Water heater tool review
Rinnai RX199iN Tankless Water Heater Review
Buy the Rinnai RX199iN if you have a large household, an existing gas supply with enough capacity, and you are tired of a tank that runs out halfway through the second shower, because 11.1 gallons per minute and a 0.98 uniform energy factor is close to the top of what a residential condensing unit does. Skip it if you were planning to install it yourself, because Rinnai explicitly does not recommend that, and skip it if your water is hard and you will not commit to flushing it, because scale is what kills these units.
Rinnai RX199iN Condensing Smart Sense Tankless Water Heater
about $1,533
Check price on AmazonAs an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Prices change; the figure above is what we last saw.
| Spec | Rinnai RX199iN Condensing Smart Sense Tankless Water Heater |
|---|---|
| Max flow | Up to 11.1 GPM, about 7 fixtures at once |
| Efficiency | UEF 0.98, condensing |
| Fuel | Natural gas or propane, Smart Sense gas control |
| Location | Indoor or outdoor with Versa Vent, RX-OVC cap required outdoors |
| Size | Rinnai describes it as the size of a small suitcase |
| Maintenance | Quick Flush feature for descaling |
| Warranty | 15 year heat exchanger, 5 year parts, 5 year labor, registration required within 90 days |
| Installation | Rinnai recommends a qualified technician and does not recommend self-installation |
Specs come from Rinnai's published product bullets returned by the Creators API. Price is for the unit only and is approximate.
What 11.1 gallons per minute buys you
Flow rate, not tank size, is the number that matters on a tankless unit. Rinnai publishes up to 11.1 GPM, which they describe as around seven fixtures simultaneously. In practice the achievable flow depends on how cold your incoming water is, because the unit has to raise it to temperature on the way through. The same heater delivers noticeably less usable flow in a northern winter than in a warm climate, which is why Rinnai publishes a ground water temperature map. If you have two bathrooms and a family that showers at the same time, this capacity is the reason to choose a 199,000 BTU class unit over a smaller one.
The costs that are not on the price tag
A condensing tankless heater needs its own venting, a gas supply capable of feeding a burner several times larger than a tank heater’s, a condensate drain, and often an upgraded gas meter. Those are the line items that make a real installed price look nothing like $1,533. Put your actual situation into the water heater replacement cost calculator before you decide, and read tankless vs tank water heater cost, which lays out where the payback period lands and where it never arrives. If your gas line has to be rerun, repipe costs give a sense of what plumbing work at that scale runs.
Indoor or outdoor, and why that matters
Rinnai’s Versa Vent design lets the same model install indoors or outdoors, with the RX-OVC vent cap required for an outdoor installation. Outdoors removes the venting run entirely, which is often the single biggest saving on the install, and it is common in mild climates. In a freezing climate an outdoor unit relies on its own freeze protection and therefore on uninterrupted power, so an outdoor install in a cold region is a decision to make with your installer rather than on price alone.
Hard water is the thing that kills these
Scale deposits on a tankless heat exchanger reduce flow, trigger error codes and eventually end the unit. The Quick Flush feature exists precisely because descaling is routine maintenance, not an occasional repair. If your water is hard, a softener upstream is not a luxury, and it is cheaper than a second heat exchanger. Our Fleck 5600SXT water softener review covers the usual answer, and the water softener cost calculator prices installation.
The honest weakness: the cold water sandwich and the maintenance commitment
Tankless heaters have a short delay between the tap opening and hot water arriving at temperature, and when a fixture is turned off and on again quickly you get a slug of cool water in between. Recirculation systems reduce it and cost more. The bigger commitment is maintenance: an annual descale is expected, not optional, and neglecting it in hard water will shorten the life of a unit whose whole value proposition is lasting longer than a tank. Anyone who has never flushed a water heater should be honest about whether they will start.
What owners consistently report
Published owner reviews are consistently positive about endless hot water and the compact size, and consistently point at installation as the hard part. Reports of trouble cluster around undersized gas lines and venting shortcuts rather than the heater itself. Owners who softened their water and flushed annually report years of trouble-free service; owners in hard water areas who did not are the ones filing error codes.
Who it suits
- Households of four or more with simultaneous hot water demand
- Homes with an existing gas supply that can carry the load
- Owners replacing a failed tank who want the space back
- Mild climates where an outdoor install avoids venting cost
Who should skip it
- Small households where a tank is cheaper to buy and run
- All-electric homes with no gas service
- Hard water homes with no softener and no intention of installing one
- Anyone hoping to self-install, which Rinnai advises against
Safety, stated plainly
Gas appliance installation is licensed, permitted trade work in most jurisdictions, and Rinnai itself recommends a qualified technician. Improper venting on a gas appliance is a carbon monoxide risk, which is the reason permits and inspections exist rather than a bureaucratic detail. Any home with combustion appliances needs a working carbon monoxide alarm on every level. Do not modify gas piping, vent routing or combustion air openings yourself, and treat any smell of gas as an evacuate-and-call situation.
Alternatives worth comparing
about $892
A smaller non-condensing unit at roughly half the price, the sensible choice for one or two bathrooms where 11.1 GPM is capacity you will never draw.
View on Amazonabout $1,410
The same condensing platform one size down, which fits a three or four person household without paying for peak capacity that never gets used.
View on Amazonabout $1,690
If you have no gas service or you are electrifying deliberately, a heat pump tank is the efficient answer and avoids venting and combustion entirely.
View on AmazonHow we researched this
We did not test the Rinnai RX199iN Condensing Smart Sense Tankless Water Heater in person, and nothing here is written as though we did. This review is drawn from the manufacturer's published specifications, the product's own documentation, and the consensus of published owner reviews, which is summarised as exactly that rather than presented as our own use. Specifications are sourced as noted under the table above, and prices are approximate and move. Cost figures elsewhere on this site are 2026 estimates, not quotes. This is researched information, not professional advice: anything touching electrical, gas, structural, roofing or hazardous material work should go to a licensed professional and through your local permitting process. For the cost side of this decision, see Tankless vs Tank.
Frequently asked questions
Can I install a Rinnai tankless water heater myself?
Rinnai states plainly that it does not recommend installing a water heater without a technician, and gas work is a licensed and permitted trade in most jurisdictions. Beyond the legal point, venting and gas line sizing errors on a gas appliance create a carbon monoxide risk. Hire a licensed plumber or gas fitter and pull the permit.
How many bathrooms will an 11.1 GPM tankless heater serve?
Rinnai describes this unit as serving about seven fixtures at once, which covers most family homes. The real answer depends on your incoming water temperature, because a heater raising 40 degree water to 120 degrees delivers less flow than the same unit raising 65 degree water. Cold-climate homes should size against winter conditions, not the headline number.
Is a tankless water heater worth the extra cost?
It depends on household size, gas price and how long you will stay. Tankless units cost more to buy and much more to install, and repay it through efficiency and a longer service life. A large household that draws a lot of hot water reaches payback; a two person household often does not. Our tankless vs tank cost comparison works through the arithmetic.
How often does a tankless water heater need flushing?
Annually is the usual recommendation, more often in hard water. Scale on the heat exchanger cuts flow and triggers faults, and it is the leading cause of premature failure. The Quick Flush feature on this model exists to make that routine, and a water softener upstream reduces how much scale forms in the first place.
Can this unit be installed outdoors?
Yes. Rinnai’s Versa Vent design supports indoor or outdoor installation, with the RX-OVC vent cap required for outdoor use. An outdoor install removes the venting run, which is often the biggest single saving. In freezing climates the unit relies on its own freeze protection and therefore on uninterrupted power, so discuss it with your installer.