Running out of hot water halfway through a shower can sour the whole morning. A propane tankless water heater avoids that problem by heating water only when a faucet opens. There is no large tank sitting in a closet and no limited reserve waiting to run dry.
The best propane tankless hot water heater must match the home’s peak demand, groundwater temperature, vent path, gas supply, and number of bathrooms. A large model may feed several fixtures in a warm region, yet the same heater may serve fewer showers during a cold winter. The printed maximum flow rate tells only part of the story.
High-End Pick: Rinnai RU199iP
The Rinnai RU199iP is the best propane tankless hot water heater for buyers who want strong whole-house output from a well-known maker. It delivers up to 199,000 BTU per hour and has a listed maximum flow rate of 11 gallons per minute. Its 0.95 Uniform Energy Factor places it among the better condensing propane units.
This model is made for indoor installation. It uses sealed combustion and can vent through approved plastic or polypropylene pipe. Since it is a condensing unit, it also needs a condensate drain. The acidic water produced during operation cannot be left to drip onto a floor or foundation.
The RU199iP is recirculation capable, Wi-Fi capable, and rated for ultra-low nitrogen oxide output. A recirculation setup can keep hot water closer to distant bathrooms, which cuts the long wait at the faucet. The pump, return line, control method, and operating schedule must suit the home.
This Rinnai works well for larger houses with three or four bathrooms when the fixtures do not all run at their maximum rate. In colder regions, its real output falls because the burner must add more heat to every gallon.
A full Rinnai installation may pass $2,000 after the heater, isolation valves, vent pipe, gas work, condensate drain, permit, and labor are added. Homes with an undersized propane line or regulator may face a higher bill.
Check Rinnai RU199iP listings on Amazon
Premium Pick with Built-In Recirculation: Noritz NRCR111DV
The Noritz NRCR111DV is a premium pick for homes where hot water takes too long to reach distant faucets. It has an integrated recirculation pump, a 0.98 Uniform Energy Factor, and a maximum rating of 199,900 BTU per hour.
Noritz lists a maximum flow rate of 11.1 gallons per minute. The unit can work with a dedicated return line or a crossover valve. Its automatic mode watches household use patterns and runs the pump near expected hot-water periods.
This can make a large home feel more comfortable. Instead of waiting beside the shower while cold water circles the drain, the user can receive warm water much sooner. Recirculation does use energy, so timer settings and on-demand controls matter.
The NRCR111DV has dual stainless steel heat exchangers and can be set up for indoor or outdoor use with the correct parts. It also has Bluetooth setup through the maker’s app and temperature settings from 100°F to 140°F.
Noritz lists a 15-year heat exchanger warranty for qualifying residential use. Parts and labor terms are shorter, and recirculation setups may carry added conditions. Read the full warranty before purchase.
Check Noritz NRCR111DV listings on Amazon
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Best Propane Tankless Water Heater Comparison
| Model | Maximum Input | Listed Flow | UEF | Best Use |
|---|---|---|---|---|
| Rinnai RU199iP | 199,000 BTU | Up to 11 GPM | 0.95 | Best overall indoor pick |
| Noritz NRCR111DV | 199,900 BTU | Up to 11.1 GPM | 0.98 | Built-in recirculation |
| Navien NPE-240A2 | 199,900 BTU | 11.2 GPM at a 35°F rise | 0.95 | Large homes and long pipe runs |
| Takagi T-H3-DV-P | 199,000 BTU | 8.4 GPM at a 45°F rise | 0.93 | Heavy residential use |
| Rheem RTG-95DVLP-3 | 199,900 BTU class | Up to 9.5 GPM | 0.82 | Lower-cost indoor replacement |
Navien NPE-240A2: Best for Large Homes
The Navien NPE-240A2 is built for homes with high hot-water demand and long plumbing runs. It can burn natural gas or propane when set up correctly by an approved installer. On propane, its input range runs from 13,300 to 199,900 BTU per hour.
Navien lists 11.2 gallons per minute at a 35°F temperature rise, 8.7 gallons per minute at a 45°F rise, and 5.6 gallons per minute at a 67°F rise. These numbers give buyers a better view than a single maximum rating.
The model has an internal recirculation pump and a small buffer tank. The buffer tank helps reduce short bursts of cold water between closely spaced hot-water calls. This can be useful when someone turns a shower off, pauses for a moment, and turns it back on.
The NPE-240A2 uses stainless steel heat exchangers. It can be mounted indoors or outdoors when the installation follows the maker’s directions. Indoor setups use direct venting through approved 2-inch or 3-inch material.
Navien states that consumer purchases through online retail channels can void warranty coverage. Buy this model through an approved local company and have that company handle the installation. The dealer route may cost more at the start, but it gives the homeowner a clearer service path.
Takagi T-H3-DV-P: Best for Heavy Residential Use
The Takagi T-H3-DV-P is a 199,000 BTU indoor condensing propane heater. It is a strong match for larger homes, hydronic heating arrangements, domestic recirculation loops, salons, and light commercial spaces.
Takagi rates it for 8.4 gallons per minute at a 45°F rise and 5.4 gallons per minute at a 70°F rise. Those figures make it easier to judge winter output. A home that needs three showers during cold weather should pay close attention to the 70°F rise number.
The primary heat exchanger uses a commercial-grade copper alloy. The secondary exchanger uses 316L stainless steel. This pairing gives fast heat transfer while allowing the heater to capture more energy from the exhaust.
The T-H3-DV-P can vent through approved PVC, CPVC, polypropylene, or stainless vent material. It is also certified for high-altitude use up to the maker’s stated limit, though burner settings and output may change with elevation.
Takagi lists a 15-year limited heat exchanger warranty for qualifying residential installations and five-year limited parts coverage. Commercial coverage is shorter. Registration, water conditions, installation method, and service records can affect a claim.
Check Takagi T-H3-DV-P listings on Amazon
Rheem RTG-95DVLP-3: Best Lower-Cost Whole-House Pick
The Rheem RTG-95DVLP-3 is a non-condensing indoor propane tankless heater with a listed flow rate of up to 9.5 gallons per minute. It offers plenty of hot water for many two-bathroom and three-bathroom homes without the higher purchase price of a premium condensing model.
Rheem uses Hot-Start Programming to reduce cold bursts between back-to-back hot-water calls. The unit also has a compact cabinet that measures about 24 inches high, 13 inches wide, and 10 inches deep.
Its 0.82 Uniform Energy Factor is lower than the ratings of the condensing picks above. More heat leaves through the exhaust, and the vent pipe must handle hotter gases. The tradeoff is that a non-condensing heater does not produce the same steady stream of acidic condensate.
This model can be a sensible replacement when a home already has compatible tankless venting. Reusing an old vent is allowed only when the new heater and vent maker approve it. A plumber must inspect the material, diameter, length, joints, and termination.
Rheem lists a 15-year heat exchanger warranty, five-year parts coverage, and one-year labor coverage for qualifying use. The heater can also accept an added recirculation pump kit.
Check Rheem RTG-95DVLP-3 listings on Amazon
How to Size a Propane Tankless Water Heater
Do not choose a heater by bathroom count alone. Count the fixtures that may run during the busiest part of the day. A shower may use 1.5 to 2.5 gallons per minute. A bathroom faucet may use about 1.0 to 1.5 gallons per minute. A washing machine or dishwasher can add another demand spike.
Next, find the temperature rise. Subtract the incoming cold-water temperature from the desired outlet temperature. Water entering at 50°F and leaving at 120°F needs a 70°F rise.
A heater’s maximum flow rating is often measured with a low temperature rise. That number can shrink fast in winter. An 11 GPM model may deliver closer to 5 or 6 GPM when it must add 67°F to 70°F.
A two-person home with one shower running at a time may be comfortable with a 140,000 to 160,000 BTU model. A family that uses two showers at once may need 180,000 to 199,900 BTU. Large homes with three simultaneous showers may need the biggest residential model or two linked heaters.
Condensing vs. Non-Condensing Propane Models
A condensing heater captures more heat from its exhaust. This lowers exhaust temperature and raises fuel use performance. It can often vent through approved plastic pipe, which may reduce vent cost in some homes.
Condensing models create acidic water that must flow to a drain. Some areas call for a neutralizer before the condensate enters the plumbing. The neutralizer contains media that needs replacement over time.
A non-condensing heater sends hotter exhaust outdoors through rated metal venting. It usually costs less to buy and has no condensate drain. The vent can be more expensive, especially when the run is long.
The better choice depends on the room, existing vent, drain location, local rules, and planned years of ownership. A condensing model may cost more on day one but burn less propane over a long service life.
Indoor vs. Outdoor Installation
An indoor propane tankless heater is protected from rain, wind, direct sun, and freezing air. It needs approved intake and exhaust piping. The installer must also follow clearance rules around windows, doors, corners, meters, and air openings.
An outdoor model removes the indoor vent run. This can cut labor and free wall room inside the house. It still needs gas, water, electricity, and safe clearances.
Freezing weather is the main concern with an outdoor heater. Built-in freeze protection works only while power and gas remain available. Exposed pipes can still freeze. Pipe insulation, heat cable, valves, and a proper drain plan may be needed.
Outdoor models fit warm regions best. Homes in cold areas often do better with an indoor unit unless the outdoor location has strong freeze protection.
Propane Supply and Gas Line Size
A large tankless heater can burn close to 200,000 BTU per hour at full fire. The propane tank, regulator, and gas pipe must deliver that amount while other gas appliances are running.
A furnace, range, clothes dryer, fireplace, and water heater may all draw propane during the same winter hour. The gas company or plumber should total the connected load and check pipe length before installation.
An undersized line can cause ignition trouble, flame failure, low output, or fault codes. Do not assume the pipe that fed a 40-gallon tank heater can feed a 199,000 BTU tankless model.
The regulator also matters. Propane pressure must stay within the heater’s allowed range under load. Static pressure can look fine while pressure drops badly when several appliances start.
Installation Cost
A simple replacement may cost less when gas, water, venting, power, and drainage are already in the right places. A first-time tankless conversion often costs much more.
The bill may include the heater, isolation valves, service ports, gas pipe, regulator work, vent material, condensate parts, electrical outlet, wall bracket, permit, old-tank removal, and labor.
A premium whole-house propane tankless water heater installation can pass $2,000 with ease. Long vent runs, masonry work, a larger propane line, or two linked heaters can raise the price much further.
Ask for a written installed price before buying the unit. A low online heater price can lose its appeal when the vent and gas work are added later.
Care and Service
Minerals can coat the heat exchanger like scale inside a kettle. Hard water speeds this buildup and can reduce flow or heating ability. Most makers call for periodic flushing with an approved descaling liquid.
Isolation valves with service ports make flushing much easier. Add them during installation rather than paying a plumber to cut into the pipes later.
Clean the inlet screen, inspect the vent termination, check the condensate drain, and look for water or gas leaks. Outdoor models also need clear air openings with no leaves, snow, nests, or debris.
Homes with hard water may benefit from scale control or water softening. The selected method must suit the heater and local water conditions.
Common Buying Mistakes
Buying by Maximum GPM Alone
The largest flow number may be measured with warm incoming water. Check performance at the temperature rise your home faces during winter.
Ignoring Propane Capacity
A large burner cannot work properly when the tank, regulator, or pipe is too small. Have the full gas load checked before ordering.
Forgetting the Condensate Drain
Condensing heaters release water during operation. The drain path and neutralizer can add cost to an indoor job.
Choosing the Wrong Installation Location
An outdoor unit can freeze. An indoor unit needs a safe vent route. Pick the location only after a plumber checks both options.
Buying Before Finding a Service Company
A tankless heater may need brand-specific parts and trained service. Confirm that a nearby company works on the selected brand.
Final Verdict
The Rinnai RU199iP is the best overall propane tankless hot water heater for most larger homes. Its 199,000 BTU burner, 11 GPM maximum rating, 0.95 UEF, indoor condensing design, and recirculation support give it a strong mix of output and comfort.
The Noritz NRCR111DV is the better premium pick when built-in recirculation matters. Its 0.98 UEF and 11.1 GPM maximum rating place it near the top of the residential class.
The Navien NPE-240A2 works well for large homes that need an internal pump and buffer tank. Buy it through an approved dealer because online retail purchases can affect warranty coverage.
The Takagi T-H3-DV-P suits heavy residential demand and light commercial use. The Rheem RTG-95DVLP-3 offers a lower-cost path for buyers who do not need a condensing unit.
Before ordering, compare winter flow, propane supply, vent type, drain access, service support, and full installation price. The best heater is the one that can feed the busiest hour without starving the shower or overloading the gas line.