Best Rinnai Tankless Water Heater

A hot shower should not become a race against an empty storage tank. Yet many families know the pattern well. One person showers, laundry begins, a second bathroom opens, and the warm stream starts losing its heat. A Rinnai tankless water heater removes the fixed storage limit by heating water as each faucet calls for it.

The Rinnai RXP199iN is the best Rinnai tankless water heater for most large homes. It combines an 11.1-GPM maximum rating, a built-in recirculation pump, natural-gas or propane operation, indoor or outdoor placement, and a 0.98 UEF rating. The RX199iN gives nearly the same heating power without the internal pump, while the RXP160iN is a better match for a smaller household.

Best Rinnai Tankless Water Heaters at a Glance

Best Overall: Rinnai RXP199iN

The Rinnai RXP199iN takes the top position because it places the company’s strongest residential heating output beside a factory-installed recirculation pump. It is made for large homes where several fixtures may open during the same hour.

The burner ranges from 15,000 to 199,000 BTU. A small handwashing draw calls for little heat. Two showers, a sink, and a washing machine can push the burner toward its upper limit.

This wide firing range helps the heater handle light and heavy water use without behaving like an oversized furnace. It burns only the gas needed for the water passing through the cabinet.

The RXP199iN reaches a maximum rated flow of 11.1 gallons per minute. That figure applies under favorable inlet conditions. Cold groundwater reduces the number of gallons the burner can heat each minute.

The built-in pump is the feature that places this model above the RX199iN. It can move warm water through a dedicated return pipe or a compatible crossover valve. Hot water then waits closer to distant bathrooms.

Rinnai’s Smart-Circ control can learn common water-use times and run the pump around those periods. The pump does not need to keep the plumbing loop warm throughout the day.

Recirculation can save water, but constant operation can burn more gas. Warm pipes release heat behind walls and beneath floors. A timed, learned, or button-operated cycle usually makes more sense than an always-on loop.

The RXP199iN works with natural gas or propane. The contractor sets the fuel during setup. This dual-fuel design can simplify ordering and future fuel changes.

The heater can mount indoors or outdoors with the proper Rinnai vent part. Outdoor placement removes a long indoor exhaust run. Cold-climate owners still need frost protection for every exposed water pipe.

The 0.98 UEF rating places the RXP199iN near the top of Rinnai’s residential line for fuel economy. Its condensing heat exchangers capture warmth that a basic unit sends outdoors.

Condensing operation creates acidic water inside the exhaust path. The installation needs a drain made from approved material. Some homes also need a neutralizer before the liquid enters the plumbing system.

Best match: A three- or four-bathroom house, a large family, or a home with long water lines.

Best Without an Internal Pump: Rinnai RX199iN

The Rinnai RX199iN shares most of the RXP199iN’s heating hardware. It has the same 199,000-BTU maximum input, 11.1-GPM maximum rating, dual-fuel setup, and 0.98 UEF rating.

The main difference is recirculation. The RX199iN can work with an approved external pump, but a pump is not fitted inside the cabinet.

This can save money when the home does not need recirculation. A compact house may have short pipe runs between the heater, kitchen, and bathrooms. Warm water may arrive quickly without a return loop.

The pump-free model also makes sense when an external recirculation system is already installed. Removing a working pump only to buy another one inside the heater would add cost without much gain.

The RX199iN can mount indoors or outdoors with the correct accessory. It also works with natural gas or liquid propane. Wi-Fi access allows temperature changes and operating checks from a phone.

The heater weighs less than the pump model. Both cabinets measure roughly the size of a carry-on suitcase, though valves and pipes need added wall room beneath the unit.

Best match: A large home with short plumbing runs or an existing external pump.

Best for a Medium Home with Recirculation: Rinnai RXP160iN

The Rinnai RXP160iN lowers the maximum burner input to 160,000 BTU and maximum flow to 9.0 GPM. It keeps the built-in pump found in the larger RXP199iN.

This model can suit a two- or three-bathroom home where two showers may run together. It can also feed a shower and kitchen faucet under colder inlet conditions, depending on fixture flow.

Buying the smaller RXP model can reduce the purchase price. It also avoids paying for burner capacity that a modest home may never call for.

The unit carries a 0.97 UEF rating. It works with natural gas or propane and can mount indoors or outdoors with the listed Rinnai setup.

The built-in pump is helpful when a bedroom suite sits at the opposite end of the house. A crossover valve may allow recirculation when the plumbing lacks a dedicated return line.

Do not select the RXP160iN only because the house has fewer residents. Two people with large rain showers may need more flow than a family of four using low-flow shower heads.

Best match: A medium home that wants factory recirculation without the price of the 199,000-BTU model.

Best Medium-Home Value: Rinnai RX160iN

The Rinnai RX160iN has the same 160,000-BTU ceiling and 9.0-GPM maximum rating as the RXP160iN. It removes the internal pump.

This is a good fit for a medium home with short water lines. It can also work in a house where the owner plans to add an external pump later.

The RX160iN carries a 0.97 UEF rating and supports natural gas or propane. Indoor and outdoor placement are available with the proper parts.

Its 15,000-BTU minimum firing rate helps with light draws. A small faucet can call for warm water without forcing the burner to run at a much higher setting.

The lower price leaves room in the budget for service valves, vent parts, a condensate neutralizer, or gas-pipe work. Those installation items often matter more than a small difference between heater prices.

Best match: A two- or three-bathroom home that does not need an internal recirculation pump.

Check the Rinnai RX160iN on Amazon.

Best for a Small Home: Rinnai RX130iN

The Rinnai RX130iN is the smallest model in the current RX group. It has a 130,000-BTU maximum input and a 7.1-GPM maximum rating.

This heater may suit a one- or two-bathroom home, a small cabin, a guesthouse, or a couple with modest simultaneous water use.

The RX130iN keeps many premium traits from the larger models. It works with natural gas or propane, mounts indoors or outdoors, connects to Wi-Fi, and carries a 0.97 UEF rating.

A smaller unit is easier on the purchase budget, but it still needs correct sizing. Cold groundwater may reduce output enough that two full-flow showers become too much.

Low-flow shower heads can make a clear difference. Two showers using 1.5 GPM each place a smaller load on the burner than two 2.5-GPM rain heads.

Best match: A small house, cabin, apartment, or guest suite where one main shower usually runs at a time.

Check the Rinnai RX130iN on Amazon.

Best Older Premium Model: Rinnai RU199iN or RU199iP

The Rinnai RU199 remains a good heater when local stock or installer familiarity makes it easier to buy than the newer RX line. The RU199iN is made for natural gas, while the RU199iP is made for propane.

Both versions reach about 11.0 GPM and use a 199,000-BTU maximum burner. Their 0.95 UEF rating is lower than the 0.98 rating of the RX199iN.

The RU199 works indoors and can use an approved external recirculation setup. It does not offer the same dual-fuel cabinet or indoor-outdoor flexibility found in the newer RX line.

The RU model may cost less when a dealer clears older stock. Check manufacturing date, warranty terms, included parts, and local repair access before buying.

Best match: A buyer who finds a strong local deal or has a contractor who works with the RU line every week.

RXP or RX: Which Rinnai Series Is Better?

Choose RXP when built-in recirculation matters. The pump sits inside the heater, which creates a cleaner wall setup and removes the need to select a separate pump.

Choose RX when hot water already arrives quickly or when the house has an external pump. The heating output remains the same within matching sizes.

The RXP199iN and RX199iN both reach 11.1 GPM. The RXP160iN and RX160iN both reach 9.0 GPM. The pump is the main dividing line.

How Many GPM Does Your Home Need?

Add the fixtures that may run 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 0.5 to 1.5 GPM.

Two 2.0-GPM showers create 4.0 GPM of demand. Add a 1.5-GPM kitchen faucet and the total rises to 5.5 GPM.

The heater must deliver that amount at the needed temperature rise. Maximum GPM alone does not tell the full story.

Why Groundwater Temperature Matters

Temperature rise is the gap between incoming cold water and the chosen outlet setting. 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. The burner can heat more gallons each minute because every gallon requires less added warmth.

This is why one Rinnai model can feed several fixtures in a warm southern region but fewer fixtures during a northern winter.

Does a Rinnai Tankless Heater Give Instant Hot Water?

The burner starts quickly, but warm water must still travel through the pipe. A bathroom far from the heater may wait for cold water already sitting in the line to leave.

A recirculation pump keeps warm water closer to distant fixtures. The RXP models place that pump inside the cabinet.

A crossover valve can create a return path through the cold line when no dedicated return pipe exists. The result is faster delivery, though the cold faucet may feel slightly warm for a brief period.

Natural Gas or Propane?

The current RX and RXP models work with natural gas or propane after correct setup. This removes the need to order a separate fuel-specific heater.

Natural gas reaches the home through a utility pipe. Propane sits in an outdoor tank and passes through a regulator before reaching the heater.

A large Rinnai can draw close to 199,000 BTU at full fire. The fuel line, regulator, and meter must supply that demand while other gas appliances are running.

Indoor or Outdoor Installation?

An indoor unit stays protected from rain, dirt, insects, and harsh cold. It needs approved intake and exhaust piping.

An outdoor setup removes the indoor vent run and frees utility-room wall space. Water pipes outside the cabinet remain open to freezing weather.

The Rinnai Versa-Vent accessory lets the RX cabinet work in either location. The contractor should select the site after checking pipe distance, weather, drainage, windows, doors, and service access.

Installation Costs Beyond the Heater

A tankless conversion may need new gas pipe, isolation valves, vent material, wall backing, electrical power, condensate tubing, a neutralizer, permits, and old-tank removal.

A simple tankless replacement can cost less than a full storage-tank conversion. Moving the unit or rebuilding the gas line can push the total above $2,000.

Get a complete installed price before ordering. Some contractors will not fit a heater bought by the homeowner, while others limit their labor warranty on customer-supplied equipment.

Warranty Coverage

Rinnai lists residential RX and RXP coverage at 15 years for the heat exchanger, five years for parts, and one year for labor under its stated terms.

Registering an eligible tankless heater within 90 days can extend labor coverage to five years. Local rules and the full warranty document control the final term.

Water quality, installation type, operating hours, recirculation, and commercial use may change coverage. Read the warranty tied to the exact model number.

Hard Water and Routine Care

Hard water can leave mineral scale inside the heat exchanger. The coating slows heat transfer and narrows the water path.

Many homes need periodic flushing with an approved descaling liquid. Isolation valves make the job easier.

Check the cold-water inlet screen for grit, rust, and pipe debris. Keep outdoor vent openings free from leaves, snow, insects, and nests.

A service visit should cover the burner, fan, seals, vent joints, condensate drain, and operating codes.

Common Buying Mistakes

The first mistake is buying from maximum GPM alone. Winter water temperature and fixture flow determine the real result.

Another mistake is paying for a built-in pump when all bathrooms sit close to the heater. The RX model may offer the same heating output for less money.

Some buyers overlook the gas line. A large tankless unit may need four or five times the burner input of an old storage heater.

Others expect hot water during a power outage. A gas Rinnai still needs electricity for ignition, controls, the combustion fan, and its pump.

Which Rinnai Tankless Water Heater Should You Buy?

Choose the Rinnai RXP199iN for the best mix of high output, built-in recirculation, dual-fuel operation, low gas waste, Wi-Fi access, and flexible placement.

Choose the Rinnai RX199iN when you need the same heating strength but do not need an internal pump.

Choose the Rinnai RXP160iN for a medium home that wants built-in recirculation. Pick the Rinnai RX160iN when short pipe runs make the pump unnecessary.

Choose the Rinnai RX130iN for a small home, cabin, or guesthouse. The older Rinnai RU199 remains worth buying when a trusted local installer offers a good price.

The best Rinnai tankless hot water heater should match winter groundwater temperature, fixture demand, fuel-pipe capacity, bathroom distance, vent location, and household schedule. When those pieces fit, a compact wall unit can keep showers warm without a large storage tank waiting to run cold.