Best Propane On Demand Water Heater

A storage tank can feel like a melting block of ice during the morning rush. Each shower takes another slice, and the last person may receive little more than a cold trickle. A propane on-demand water heater removes that fixed storage limit. It heats water as faucets open, then stops burning fuel when the water shuts off.

The Rinnai RXP199iN is the best propane on demand water heater for most large homes. It reaches 11.1 GPM under favorable conditions, carries a 199,000-BTU burner, includes a recirculation pump, and has a 0.98 UEF rating. The Navien NPE-240A2 is another strong choice for fast delivery, while the Noritz EZ111DV Pro suits owners replacing a large storage tank.

Best Propane On Demand Water Heaters at a Glance

Best Overall: Rinnai RXP199iN

The Rinnai RXP199iN takes the top position because it combines high propane output, strong fuel efficiency, recirculation, and flexible mounting in one compact cabinet. The heater can burn propane after the approved setup has been completed by a qualified installer.

Its burner ranges from 15,000 to 199,000 BTU. That broad firing range helps the heater respond to both light and heavy demand. Washing hands calls for a small flame. Two showers and a kitchen faucet ask for far more heat.

Rinnai lists a maximum flow of 11.1 GPM. This number represents mild inlet conditions rather than the flow every household will receive. Cold groundwater lowers the number of gallons the burner can heat each minute.

The built-in recirculation pump can shorten the wait at distant fixtures. It moves warm water through a dedicated return pipe or an approved crossover setup. This can stop gallons of cold water from washing down the drain while someone waits for the shower to warm.

Recirculation should run only when needed. A pump that runs all day keeps the pipes warm, but those pipes release heat into walls and floors. Timed or on-demand operation cuts that waste.

The 0.98 UEF rating places the RXP199iN among the stronger residential propane choices. Its condensing heat exchanger pulls warmth from exhaust gas before that gas leaves the house. This creates acidic condensate that must drain through approved material.

The heater can sit indoors or outdoors with the proper vent accessory and setup. Outdoor mounting can save room inside a cabin or utility area. Exposed pipes still need freeze protection in cold regions.

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

Best for Recirculation Comfort: Navien NPE-240A2

The Navien NPE-240A2 is a strong pick for households that dislike long faucet waits and brief cold patches. Its ComfortFlow system combines an internal pump with a small buffer tank.

The buffer tank holds a small amount of heated water inside the cabinet. This helps smooth the change between short water draws. For example, someone may stop a shower while applying shampoo and restart it moments later. The buffer can soften the cool burst that sometimes follows.

Navien publishes flow at three temperature rises. The NPE-240A2 can reach 11.2 GPM at a 35°F rise, 8.7 GPM at a 45°F rise, and 5.6 GPM at a 67°F rise.

Those figures give buyers a realistic view of winter output. Water entering at 50°F and leaving at 120°F needs a 70°F rise. The usable flow will sit closer to the 67°F-rise number than the maximum number printed in large type.

A 5.6-GPM supply can feed two low-flow showers with some room left for a small faucet. Three full shower heads may ask too much during a cold winter morning.

The propane burner ranges from 13,300 to 199,900 BTU. Stainless steel primary and secondary heat exchangers handle the repeated heating cycle and the moisture found inside a condensing heater.

The NPE-240A2 can mount indoors or outdoors. It needs a 120-volt electrical connection for ignition, the fan, controls, freeze protection, and pump operation.

Best match: A household that wants fast delivery, steady shower heat, and clear flow figures for colder water.

Best Connected Pick: Rheem IKONIC RTGH-SR11i

The Rheem IKONIC RTGH-SR11i combines a 199,900-BTU maximum burner with an internal recirculation pump and built-in Wi-Fi. The supplied conversion part permits an approved change from natural gas to propane.

Rheem rates the largest model at 11.2 GPM with a 35°F rise, 8.8 GPM with a 45°F rise, and 5.9 GPM with a 67°F rise. That last figure gives it a little more cold-water capacity than several close rivals.

The internal pump can move warm water through a return line. Rheem’s controls allow scheduled pump operation, so the loop can warm before morning showers and remain off during quiet hours.

Hot-start programming keeps the heater ready between nearby draws. This helps reduce the short cool patch that may appear when a faucet closes and opens again.

Wi-Fi access allows temperature changes, operating checks, pump schedules, and alerts from a phone. The front display also uses full text rather than a row of unexplained blinking lights.

Rheem permits approved PVC, CPVC, or polypropylene vent systems. Long vent runs are possible, though every elbow reduces the allowed straight distance.

The residential warranty lists 15 years for the heat exchanger, five years for parts, and one year for labor under the written terms. Registration, water quality, installation type, and recirculation use may affect coverage.

Best match: A connected home that wants pump scheduling, strong cold-water output, and easy control from a phone.

Best for Replacing a Storage Tank: Noritz EZ111DV Pro

The Noritz EZ111DV Pro is built for owners moving from a large propane storage tank to on-demand water heating. Its hot and cold connections sit at the top, much like those on a traditional tank.

That placement can reduce plumbing changes during a replacement. The installer may be able to reuse more of the existing pipe route rather than rebuilding every line beneath the new wall unit.

The current EZ111DV Pro reaches 11.1 GPM and uses a burner that ranges from 12,800 to 199,900 BTU. It carries a 0.98 UEF rating and uses two stainless steel heat exchangers.

The unit ships with the part needed for an approved propane conversion. Bluetooth setup helps the installer select the correct fuel setting and check operating data.

Noritz lists a long heat-exchanger warranty for this model. The exact term can change with recirculation use and installation conditions, so the written warranty should be read before purchase.

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

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

Best Noritz Model with a Pump: NRCR111DV

The Noritz NRCR111DV adds an integrated recirculation pump to the company’s 11.1-GPM platform. It can use a dedicated return pipe or an approved crossover valve.

Its recirculation modes include automatic household pattern tracking, a manual timer, and on-demand operation. On-demand mode starts the pump shortly before hot water is needed, rather than keeping the pipes warm all day.

The heater supports long return loops. Noritz lists up to 200 feet with half-inch pipe or up to 500 feet with three-quarter-inch pipe under stated conditions.

Burner input ranges from 12,800 to 199,900 BTU, while the listed UEF is 0.98. Indoor and outdoor mounting are supported.

This model carries a shorter heat-exchanger warranty than the pump-free EZ111DV Pro. Recirculation places more operating hours on a heater, which is one reason warranty terms may differ.

Check the Noritz NRCR111DV on Amazon.

Best match: A broad home with distant bathrooms and no desire to add a separate recirculation pump.

Best Factory Propane Model: Rinnai RU199iP

The Rinnai RU199iP is a dedicated propane model. Buyers who do not want a field fuel conversion may prefer this clear model code and factory propane configuration.

Its burner ranges from 15,000 to 199,000 BTU. Rinnai lists a maximum flow of 11.0 GPM and a 0.95 UEF rating.

The RU199iP is made for indoor installation. It supports recirculation, though the pump is not built into the standard unit. An approved external pump and control package can be added.

Wi-Fi access is available for temperature control and system checks. The cabinet measures about the size of a small suitcase, which frees the floor area once used by a storage tank.

The newer RXP model has a higher UEF rating and an internal pump, but the RU199iP remains a sensible choice when a dedicated propane model is easier to buy locally.

Check the Rinnai RU199iP on Amazon.

Best match: A buyer who wants a high-output Rinnai model supplied for propane from the factory.

How Many GPM Does Your Home Need?

Add the fixtures that may operate at the same time. A low-flow shower may use 1.5 to 2.0 GPM. A standard shower head may use up to 2.5 GPM. A bathroom faucet often draws less than 1.5 GPM, while a kitchen faucet can approach 2.0 GPM.

Two 2.0-GPM showers create 4.0 GPM of demand. Add a 1.5-GPM kitchen faucet and the household needs 5.5 GPM at the chosen outlet temperature.

Do not compare that total with the maximum GPM alone. Compare it with the heater’s output at the required temperature rise.

A large propane model may deliver more than 11 GPM when the incoming water is warm. The same unit may provide close to 5.5 or 6 GPM when it must add nearly 70°F to every gallon.

Why Temperature Rise Matters

Temperature rise is the difference between incoming water and the selected outlet setting. Water entering at 45°F and leaving at 120°F needs a 75°F rise.

Water entering at 70°F only needs a 50°F rise. The burner can heat more gallons per minute because each gallon requires less added warmth.

This explains why a tankless heater behaves differently in Maine and Florida. The burner has the same strength, but the colder home gives it a much steeper hill.

How Large Should the Propane Tank Be?

A 199,000-BTU heater can draw fuel quickly when it reaches full fire. The propane tank and regulator must feed the heater while also serving the furnace, range, dryer, fireplace, generator, or pool equipment.

Small cylinders are a poor match for a permanent whole-house heater. Cold weather lowers vapor production inside the tank, and a nearly empty tank has less surface area available for vapor.

Many rural homes use a 250- or 500-gallon tank. The right size depends on climate, refill access, household demand, and every propane appliance on the property.

Ask the propane company to calculate tank and regulator capacity. The installer should calculate pipe size from the regulator to the heater.

Will the Existing Propane Line Work?

An old storage heater may use a burner near 30,000 to 50,000 BTU. A large on-demand model can approach 200,000 BTU. The old line may be too narrow for that jump.

Fuel-pipe capacity depends on diameter, material, length, pressure, and the number of bends. Demand from other appliances also counts.

A weak supply can cause ignition faults, low outlet temperature, noisy combustion, or trouble with nearby appliances. Replacing only the final few feet of pipe may not solve a restriction farther upstream.

Do You Need Recirculation?

A tankless heater begins producing hot water soon after a faucet opens, but the heated water must still travel through the plumbing. A distant bathroom may wait a minute or longer.

A recirculation pump moves warm water closer to the faucet. A dedicated return line gives the best result, while a crossover valve can work in homes without one.

Timed or button-operated recirculation usually wastes less fuel than constant operation. Pipe insulation also helps the loop hold its heat.

Indoor or Outdoor Installation?

Indoor models stay protected from rain, dust, and severe cold. They need approved intake and exhaust pipes, along with a condensate drain.

Outdoor mounting removes the indoor vent run and frees utility-room wall space. The heater still needs propane, water, electricity, and safe clearance from windows and doors.

Cold-region owners must guard exterior pipes from freezing. The heater’s built-in freeze protection cannot protect every exposed pipe around it.

Installation Costs People Miss

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

A simple replacement may stay near the lower end of local labor rates. A full storage-tank conversion can pass $2,000 once the heater and added work are counted.

A two-unit system can cost far more. It may need linked controls, a larger regulator, more wall room, extra vent parts, and greater propane capacity.

Get a written whole-job price before ordering the unit. Some contractors will not install equipment purchased by the homeowner.

Hard Water and Routine Care

Minerals can collect inside the narrow heat-exchanger passages. Hard water leaves a pale shell that slows heat transfer and restricts flow.

Periodic flushing with an approved descaling liquid may be needed. The service interval depends on water hardness and household use.

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

Keep exterior vent openings free from leaves, nests, insects, snow, and dirt. Have the burner, fan, seals, vent joints, and condensate path checked according to the owner manual.

Common Buying Mistakes

The most common mistake is buying by maximum GPM alone. Flow at the winter temperature rise gives a better picture of real shower capacity.

Another mistake is ignoring propane delivery. A large burner needs a suitable tank, regulator, and pipe.

Some buyers forget that a propane tankless heater still needs electricity. The fan, control board, ignition system, pump, and freeze protection cannot work during an outage unless backup power is available.

Others expect instant hot water at distant faucets. Recirculation or a nearby point-of-use heater is needed when pipe length causes the delay.

Do not buy a natural-gas-only model with the idea of converting it later. Use only the approved fuel setup listed for the exact model.

Which Propane On Demand Water Heater Should You Buy?

Choose the Rinnai RXP199iN for the best mix of high flow, low fuel waste, recirculation, Wi-Fi access, and mounting flexibility.

Choose the Navien NPE-240A2 when fast delivery, a buffer tank, and clear cold-water flow figures matter most.

Choose the Rheem IKONIC RTGH-SR11i when connected controls, pump scheduling, and strong flow at a 67°F rise sit at the top of your list.

Choose the Noritz EZ111DV Pro for a storage-tank replacement with top water connections. Pick the Noritz NRCR111DV when you want a factory-installed pump and flexible recirculation modes.

Choose the Rinnai RU199iP when you prefer a model supplied in a dedicated propane configuration.

The best propane tankless hot water heater should match winter inlet temperature, simultaneous fixture demand, propane tank capacity, regulator output, pipe size, and vent location. When those pieces fit, the small wall-mounted cabinet can keep showers warm without a large storage tank waiting to run cold.