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Best Propane Tankless Water Heater

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

Propane (LP) tankless water heaters are the dominant choice for off-grid and rural-no-natural-gas installations. The combustion side is nearly identical to natural-gas tankless; the difference is in the fuel orifice sizing and the connection to the propane regulator. Most major brands offer LP variants of their natural-gas models — Rinnai, Navien, Rheem, Bosch, Eccotemp, Marey.

Top picks

Whole-house indoor LP: Rinnai RU199iP (the LP version of RU199iN)

199K BTU LP, UEF 0.96, condensing, indoor mount with PVC venting. The premium choice for a rural home with propane supply and demand for multiple bathrooms. About $4,200 installed (slight premium over NG version due to propane regulator requirements).

Whole-house outdoor LP: Rinnai V94eP

199K BTU LP, exterior wall-mount. Eliminates indoor venting. Common in rural California, Arizona, Texas where exterior install is code-acceptable and saves indoor space. About $3,600 installed.

Outdoor portable LP (camp/cabin): Eccotemp L10

75K BTU, 2.6 GPM peak. Battery-fired ignition — no 120V required. Stand-alone outdoor mount with included shower kit. About $370 unit. Right for camping, hunting cabins, outdoor showers.

Bigger outdoor portable LP: Eccotemp EM-7.0

7 GPM peak, larger burner. Sized for a primary outdoor shower at a more developed cabin. About $700 unit.

Whole-house indoor LP mid-tier: Bosch Therm 940 ESO-LP

175K BTU LP, condensing, indoor mount. The Bosch alternative to Rinnai/Navien. Strong build quality, smaller US service network. About $3,400 installed.

Marey LP outdoor compact: Marey GA10LP

75K BTU LP outdoor portable. Budget alternative to Eccotemp L10. About $250 unit, 1-year warranty (versus Eccotemp's 2-year). Acceptable for occasional-use outdoor showers.

Propane vs natural gas — what differs

Propane and natural gas burn similarly but the fuel orifice and regulator differ. Practical implications:

  • Energy density difference: propane delivers ~2.5× the energy per cubic foot of natural gas. Lines and orifices are sized smaller for propane to deliver the same BTU output.
  • You cannot field-convert easily: a natural gas tankless cannot be converted to propane without manufacturer-supplied conversion kit and recertification. Order the LP version explicitly.
  • Fuel cost varies: propane typically costs 1.5–2× more per BTU than natural gas in regions where both are available. In propane-only rural areas the higher cost is unavoidable.
  • Tank vs underground line: propane systems use a tank on the property (typically 250–500 gallons buried or 100–500 gallons above-ground). Refueling delivery 2–4× per year for a typical household.

Propane install realities

Beyond the typical tankless install considerations:

  • Propane regulator sizing: the regulator at the tank must be sized for the tankless's BTU demand. 199K BTU requires a high-output regulator (typically 1/2 PSI or two-stage 10 PSI/0.4 PSI configuration depending on line length).
  • Line sizing: 1/2" copper or 3/4" black iron lines from regulator to unit, with sizing per propane gas code (lower-pressure systems require larger pipes).
  • Permit + propane inspector: some jurisdictions require both the building permit AND a separate inspection by the propane provider before activation. Plan for this in scheduling.
  • Tank sizing for tankless load: a 199K BTU tankless consumes propane at high rate during operation. Households with marginal-sized tanks (120 gallon) may need to upsize to ensure adequate refueling interval. Most installations use 250+ gallon tanks.

Propane operating cost

For a household of four, 60 gallons hot water daily, at $2.80/gallon propane:

  • Tankless propane (UEF 0.96): approximately $42/month.
  • Tank propane (UEF 0.62): approximately $65/month.
  • Electric heat-pump (if available): $13/month.

If electric utility service is available at the install location, heat-pump electric is dramatically cheaper than propane tankless. Pure propane areas (truly off-grid) face propane costs as the only option; tankless minimizes them versus tank-style.

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