RV tankless water heater — Truma AquaGo vs Furrion, BTU, flow rate, freeze protection reality

The promise of 'endless hot water' collides with physics

Traditional 6- or 10-gallon tank heaters (Suburban, Atwood) store a fixed volume, recover in 20-40 minutes after depletion, and waste propane keeping water hot even when unused. Tankless units fire a modulating burner only on demand once flow exceeds the sensor threshold, heating water as it passes through a compact heat exchanger. The promise is no recovery wait and no tank to run dry. The collision is immediate when inlet water is cold or flow is low.

Per Truma AquaGo comfort plus technical specifications (2026), nominal input is 20,000 to 60,000 BTU/h stepless, target outlet ~120°F (49°C), water volume inside the appliance only 0.35 gal (1.3 L), operating pressure limit 65 psi. Minimum ignition flow is approximately 0.4 GPM (1.5 L/min). Furrion's FWH09AFA-AM series publishes 60,000 BTU/h input with 2.4 GPM output capacity and explicit antifreeze protection on designated models. Both are certified to ANSI Z21.10.3 / CSA 4.3 for RV use — not residential whole-house units.

A 10 gal tank at 120°F supplies roughly one full shower plus dishes before the burner must reheat the entire volume. A 60k BTU tankless can sustain flow indefinitely provided the BTU input, inlet temperature, and flow rate stay inside the performance envelope. Cross the envelope and the unit either cycles off or delivers lukewarm water. Pre-LLC PickRV will require hosts to disclose the exact make/model and the documented winterization procedure on every tankless-equipped listing; renters book the physics, not marketing.

• ›Truma AquaGo: 20k-60k BTU/h input, 0.35 gal internal volume, 65 psi max inlet, 10.5-14 in. wc gas
• ›Furrion 2.4 GPM model: 60k BTU/h, 0.32 GPM minimum flow per manual, 35-70 psi nominal plumbing, 11-14 in. wc gas
• ›Outlet target both brands: ~120°F (49°C) at rated conditions; actual at tap varies with pipe length and mixing
• ›Both units certified ANSI Z21.10.3 for recreational vehicles only — never marine, space heat, or permanent dwellings

BTU, flow, and inlet temperature math that actually governs output

The industry sizing formula (widely referenced by DOE and manufacturers) for the water-side heating rate is BTU/hr = GPM × ΔT × 500, where ΔT is the temperature rise from inlet to target outlet and 500 approximates 8.33 lb/gal × 60 min/hr. This is the thermal energy the water absorbs. The appliance input BTU rating must cover that plus losses; real efficiency on RV propane units is rarely 100% once altitude, combustion air quality, and scale are factored.

Example at sea level, 60°F inlet (typical mild day), 120°F target (ΔT 60°F), 2.0 GPM shower: water-side demand = 2.0 × 60 × 500 = 60,000 BTU/hr. A full-modulation 60k input Truma or Furrion unit can hold it if combustion is clean and the unit is not already scaled. Drop inlet to 40°F (mountain spring or winter shoulder): ΔT 80°F yields 80,000 BTU/hr water-side demand. The same 60k unit now supports only ~1.5 GPM before outlet temp falls. At 8,000 ft the propane burner itself loses output (roughly 4% per 1,000 ft in many gas appliances; exact derate curve is installation-specific and not always published by the RV OEM). The result is lower GPM or lower temp at the same setting.

Furrion manuals note high-altitude use considerations and require proper orifice/ventilation per local code. Truma documentation emphasizes that the stepless controller adjusts output based on measured flow and inlet temp, but the maximum is still the 60k ceiling. Renters who expect residential 2.5+ GPM multi-head showers in cold source water or at elevation will be disappointed unless the rig has two parallel units or the listing explicitly states capacity under those conditions. Verify current data in the specific unit's 2026 manual before relying on it for a multi-person trip.

Truma AquaGo comfort / comfort plus — exact 2026 published data and modes

Truma AquaGo basic (DLE60B), comfort (DLE60C), and comfort plus (DLE60CP) share the same core burner and heat exchanger. Comfort and plus add circulation pump and recirculation line provisions for faster hot-water availability at distant taps. Per the US Operating Instructions (Truma Corp / Forest River component manual), water connections are 1/2 in. NPT, gas manifold pressure 1.3-10 in. wc, nominal voltage 12 V DC <2.5 A running, <0.045 A standby. Weight 34.2 lb, dimensions 12.5 × 12.5 × 15.5 in.

Operating modes on control-panel models: ECO (saves propane, appliance kept >41°F / 5°C with burner), COMFORT (stand-by heat >102°F / 39°C for quicker response), OFF, ANTIFREEZE (with optional electric kit, 12 V keeps appliance >41°F without propane), and CLEAN (decalcification cycle). The Easy Drain Lever on the front allows tool-free draining and houses the reusable inlet filter. Decalcification uses six Truma tablets inserted into the filter; the control panel walks the user through the cycle and requires an 8-gallon rinse. The unit must be powered on and the system depressurized before lever operation.

Freeze protection language is explicit: "Winter operation will not protect the RV’s entire water system. Water lines, faucets, water tanks and the external water valves and the vehicle must be heated separately." Basic models must be fully winterized below 39°F (4°C) ambient; comfort models can run in ECO or COMFORT down to -4°F (-20°C) ambient when the RV is designed for winter use, power and propane are maintained, and the water system is pre-bleed so the circulation pump can operate. The electric antifreeze kit accessory extends protection without propane consumption for the heater only.

• ›Min flow ignition: ~0.4 GPM (1.5 L/min); below this the burner does not fire and cold water passes
• ›Pressure relief valve: CSA-certified 100 psi (6.9 bar) Truma replacement only; never plug or tamper
• ›Scald warning in manual includes table: 120°F (49°C) ~5 minutes to skin damage; 155°F (68°C) 1 second; always mix at tap and test before shower
• ›Decalcification required in hard-water regions; frequency per water quality, not calendar

Furrion 2.4 GPM / 60k BTU tankless — retrofit fit and documented limits

Furrion (Lippert brand) tankless models (FWH09AFA-AM and variants) are designed as direct footprint replacements for many 10-gal tank cutouts on North American RVs. Published output capacity 2.4 GPM at 60,000 BTU/h input. Gas 11-14 in. wc, water plumbing 35-70 psi nominal, minimum flow for proper operation 0.32 GPM per the user manual (CCD-0005507 Rev 03-31-25). The unit includes a wall thermostat with LED display, flame indicator, low-flow error reporting, and Vortex technology that premixes to reduce temperature fluctuations and scald risk.

Antifreeze protection is listed as a feature on FWH09AFA and FWH09AFA-AM models; the manual contains a dedicated Antifreeze Function section and a Winterizing Water Heater procedure that includes optional bypass valve installation to reduce antifreeze volume needed for the coach. Hard Water and Decalcification section exists; routine filter cleaning and pressure safety valve maintenance are required. The manual states the appliance is for RV installation only and certified ANSI Z21.10.3 / CSA 4.3-2019. It is not for marine or space-heating use.

High-altitude use is called out as a consideration; proper installation per NFPA 1192 and local codes is the installer's responsibility. Like Truma, the unit will not heat the entire coach's fresh system against freeze — only its own small internal volume when the antifreeze function is active and conditions allow flow.

• ›2.4 GPM rated output at 60k BTU — real sustained GPM drops with cold inlet or altitude exactly as physics predicts
• ›0.32 GPM minimum per Furrion manual (slightly lower threshold than Truma's 0.4 GPM)
• ›Vortex premix + thermostat for consistency; still requires user mixing at tap for final comfort and safety
• ›Retrofit door kits available; measure existing cutout before ordering

Propane consumption, altitude, and scale — the numbers renters actually experience

Because the burner runs only when flow is present, propane use per shower is typically 20-30% lower than a tank unit that maintains temperature 24/7. Real consumption is gallons of propane = (water-side BTU required) / (propane energy content × efficiency). Propane liquid is approximately 91,500-92,000 BTU per gallon. At 80% effective transfer, a 12-minute 1.8 GPM shower with 70°F rise consumes roughly 0.11-0.14 gal propane. A family of four doing two showers plus dishes daily at mild inlet temps might see 0.8-1.2 gal/day from the water heater alone — before stove, furnace, or fridge. Cold inlet or high flow pushes it higher.

Altitude derate is physics, not optional. At 5,000-7,000 ft many RV propane appliances lose noticeable capacity; 8,000+ ft common in western parks compounds the effect on both BTU delivery and combustion. Listings in high-elevation states should note any observed performance limits. Hard-water scaling (Southwest, Texas Hill Country, parts of Florida and the Midwest) coats the exchanger, reduces heat transfer, and eventually triggers over-temp faults. Truma's semi-automated tablet process and Furrion's documented descaling are annual or more frequent chores in aggressive water; skipping them voids performance claims and can damage the unit. Pre-trip packets on PickRV will include the host's last descaling date and water-hardness notes where relevant.

Freeze protection reality — unit modes vs entire fresh-water system

Both manufacturers are unambiguous: the heater's antifreeze or winter modes protect only the small volume inside the appliance and immediate heat exchanger. The fresh tank, pump, PEX or poly lines, fixtures, city-water inlet, and any low-point drains remain vulnerable. Truma: "If the appliance is not to be used in frost conditions, you must winterize the appliance... Winter operation will not protect the RV’s entire water system." Furrion manuals dedicate sections to full winterizing procedures, bypass valves, and antifreeze fluid volumes when the coach will sit unheated.

Practical winter use therefore requires the RV itself to be winter-rated (insulated, heated tanks or skirts, heat tape on exposed runs, or active 12 V / propane heat in the water bay). For unheated storage below freezing, full winterization with RV antifreeze (or blow-out + antifreeze in traps) is still mandatory on the whole system. Cracked exchangers and burst lines from owners who trusted only the "freeze protected" label on the heater are a documented field failure mode. PickRV pre-LLC will surface the host's explicit winterization protocol and any tank-heater or skirting equipment in the listing details so renters know the actual cold-weather envelope before booking shoulder or winter dates.

Safety certifications, pressure relief, scald risk, and code context

Both Truma and Furrion units carry ANSI Z21.10.3 / CSA 4.3 certification for recreational vehicle installation. NFPA 1192 (Standard on Recreational Vehicles, adopted by RVIA) governs fuel systems, plumbing, and fire/life safety in the coach; propane delivery pressure at the appliance must stay within the 10.5-14 in. wc (or 11-14 in. wc) window specified by the heater. Excess-flow valves, proper venting clearances (minimum distances from openings, intakes, propane fills), and CO detectors are required by the standard and by the appliance instructions. Tampering with the pressure relief valve or bypassing safeties voids certification and warranty.

CPSC and DOE guidance on scald prevention is consistent: residential and RV water heaters have been voluntarily preset toward 120°F (49°C) since the late 1980s. At 120°F, time to serious burn is measured in minutes; at 140°F+ it drops to seconds. The Truma manual reprints a scald-time table sourced to classic thermal injury studies and warns to test water and mix at the tap. Furrion's Vortex technology and thermostat are intended to stabilize delivery, but final temperature at the point of use is still the renter's responsibility. Never disable the pressure relief or operate without a functioning CO detector in the RV.

• ›Pressure relief: 100 psi rated, replace only with OEM certified part; never plug
• ›Gas: propane only; butane or >10% butane mixes prohibited by both manuals and NFPA 1192 context
• ›Venting: keep intake/exhaust clear of snow, ice, debris, awnings, or stored items — obstructed combustion = CO risk
• ›CO + LP detectors required; test before every trip per RVIA and manufacturer guidance

How PickRV surfaces tankless reality on listings and at pickup

Tankless is a premium feature that changes the hot-water math but does not eliminate water-system discipline. Once verified hosts are live, every listing with a tankless unit will disclose: exact make and model (Truma AquaGo Comfort Plus, Furrion FWH09AFA-AM, etc.), presence/absence of electric antifreeze kit or hybrid element, last documented descaling date if known, and the host's written winterization procedure (bypass valves, antifreeze volumes, heat sources, or full blow-out). Pre-trip packets will include the same data plus any observed performance notes from the host (e.g., "maintains 2.0 GPM at 50°F inlet at sea level; drops to 1.6 GPM at 6,500 ft").

At pickup the renter will verify the exterior access door is secure, the control panel or thermostat powers up, and the host demonstrates the winterization steps if the season or destination requires them. The honest framing that will appear in all materials: you receive on-demand hot water within the flow-rate, inlet-temperature, altitude, and maintenance limits of the specific unit; you remain responsible for the rest of the fresh-water system, propane supply, and code-compliant winterization. Data and procedures are as of 2026 manufacturer publications — always verify against the current manual supplied with the rig.