Brands

Rinnai

The other name most homeowners have already heard for gas tankless, and the one manufacturer of the six that publishes usable flow figures at real inlet temperatures rather than only a headline number. Also makes heat pump water heaters, and says plainly that it does not make electric tankless, which settles a question a lot of people arrive with.

Worth shortlisting if

You are converting to gas tankless and want recirculation built in
You want the flow you are buying stated at your own inlet temperature
An experienced Rinnai installer works your area
You are replacing an existing Rinnai unit
You want one manufacturer across tankless and heat pump

Look elsewhere if

Your retrofit geometry is awkward and connection layout matters
Nobody local services the brand well
You will not keep up with annual descaling
You were sold on a headline flow figure you will never see
A storage tank is the better technology for your house anyway

The 11.1 figure is not the flow you will get

The RX199 is advertised at 11.1 gallons per minute. Rinnai’s own sizing guide puts the same unit between 5.2 and 6.0 GPM once the incoming water is somewhere in its winter range of 45°F to 55°F and you want it delivered at 120°F. The headline figure describes a much smaller temperature rise than any house here asks for in January.

Six gallons a minute is a useful amount of hot water, roughly two showers at once with a little to spare. Five is closer to one shower and a sink. The trouble is only that neither one is eleven, and sizing a house on eleven is how people end up with a unit that runs cold when two taps open on a cold morning. Ask your installer for the flow at your design rise, in writing, and check they have used the cold end of the range rather than the mild one.

What we have verified, and what we have not

Warranty terms, model lines and installer programmes change without notice, and they vary by model, registration and installation type. Rather than publish a number that quietly goes stale, each row shows its own state.

The Rinnai brand record

Technologies made: Condensing gas tankless (SENSEI RX and RXP, plus the RUCS and RUS families), non-condensing gas tankless (RE and REP), and heat pump water heaters (REHP, 50, 65 and 80 gallon). Rinnai states it does not make electric tankless.
Source: Rinnai residential tankless water heater rangeChecked 7 Aug 2026
Tankless flow, by inlet temperature: RX199 and RXP199 are rated 11.1 GPM at the headline condition. At a 120°F setpoint the same unit delivers about 5.0 GPM from 42°F incoming water, 5.7 GPM from 52°F, 6.2 GPM from 57°F and 8.1 GPM from 72°F.
Size on the cold end of the winter range, not its middle. A unit sized on the summer number runs cold in January, and a unit sized on a mild January runs cold in a hard one.
Source: Rinnai RX199iN product data and ground water sizing guideChecked 7 Aug 2026
Recirculation: RX is recirculation capable. RXP adds a built-in pump and Smart-Circ. On the non-condensing side, REP includes a pump and RE does not.
Source: Rinnai RE and REP model seriesChecked 7 Aug 2026
Warranty, RX199 residential: 15 years heat exchanger, 5 years parts, 1 year labour. The heat exchanger term also carries a 12,000 burn hour cap, and whichever limit arrives first is the one that applies.
A burn hour cap is not the same thing as a 15 year warranty. A large household running a recirculation loop accumulates burn hours far faster than a small one, so the practical term is shorter for exactly the houses that use the unit hardest.
Line level, not model level. Registration and promotional labour extensions vary. Ask for the warranty document for the exact model you are quoted.
Source: Rinnai RX199iN warranty summaryChecked 7 Aug 2026
Heat pump sizing and efficiency: REHP comes in 50, 65 and 80 gallon nominal sizes, rated at 46, 61 and 74 gallons, with first hour ratings of 73, 80 and 91 gallons. Published UEF runs about 3.75, 3.90 and 4.00 across the three, which is at the strong end of the current market. Runs on 208 to 240V single phase, 30A breaker, 21.5A maximum, with a 3/4 inch condensate connection.
Source: Rinnai REHP50, REHP65 and REHP80 product dataChecked 7 Aug 2026
Heat pump ambient limits: VerifyRinnai’s public product material and a retrieved spec sheet disagreed slightly on the upper ambient limit, 109°F against 107°F. Use the installation manual for the exact model rather than any brand wide number, including this one.
Warranty, REHP residential: Product material summarises 1 year labour and 10 years parts, and the current spec sheet also identifies tank coverage at 10 years. The manual controls.
Source: Rinnai REHP50 product page and spec sheetChecked 7 Aug 2026
Installer programme: Rinnai PRO and ACE PRO. We found no blanket requirement that an installer hold either, so treat programme status as a signal that the brand is serviced in an area rather than as a rule about who may fit it.
Source: Rinnai Find a PRO locatorChecked 7 Aug 2026
Local programme coverage: Programme coverage exists in the Modesto area. At least one local company held ACE PRO status on our check date, which is the useful part: it says the brand is serviced here rather than shipped in and left to a generalist. We do not publish company names, because a directory entry is a snapshot and a listing is not a recommendation from us.
We will not describe any installer as authorised, certified or trained except where that exact status appears in the manufacturer’s own current directory, and we do not introduce homeowners to companies on the strength of a directory listing alone.
Parts availability, Central Valley: Mixed to strong. PACE Supply publicly carries Rinnai tankless products and parts. Exact Modesto and Ripon shelf stock still needs checking.
Source: PACE Supply Rinnai brand listingChecked 7 Aug 2026
Known failure modes: Rinnai's current diagnostic guide documents Code 25 for a condensate pump error or a clogged or frozen drain. That is a description of a failure category, not evidence of how often it happens, and we will not present it as one.
Source: Rinnai tankless diagnostic code guideChecked 7 Aug 2026
Consumer financing: Available at manufacturer level, which makes Rinnai one of only two brands in our set where that is true today. Worth asking about, and worth comparing against whatever your installer offers rather than assuming the manufacturer programme is the cheaper of the two.
Source: Rinnai consumer financingChecked 7 Aug 2026

Navien or Rinnai

We converted both manufacturers’ published flow tables onto one basis, because they are not published in the same units, and at a Central Valley winter the two headline models land 0.12 GPM apart. The full head to head is here, including the two different ways that shared 15 year warranty gets cut short.

Rinnai or Noritz

These are the two most common gas tankless shortlists in this market after Navien, and the research does not name an overall winner, because there isn’t one. What decides it is your house rather than the badge.

Rinnai when the RX or RXP meets your design flow and you value the recirculation feature set or a nearby service path. Noritz when the retrofit geometry is the hard part: top mounted water connections, flex vent compatibility and bundled replacement kits are built for exactly that problem, and its Central Valley parts position is the strongest of the six.

Ask your installer these before committing to the brand

What flow does this model give at my winter inlet temperature?
How many of these have you installed in the last year?
Who services it when it throws a code, you or someone else?
Are parts held locally, or ordered in?
Does a recirculation loop change my warranty or my burn hours?
Would you put this brand in your own house, and why?

Check whether tankless is right first Compare all brands