.
RV-specific constraints: 12V DC for controls (battery draw when boondocking); 1/2" propane line minimum; no power = no hot water on modern models; winterization critical below 32°F.
Top picks for this size
These Amazon-available picks meet the calculated spec. For region-specific or licensed contractor-installed options, consult a local professional. See our Disclaimers.
When RV tankless makes sense
- Travel trailer / Class B van: Fogatti InstaShower 7 (42k BTU, ~$300) — entry pick. Saves 12–18 lbs and 8–14 cu ft vs 6-gal tank.
- Class A motorhome: Camplux WA686 (6.86 GPM, 170k BTU, $699) — budget whole-RV; Truma/Girard for premium.
- Boondocking / off-grid: Propane tankless uses less propane than frequent tank reheating; runs out faster on demand but holds 12V idle better.
- Avoid: Standard residential fixtures (3 GPM+) won't work — must use RV-specific low-flow fixtures.
Frequently asked questions
What size tankless for an RV?
RV tankless units are typically 1–2.5 GPM at 42,000–66,000 BTU propane (Fogatti InstaShower line), or 2.6–6.86 GPM at 68k–170k BTU for small whole-RV use (Camplux line). Top brands: Fogatti (RV-only), Camplux (RV + residential), Girard, Truma.
How much propane does an RV tankless use?
Propane consumption math: 1 gallon propane = 91,500 BTU gross, ~73,000 BTU delivered at 80% efficiency. A 5.28 GPM Camplux running at 170,000 BTU and 80% efficiency consumes 170,000 × 73,000 = ~2.33 gal/hr propane at max fire. A 20 lb BBQ tank (4.7 gallons) provides ~3.4 hours of continuous max-fire use — most RV uses are intermittent so real-world consumption is much lower.
Can I install RV tankless myself?
Yes, RV tankless installation is straightforward for DIY-savvy RVers. Mount the unit, connect 1/2" propane line, connect 3/8" water lines, add 12V electrical for ignition. Plan 2–4 hours. Critical: vent exhaust gases outside per manufacturer instructions, and ensure the unit is in a sealed enclosure to prevent exhaust infiltration into the living space.
What's the best RV tankless water heater?
Top brands: Fogatti (popular for travel trailers, $300–$700), Camplux (budget-friendly, $300–$700), Girard (premium for Class A, $800–$1,500), Truma (German engineering, premium $1,000+). For Class A motorhomes, Girard and Truma are premium choices. For travel trailers, Fogatti and Camplux offer best value.
You might also need
More tankless water heater sizing guides
- What Size Tankless Water Heater for a Family of 4?
- What Size Tankless Water Heater for a Family of 2—?
- What Size Tankless Water Heater for a Family of 5—?
- Electric Tankless Water Heater Sizing Guide
- Gas Tankless Water Heater Sizing Guide
- Electric vs Gas Tankless Water Heater: Which Size & Type?
- Heat Pump vs Tankless Water Heater: Size & Efficiency
- Tankless Water Heater Sizing for Cold Climates
- Propane Tankless Water Heater Sizing Guide
- Tankless Water Heater Installation Cost Guide
Still choosing between sizes? Compare: tankless vs tank