Propane Water Heaters

Propane (LP gas) water heaters use the same fundamental hardware as natural gas water heaters — the only difference is the orifice size and burner air-fuel ratio calibrated for propane's higher BTU/cu ft. Most US residential gas water heaters ship as natural gas with an LP conversion kit (~$30–$80 part) that the installer applies during install. Propane water heaters serve rural US homes without natural gas service, mountain properties, off-grid homes, and many manufactured homes.

Propane vs natural gas — the cost math

Per BTU, propane typically costs 1.5x to 2x more than natural gas in US markets. Specific 2026 pricing varies by region — propane delivery cost, tank lease, regional availability all play in. For a typical 3–4 person household:

• Natural gas atmospheric tank: $280–$380/year
• Propane atmospheric tank: $450–$650/year
• Propane condensing tankless: $280–$420/year (the efficiency gains partially close the per-BTU gap)
• Heat pump: $170–$240/year (the math winner where install fits)

Where natural gas service is available, it's nearly always cheaper. Propane is the answer when natural gas isn't.

Propane-compatible water heater models

Most residential gas water heaters from the major brands are LP-convertible:

• Rheem Performance Platinum 50G — ships natural gas, LP conversion kit available separately
• AO Smith Signature Premier 50G — same LP conversion path
• Bradford White Defender 50G — plumber-channel with LP conversion
• Propane-dedicated models — some brands offer pre-converted LP variants (different model number) for installs where the conversion is done at the factory

Tankless propane options

All major condensing gas tankless brands offer LP variants — the burner and combustion air are calibrated at install. Top picks:

• Rheem RTGH-95DVLN — LP-convertible
• Rinnai RU199iN Sensei — LP-convertible
• Navien NPE-240A2 — LP-convertible

For rural / off-grid installs on propane, condensing tankless makes more economic sense than atmospheric tanks — the higher upfront cost is partially recouped through ~$200/year in operating savings vs an atmospheric LP tank.

LP propane conversion

Conversion involves:

1. Installing the smaller LP orifice (provided in conversion kit)
2. Adjusting the gas valve regulator to LP pressure (typically 11" w.c. for LP vs 7" for natural gas)
3. Verifying combustion with a combustion analyzer — propane burns slightly hotter and requires verification of complete combustion to prevent CO production
4. Updating the data plate to reflect LP configuration

Conversion must be done by a licensed gas technician. Self-conversion voids warranty and creates real safety risk (CO production from incomplete combustion).

LP venting considerations

Propane's slightly higher CO output makes proper venting critical:

• Atmospheric LP: chimney must be in good condition; CO detector mandatory in the install area
• Power-vent LP: PVC venting acceptable; same as natural gas
• Direct-vent LP: sealed combustion is the safest configuration for LP
• Condensing LP tankless: PVC venting; condensate drain required

Propane tank sizing for water heater service

A typical residential 500-gallon propane tank holds enough for 4–6 months of water-heater-only use, longer when combined with propane space heating. For water-heater-only off-grid installs, 250-gallon tanks are common. Tank lease vs purchase decisions depend on the regional propane delivery market.

Bottom line on propane water heaters

For rural US homes without natural gas service, propane water heaters are the standard answer. The hardware is identical to natural gas (same Rheem / AO Smith / Bradford White lineup, LP-converted at install). Operating cost is meaningfully higher than natural gas but lower than electric resistance. For long-horizon owners, propane condensing tankless or — even better — heat pump water heater are the operating-cost winners. The heat pump option is especially compelling for rural homes since it eliminates propane delivery dependency entirely.