Best LP Tankless Water Heater

A propane storage tank can run cold when the household is busiest. One shower ends, a second begins, laundry starts, and the kitchen faucet opens. The warm supply shrinks with every gallon. An LP tankless water heater removes that fixed storage limit by heating water only when a fixture calls for it.

The Rinnai RXP199iN is the best LP tankless water heater for most large homes. It supports liquid propane without a separate conversion kit, reaches 11.1 GPM under mild inlet conditions, includes a recirculation pump, and carries a 0.98 UEF rating. The Navien NPE-240A2 is a close rival for shorter faucet waits, while the Noritz EZ111DV Pro suits storage-tank replacement jobs.

Best LP Tankless Water Heaters at a Glance

Best Overall: Rinnai RXP199iN

The Rinnai RXP199iN takes the top position because it joins high heating output, propane flexibility, low fuel waste, and recirculation inside one compact cabinet. Rinnai’s adaptive gas valve lets the unit run on natural gas or LP without a separate conversion kit.

The model name ends in “N,” which may look like a natural-gas-only label. This newer Rinnai platform supports both fuels. The installer selects the correct fuel setting and places the required label on the cabinet.

Its burner ranges from 15,000 to 199,000 BTU. A light handwashing draw calls for a small flame. Two showers and a kitchen faucet may push the burner near its upper limit.

The 11.1-GPM maximum rating sounds large enough for almost any home, but inlet-water temperature changes the real result. Warm groundwater asks the heater to add fewer degrees. Cold winter water takes more burner power per gallon.

The built-in recirculation pump can shorten the wait at bathrooms far from the heater. It moves warm water through a dedicated return pipe or an approved crossover arrangement. The pump can run on a schedule, so the pipes warm before morning showers without staying hot all night.

Constant recirculation can burn extra propane. Hot pipes lose warmth inside walls, crawlspaces, and basements. Timed or demand-based operation usually gives a better balance between comfort and fuel use.

The RXP199iN carries a 0.98 UEF rating. Its condensing heat exchanger captures heat that a basic non-condensing unit sends outdoors. This process creates acidic condensate, so the installation needs an approved drain path.

Indoor and outdoor placement are available with the proper parts. Outdoor mounting can free utility-room space and remove the indoor exhaust run. Pipes outside the cabinet still need freeze protection in cold areas.

Best match: A large family, a three- or four-bathroom home, or a rural property with long plumbing runs.

Best for Faster Faucet Delivery: Navien NPE-240A2

The Navien NPE-240A2 is built for homes where waiting for hot water has become a daily irritation. Its ComfortFlow package combines an internal recirculation pump with a small buffer tank.

The buffer holds a small amount of warm water inside the cabinet. This helps reduce the brief cool patch that can appear when a fixture closes and opens again a few moments later.

Navien gives detailed output figures across a wide range of inlet conditions. The NPE-240A2 reaches 11.2 GPM at a 35°F rise, 8.7 GPM at a 45°F rise, and 5.6 GPM at a 70°F rise.

Suppose well water enters the heater at 50°F and the outlet setting is 120°F. The heater must add 70°F. Under that load, the usable flow sits near 5.6 GPM rather than the 11.2-GPM headline number.

A 5.6-GPM supply can feed two 2.0-GPM shower heads with room left for a smaller faucet. Three strong showers may ask too much during cold weather.

The propane burner ranges from 13,300 to 199,900 BTU. The primary and secondary heat exchangers use stainless steel, while the 0.95 UEF rating keeps fuel waste low.

The heater can mount indoors or outdoors. It needs a 120-volt electrical connection for ignition, the fan, pump, controls, and freeze protection.

Best match: A family that wants shorter faucet waits, smoother back-to-back use, and clear output figures for cold groundwater.

Best Connected LP Model: Rheem IKONIC RTGH-SR11i

The Rheem IKONIC RTGH-SR11i pairs a 199,900-BTU burner with a built-in pump and Wi-Fi. Rheem supplies a kit for conversion from natural gas to LP.

The largest IKONIC model reaches 11.2 GPM at a 35°F rise, 8.8 GPM at a 45°F rise, and 5.9 GPM at a 67°F rise. That cold-water figure gives the heater enough output for two low-flow showers in many homes.

The EcoNet phone connection lets the owner adjust temperature, check operation, receive fault alerts, and set pump times. This is useful when the heater sits in a basement, garage, exterior cabinet, or remote mechanical room.

Hot Start programming keeps the heater ready between closely spaced draws. A shower that pauses and restarts should face less of the cool-water sandwich found with some older tankless units.

The full-text front screen also makes setup easier. Instead of relying only on short number codes or tiny switches, the display presents operating details in plain language.

Rheem permits long vent runs with approved materials. The exact distance depends on pipe diameter and the number of bends. Every elbow acts like a small hill for the exhaust fan.

The written residential coverage lists 15 years on the heat exchanger after registration, five years on parts, and one year on labor. Installation, water quality, and usage conditions can affect coverage.

Best match: A connected home that wants phone access, pump scheduling, and strong output with cold inlet water.

Best for Replacing a Storage Tank: Noritz EZ111DV Pro

The Noritz EZ111DV Pro was made with tank replacement work in mind. Its hot and cold water fittings sit at the top, close to the location used by many storage heaters.

That arrangement can reduce pipe changes after the old tank is removed. It may also allow the heater to sit on the wall above the space once occupied by the storage cylinder.

The burner ranges from 12,800 to 199,900 BTU. Noritz lists flow from 0.4 GPM to 11.1 GPM, along with a 0.98 UEF rating.

The unit includes the parts needed for an approved natural-gas-to-LP change. The installer completes the conversion, selects the proper fuel setting, and checks combustion before use.

Dual stainless steel heat exchangers handle the heating work. A built-in display gives direct access to temperature and fault information, while Bluetooth helps with setup.

Indoor and outdoor placement are supported. The heater needs 120-volt power and a condensate drain.

Noritz advertises long heat-exchanger coverage for qualifying residential installations. Recirculation use and installation type can change the term, so the complete warranty should be read before purchase.

Best match: A homeowner replacing a 50- or 75-gallon propane tank who wants top water fittings and strong whole-house output.

Best Factory Propane Pick: Rinnai RU199iP

The Rinnai RU199iP arrives as a dedicated propane model. Buyers who prefer a clear factory LP configuration may find this easier than selecting a dual-fuel heater.

It reaches 11.0 GPM under mild inlet conditions and carries a 199,000-BTU maximum burner. The 0.95 UEF rating is lower than the newer RXP199iN, yet it remains well above common non-condensing units.

The RU199iP supports recirculation, though the standard cabinet does not contain the same pump package found in the RXP199iN. An approved external pump and control may be added.

Indoor placement protects the unit from weather. The heater needs approved intake and exhaust pipes, a condensate drain, electrical power, and enough wall room for service valves.

Wi-Fi access supports remote temperature settings and operating checks. The cabinet is about the size of a small suitcase, which frees the floor area left by an old tank.

Best match: A buyer who wants an established Rinnai model supplied for propane from the factory.

Check the Rinnai RU199iP on Amazon.

Best Lower-Cost Pick: Rinnai V94iP

The Rinnai V94iP is a dedicated propane model aimed at small and medium homes. It reaches 9.8 GPM under mild conditions and uses a burner that can rise to 199,000 BTU.

The lower purchase price comes with a 0.81 UEF rating. This is a non-condensing heater, so more heat leaves through the exhaust than with the premium models above.

Non-condensing exhaust runs hotter and often needs approved metal vent pipe. The heater does not need the same condensate drain arrangement as a condensing unit, but the vent can cost more when the run is long.

The V94iP works best in a home where one or two showers run together and the inlet water is not extremely cold. It may also suit a cabin with normal household plumbing and a large propane tank.

The 0.4-GPM activation level allows the burner to start during a light fixture draw. Wi-Fi support is also listed.

Best match: A smaller household that wants a dependable indoor LP heater at a lower purchase price.

Check the Rinnai V94iP on Amazon.

What Does LP Mean on a Water Heater?

LP means liquid propane. The fuel is stored as a liquid inside a pressurized outdoor tank. It turns into vapor before traveling through the regulator and fuel pipe toward the heater.

LP models are common on rural properties without natural-gas service. They also work well at cabins, farmhouses, mountain homes, and remote rental properties.

Natural gas and propane burn differently. A heater must use the proper fuel valve settings, burner setup, labels, and pressure. Never connect propane to a natural-gas-only appliance.

How Many GPM Does Your Home Need?

Add the fixtures that may run at the same time. A low-flow shower head may draw 1.5 to 2.0 GPM. A standard shower may reach 2.5 GPM. A bathroom faucet often uses less than 1.5 GPM, while a kitchen faucet may approach 2.0 GPM.

Two 2.0-GPM showers create 4.0 GPM of demand. Add a 1.5-GPM sink and the total reaches 5.5 GPM.

Compare that number with heater output at the required temperature rise. Do not compare it only with the largest GPM printed on the product page.

Why Temperature Rise Changes Output

Temperature rise is the difference between incoming water and the selected outlet temperature. Water entering at 50°F and leaving at 120°F needs a 70°F rise.

Water entering at 75°F needs only a 45°F rise to reach the same setting. The heater can warm more gallons each minute because every gallon needs less added heat.

This is why one heater can feed three fixtures in a warm region but only two during a northern winter. The burner remains the same. The cold water gives it a steeper hill.

How Large Should the Propane Tank Be?

A 199,000-BTU tankless heater can draw propane quickly at full fire. The outdoor tank and regulator must feed the heater while also serving the furnace, range, fireplace, dryer, pool heater, or generator.

Small portable cylinders are a poor match for permanent whole-house service. Cold weather reduces vapor production, and a nearly empty tank has less liquid surface available for vapor.

Many homes use a 250- or 500-gallon propane tank. The correct size depends on weather, refill access, total connected demand, and household use.

Ask the propane company to calculate tank and regulator capacity before the heater is fitted.

Will the Existing LP Pipe Work?

An old storage heater may use a burner near 30,000 to 50,000 BTU. A large tankless unit may call for nearly 200,000 BTU.

The old pipe may not carry enough fuel for that jump. Capacity depends on pipe diameter, material, length, regulator pressure, and the number of bends.

A weak fuel supply can cause ignition faults, poor heating, flame trouble, or trouble with nearby propane appliances.

The contractor should calculate the complete line from the regulator to every connected appliance. Replacing only the short section beside the heater may not fix a restriction farther away.

Do You Need Recirculation?

A tankless heater starts heating soon after a faucet opens, but the warm water must still travel through the pipe. A distant bathroom may wait for a minute or longer.

A recirculation pump moves warm water closer to the fixtures. A dedicated return pipe gives the cleanest setup, while a crossover valve can work in a home without one.

Timed or button-operated recirculation burns less propane than constant circulation. Pipe insulation also slows heat loss around the loop.

Condensing or Non-Condensing LP Heater?

A condensing heater uses a second heat exchanger to pull more warmth from the exhaust. This raises UEF and lowers vent temperature.

The cooler exhaust often permits approved plastic vent pipe. It also creates acidic condensate that needs a safe drain route.

A non-condensing heater normally costs less. Its exhaust is hotter and may need stainless steel vent pipe, which can become costly on a long indoor run.

For a busy whole-house installation, a condensing model often gives the stronger long-term package. A basic non-condensing model may suit a smaller home with a short vent run.

Installation Costs People Often Miss

The heater is only one part of the bill. Added work may include service valves, propane regulator changes, larger fuel pipe, vent materials, a condensate drain, electrical power, wall backing, permits, and old-tank removal.

A simple replacement may remain near the lower end of local labor prices. A full tank-to-tankless change can pass $2,000 after the heater and added work are counted.

A two-heater setup costs far more. It may need linked controls, extra valves, a larger regulator, more propane capacity, and added wall space.

Get a complete installed price before ordering. Some contractors will not fit equipment supplied by the homeowner.

Hard Water and Routine Care

Minerals can collect inside the heat exchanger. Hard water leaves a pale coating that slows heat transfer and narrows the water passages.

Many homes need periodic flushing with an approved descaling liquid. The interval depends on water hardness and daily demand.

Isolation valves make flushing easier. The cold-water inlet screen should also be checked for sand, rust, and pipe debris.

Keep vent openings free from leaves, nests, insects, snow, and dirt. Have the burner, fan, seals, vent joints, and condensate path checked on the schedule listed in the manual.

Common Buying Mistakes

The first mistake is choosing from maximum GPM alone. Cold-weather output gives a better picture of real shower capacity.

Another mistake is overlooking propane delivery. A large heater needs a suitable outdoor tank, regulator, and fuel pipe.

Some buyers forget that an LP tankless heater still needs electricity. The fan, ignition, controls, pump, and freeze protection stop during an outage unless backup power is available.

Others expect instant hot water at every fixture. A long plumbing run still causes a delay unless the home uses recirculation.

Never assume that any natural-gas model can be changed to propane. The exact model must permit the change, and the approved parts must be used.

Which LP Tankless Water Heater Should You Buy?

Choose the Rinnai RXP199iN for the best mix of propane flexibility, high flow, low fuel waste, built-in recirculation, Wi-Fi access, and indoor or outdoor placement.

Choose the Navien NPE-240A2 when short faucet waits, a buffer tank, and detailed cold-water flow figures matter most.

Choose the Rheem IKONIC RTGH-SR11i when phone access, pump scheduling, full-text controls, and strong cold-water output sit at the top of your list.

Choose the Noritz EZ111DV Pro for a storage-tank replacement with top-mounted water fittings and propane conversion parts.

Choose the Rinnai RU199iP when you prefer a factory propane configuration. Pick the Rinnai V94iP for a smaller home and a lower purchase price.

The best LP tankless hot water heater should match winter inlet temperature, simultaneous fixture demand, propane tank capacity, regulator output, pipe diameter, vent location, and recirculation needs. When those pieces fit, a compact wall heater can keep showers warm without a storage tank waiting to run cold.