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Curated Best-Of List

Best Tankless Water Heaters

3 expert-curated picks ranked by performance, value, and long-term reliability

"Tankless water heaters" — plural — usually reflects a buyer surveying the category rather than zeroing in on a specific brand or model. This list maps the tankless landscape by fuel type and demand profile, with the canonical pick for each segment.

Gas tankless — the dominant residential tankless category

Premium condensing (UEF 0.93+): Rinnai RU199iN, Navien NPE-240A, Rheem RTGH-95DVLN

199K BTU class. Condensing design captures latent heat from flue gas for UEF 0.93–0.96. PVC venting. Right answer for households doing major renovation or new construction where the install premium fits the project budget. About $4,000 installed.

Non-condensing (UEF 0.82): Rinnai RL199iN, Rheem RTG-90, Takagi T-H4J

180–199K BTU at lower UEF. Stainless B-vent venting (cheaper retrofit when existing chimney is in place). Right answer for like-for-like replacement of an aging non-condensing tankless or an atmospheric tank with reusable chimney. About $2,800 installed.

Mid-BTU (140–180K) — smaller homes and propane: Rinnai RL75iN, Rheem RTGH-72

Sized for 1–2 bathroom homes with sequential use. Insufficient capacity for overlapping demand. Lower install cost (smaller gas line requirements, sometimes 1/2" line suffices). About $2,400 installed.

Electric tankless — limited but important segment

Whole-house electric (200A service): EcoSmart ECO 27, Stiebel Eltron Tempra 36

27 kW+ units that can deliver one shower at a time in cold climates or two showers in warm climates. Lifetime warranties on the leading brands. About $1,800 installed.

Mid-size electric (100–200A service): Rheem RTEX-18, EcoSmart ECO 18, Stiebel Eltron Tempra 24

18–24 kW units that fit most 100A panels with load calc. Single-bathroom focus, southern climate. About $1,400 installed.

Point-of-use electric: EcoSmart POU 3.5 / POU 6, Bosch Tronic 3000T

Small units for remote single fixtures. Eliminate long hot-water waits at distant sinks. About $300–$500 installed.

Outdoor and RV tankless

Cabin / off-grid outdoor: Eccotemp L10, Marey GA10LP, Camp Chef Hot Water Pro

Battery-fired propane units that work without 120V power. Outdoor mounting only. About $300–$500 unit.

RV in-trailer: Furrion FWH09BL, Suburban IW60, Atwood/Dometic equivalent

Tankless units sized for travel-trailer plumbing. Replace 6-gallon storage tanks in newer RVs. About $600 unit.

Picks by household demand profile

Demand profileRight tankless
4+ bathrooms, overlapping useRinnai RU199iN or two parallel units
3 bathrooms, occasional overlapRinnai RU199iN or Navien NPE-240A
2 bathrooms, sequential use (warm climate)Rheem RTEX-18 (electric) or RL75iN (gas)
1 bathroom, single occupantEcoSmart ECO 11 or Rheem RTEX-13
Remote fixture onlyEcoSmart POU 6 or Bosch Tronic 3000T
Outdoor cabinEccotemp L10 or Marey GA10LP
RV replacementFurrion FWH09BL or like-for-like RV-OEM

Installation realities common to all tankless

Every tankless retrofit involves three line items beyond the unit cost:

  • Gas line upsize ($400–$1,200) for gas tankless if existing line is 1/2".
  • Venting ($500–$1,500) — PVC for condensing, stainless B-vent for non-condensing, sealed direct-vent for outdoor exterior mounts.
  • Electrical ($150–$400 gas, much more for whole-house electric tankless).

The unit is typically 30–40% of the total project cost. Budget the install carefully and verify the gas line size before purchase — undersized gas line is the most-skipped install check in tankless retrofits.

3 products
$949 – $1,795
Updated May 2026

Quick Comparison

# Product Brand Rating Price
1 Rinnai RU199iN Sensei Tankless Water Heater Rinnai 4.8 Check current price Amazon
2 Rheem Performance Platinum 50-Gallon Gas Water Heater Rheem 4.6 Check current price Amazon
3 AO Smith Signature Premier 50-Gallon Gas Water Heater AO Smith 4.5 Check current price Amazon