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Propane tankless water heaters

Endless hot water where there is no natural gas line. Propane tankless water heaters suit rural homes, cabins, workshops, RVs and outdoor showers.

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Propane tankless water heaters, explained

A propane tankless water heater (also called an LP on demand water heater) works like a natural gas model: a burner fires the moment hot water flows and shuts off when you close the tap. Propane carries more energy per cubic foot than natural gas, and these units are popular wherever homes run on a propane tank.

Other names for the same thing include propane on demand water heater, on demand propane water heater, propane instant water heater, liquid propane water heater, lp tankless water heater and lp gas tankless hot water heater. All of them give you propane hot water on demand without a storage tank.

Types of propane tankless water heaters

Type Typical input Flow Use
Portable / outdoor 30,000–80,000 BTU 1.5–3 GPM Camping, outdoor showers, barns
RV / camper 40,000–60,000 BTU 1.5–2.5 GPM Travel trailers and motorhomes
Indoor whole house 120,000–199,000 BTU 5–11 GPM rated Primary home water heating
Outdoor whole house 120,000–199,000 BTU 5–11 GPM rated Mild climates, no indoor vent

Portable and outdoor-only units must never be used indoors. For RVs, see our RV and portable tankless water heaters.

Sizing a propane unit

Whole-house propane units are sized just like natural gas units: add the flow of fixtures used at the same time and check the flow at your winter temperature rise. A 199,000 BTU condensing unit typically delivers about 5–5.5 GPM at a 70°F rise. Use the sizing calculator for your home.

Propane supply and safety

An indoor propane tankless water heater must be a model listed for indoor use with a sealed vent; never bring an outdoor on demand lp gas water heater inside.

Propane vs electric tankless

Propane units deliver much more flow than electric units in cold climates and don't need a 150-amp electrical upgrade, but propane prices vary widely and you need a tank. Compare running costs in gas vs electric tankless water heaters.

What to look for on the product page

Fuel type (must say LP or propane), BTU input, rated GPM and the rise it was measured at, indoor or outdoor rating, vent type, UEF, freeze protection, warranty and condition. If anything is missing, ask us before you buy.

Frequently asked questions

How much propane does a tankless water heater use?

One gallon of propane holds about 91,500 BTU. A 150,000 BTU unit running at full fire uses about 1.6 gallons per hour, but it only burns gas while hot water is flowing. A typical family using 40–60 gallons of hot water a day may use roughly 8–15 gallons of propane a month for water heating, depending on climate, usage and efficiency.

Can I install a propane tankless water heater indoors?

Yes, if it is an indoor model installed with the manufacturer's approved direct-vent system and proper combustion air. Never use an outdoor or portable unit indoors. Read the venting guide.

Will a natural gas unit work on propane?

No, not without an approved conversion. Propane units use different gas valves and orifices. Buy the LP version, or use the manufacturer's conversion kit installed by a qualified technician.

What size propane tank do I need?

Small portable units can run from a 20 lb cylinder. Whole-house units usually need a larger tank, often 120–500 gallons, and a correctly sized regulator and line so the tank can vaporize enough gas in cold weather. Your propane supplier can size it.