Rinnai RU98iN Sensei Tankless Water Heater

The Rinnai RU98iN Sensei Tankless Water Heater is the entry-level condensing tankless in Rinnai's residential lineup — sized for 1-bathroom homes, ADUs, condos, and small households. 5.4 GPM peak flow. 120,000 BTU modulating condensing burner. 0.96 UEF. 15-year heat exchanger warranty. Same condensing technology and Control-R 2.0 platform as the bigger Sensei siblings, just calibrated for lower demand and lower upfront cost.

Headline specifications

• Type: indoor condensing tankless, natural gas (LP-convertible)
• Maximum flow rate: 5.4 GPM at 35°F rise
• BTU input: 10,300–120,000 BTU/h (modulating)
• Energy Factor (UEF): 0.96
• Min activation flow: 0.4 GPM
• Venting: PVC, CPVC, polypropylene; up to 100 ft
• Warranty: 15-year heat exchanger, 5-year parts, 1-year labor
• Dimensions: 26" H × 18" W × 11" D, ~53 lbs
• Built-in WiFi via Control-R 2.0 app

Who this model is for

The RU98iN is calibrated for 1–2 person households, single-bathroom homes, ADUs, condos, and small homes with modest hot-water demand. 5.4 GPM at a 35°F rise handles one shower plus a bathroom sink simultaneously without temperature drop. It's also a strong pick for warm-inlet regions (Sun Belt) where the modest BTU input handles single-bathroom whole-house demand year-round.

For cold-inlet regions, effective flow drops to about 3.5 GPM in winter — adequate for one shower but tight for any simultaneous demand. Two-bathroom homes in cold regions should size up to the RU130iN.

Where it beats the alternatives

Vs RU130iN ($1,299): RU98iN saves $200–$250 for households that don't need 7.5 GPM. Same warranty, same WiFi, same install footprint. The right pick when you're sure your demand stays under 5 GPM.

Vs Rinnai V53iLP ($799) — propane equivalent: If you have natural gas service, the RU98iN's condensing efficiency wins on running cost. If you're on propane (rural / off-grid), the V53iLP is the equivalent unit.

Vs Bosch Greentherm 5300 ($849): Bosch at 5.3 GPM non-condensing (0.81 UEF). The Rinnai's 0.96 UEF condensing efficiency saves $300+ in gas over 10 years; the 15-year warranty beats Bosch's 10. Worth the $250 premium for long-horizon owners.

Vs Navien NPE-150S2 ($1,099): Navien at 7 GPM standard condensing without buffer tank. Spec-equivalent on warranty (15 years), Navien has slightly more capacity. Choose Rinnai for service network; Navien if 7 GPM fits the install better.

Where it falls short

5.4 GPM ceiling is the obvious limit. Two simultaneous showers will drop output temperature. For any household that occasionally needs >5 GPM, size up.

Cold-water sandwich without buffer tank — same as all Sensei models.

Annual descaling required for warranty maintenance. 3/4" gas line and PVC venting required for retrofit installs.

Install considerations

Standard Rinnai Sensei install profile. The lower 120K BTU input means the gas-line capacity question is less critical than on the larger Sensei models — 1/2" line can sometimes work at short runs, though 3/4" is recommended throughout. Venting still requires PVC schedule 40.

Install cost: $900–$1,600 typical for like-for-like swap; $2,400–$4,000 for tank-to-tankless conversion.

Maintenance

• Annual descaling (mandatory for warranty)
• Annual inlet filter clean
• Firmware updates via Control-R 2.0

Bottom line

The Rinnai RU98iN Sensei is the right-sized entry condensing tankless for small US households (1–2 people), single-bathroom homes, ADUs, and condos. Buyers who don't need 7+ GPM peak capacity get the same Rinnai quality, warranty depth, and WiFi platform at the lowest tankless price point in the Sensei lineup. For households with growing demand or two simultaneous shower scenarios, the RU130iN is the next step up. Click through to Amazon for live pricing.