Rinnai RUR98iN Sensei+ Recirculation Tankless Water Heater

The Rinnai RUR98iN Sensei+ Recirculation Tankless Water Heater is the model that solves the two main complaints about tankless water heaters: the cold-water sandwich, and the wait time for hot water at distant fixtures. It's the standard Sensei platform — 9.8 GPM peak flow, 180,000 BTU condensing burner, 0.93 UEF, 15-year warranty — with an integrated recirculation pump that pre-circulates hot water through a dedicated return loop, eliminating wait time at far-away fixtures and dramatically reducing the cold-water sandwich phenomenon.

Headline specifications

• Type: indoor condensing tankless with integrated recirculation pump
• Maximum flow rate: 9.8 GPM at 35°F rise
• BTU input: 18,000–180,000 BTU/h (modulating)
• Energy Factor (UEF): 0.93 (slightly lower than non-recirc Sensei due to pump energy use)
• Integrated recirculation pump with timer + on-demand button
• 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, ~62 lbs
• Built-in WiFi with recirculation scheduling via Control-R 2.0 app

The recirculation difference

A standard tankless heater fires when you open a hot tap — but hot water still has to travel from the unit to the fixture. In a typical US home with the water heater in the basement and the master bath upstairs, hot water travels 40–60 feet through pipe before it reaches the showerhead. While that water travels, you're standing under cold water. The "cold-water sandwich" makes this worse on intermittent draws.

The RUR98iN's integrated recirculation pump runs (on a schedule, on-demand, or via the Control-R 2.0 app button) to push hot water through a dedicated return loop back to the heater. The pipe stays warm. When you open the tap, hot water arrives in 1–2 seconds instead of 30–60.

The trade-off: the recirculation pump uses about 20 watts when running, and circulating hot water through the loop loses heat to the pipe walls — typical efficiency cost is 2–3% over a year of normal use. For households where the convenience matters (no more waiting for hot water at the master bath, no more wasted water down the drain while you wait), the small efficiency tradeoff is worth it.

Who this model is for

• Homes with long pipe runs from the water heater to the farthest fixture (>30 feet)
• Households frustrated by hot-water wait time at distant bathrooms or kitchens
• Buyers who would otherwise install an external recirculation pump anyway
• Drought-conscious households wanting to eliminate water wasted while waiting for hot
• Multi-story homes with master suites two floors above the water heater

For short pipe-run homes (kitchen and bathroom both within 15 feet of the water heater), the recirculation feature adds cost without much benefit — the non-recirc RU199iN at $1,645 or the RU180iN at $1,499 is the cost-saver.

Where it beats the alternatives

Vs RU199iN + aftermarket recirculation pump: the aftermarket route (RU199iN at $1,645 + Grundfos UP15-10SU at $250 + dedicated return-line plumbing) totals $2,200+ and requires a return-line install. The RUR98iN integrates the pump cleanly and offers app-controlled scheduling that aftermarket pumps lack.

Vs Navien NPE-240A2 ($1,799): Navien has ComfortFlow buffer tank but no integrated recirculation. To get the same on-demand hot-water experience, buyers add an aftermarket pump. The RUR98iN combines both features in one box.

Where it falls short

Requires a dedicated return line from the farthest fixture back to the water heater. If your home doesn't have one (most don't), you need to install it — adding $500–$1,500 to the plumbing scope. Older homes with crawl spaces or accessible basements can usually accept the return line; finished walls and slab foundations make it expensive.

Energy cost of recirculation. Running the pump 24/7 wastes energy. Use the timer or on-demand button to limit operation to peak-use windows.

Slightly lower UEF (0.93 vs 0.96 on non-recirc Sensei) reflects the recirculation pipe heat loss. Over 10 years, that's ~$80–$150 in additional energy cost — usually worth the convenience.

Install considerations

Same Sensei install requirements (3/4" gas line, PVC venting, 120V outlet, service valves) plus a dedicated return line from the farthest fixture back to the water heater. Many modern homes are plumbed for recirculation; older homes may not be. Get a plumber's assessment of the recirculation install scope before committing.

Install cost: $1,500–$2,800 if the return line exists; $2,500–$5,000 if it needs to be installed.

Maintenance

• Annual descaling (warranty requirement)
• Inlet filter clean annually
• Schedule recirculation via app for peak-use windows only

Bottom line

The Rinnai RUR98iN Sensei+ is the right pick for homes with long pipe runs where instant hot water at distant fixtures is genuinely valuable. The integrated recirculation pump + Control-R 2.0 scheduling beats the aftermarket-pump alternative on convenience and price. For short-pipe-run homes, the non-recirc RU199iN or RU180iN saves the premium. Click through to Amazon for live pricing.