Rinnai RE140iN
Amazon customer rating as of
Tankless Geek editorial score: 4.1/5
The Rinnai RE140iN is a compact, indoor, non-condensing natural-gas tankless heater rated at 140,000 BTU/h and a maximum 5.3 GPM. It's built for small-to-medium homes that want into the Rinnai ecosystem — the long heat-exchanger warranty, the nationwide service network, and the option to bolt on Wi-Fi and recirculation later — without paying condensing-unit prices.
As a non-condensing model it runs at 0.81 UEF, trading a few points of efficiency for a lower purchase price and simpler 3-in/5-in concentric venting. It modulates from 10,400 up to 140,000 BTU/h, activates at just 0.4 GPM, and holds a set temperature between 120 and 140 °F. At 38.5 lb and roughly the size of a small suitcase, it fits where a tank never could.
Key Features
Best Use Cases
Our Verdict
The RE140iN is the right call when you want a genuinely small, reliable gas tankless and your peak demand is modest — roughly two fixtures at once. Its 5.3 GPM ceiling is the honest limit: plenty for a couple showering back-to-back or a shower plus a sink, but not a whole-house workhorse for a large, cold-climate home. What you're really paying for is the platform — Rinnai's 15-year heat-exchanger warranty, a nationwide service network, quiet 54 dB operation, and the option to add Wi-Fi and recirculation later. Our take: the best-value entry into the Rinnai ecosystem for a small home — buy it for the warranty and reliability, and size up to the RE160i or RE199i if you have a big or cold-climate house.
Technical Specifications
| Max gas input | 140,000 BTU/h |
|---|---|
| Min gas input (modulation) | 10,400 BTU/h |
| Max flow rate | 5.3 GPM (20 L/min) |
| Activation flow | 0.4 GPM |
| Efficiency (UEF) | 0.81 · non-condensing |
| Temperature range | 120–140 °F |
| Dimensions (W×H×D) | 14.05 × 27.3 × 11.2 in |
| Weight | 38.5 lb (17.5 kg) |
| Sound level | 54 dB |
| Gas / water connections | ¾ in NPT |
| Gas supply pressure (NG) | 4.0–10.5 in w.c. |
| Venting | 3 in / 5 in concentric |
| Electrical | 120 V · 71 W run · 4 A max |
| High-altitude approved | up to 10,200 ft |
| Warranty | 15 yr heat exchanger · 5 yr parts · 1 yr labor |
Specifications verified against the linked source documents. See Sources below.
How much hot water you'll actually get
Usable flow drops as incoming water gets colder. Figures are calculated from rated output (140,000 BTU × 0.81 UEF) and labeled as such — not bench-tested by us.
| Temperature rise | Typical scenario | Usable flow |
|---|---|---|
| 35 °F | Warm climate (75 °F in → 110 °F) | 5.3 GPM |
| 45 °F | Mild climate (65 °F in → 110 °F) | 5 GPM |
| 60 °F | Cool climate (50 °F in → 110 °F) | 3.8 GPM |
| 70 °F | Cold climate (40 °F in → 110 °F) | 3.2 GPM |
Usable flow calculated from rated output (140,000 BTU × 0.81 UEF), capped at the unit's 5.3 GPM maximum and consistent with Rinnai's published flow curve.
Pros
Cons
Buy it if…
- Your home has 2–3 bathrooms and rarely runs 3+ hot taps at once
- You're in a mild-to-moderate climate (incoming water above ~50 °F)
- You want Rinnai's warranty and service coverage on a tight budget
- Indoor wall space is limited — it's the size of a small suitcase (38.5 lb)
Skip it if…
- You need 4+ simultaneous fixtures — step up to the RE160i (6.6 GPM) or RE199i (9.8 GPM)
- You're in a cold climate; at a 70 °F rise it delivers closer to 3.2 GPM
- You want maximum efficiency — a condensing unit (0.90+ UEF) will cut gas use
- You expected built-in recirculation — it's supported, but the pump is a separate add-on
Installation Requirements
Professional vs DIY
Gas and concentric venting make a licensed installer the safe route; professional install protects the 15-year heat-exchanger warranty.
Gas and electrical work should be done by a licensed professional, and most installs require a permit and must meet local building codes — DIY work can void the manufacturer warranty. Always confirm the unit's own manual for exact clearances, venting, and sizing.
What owners report
Themes summarized from retailer customer feedback (4.4/5 Amazon customer rating, 73 ratings, as of 2026-09-13). These are owner opinions, not our own bench testing.
Endless, consistent-temperature hot water once it reaches the tap; owners note it heats water well and is easy to adjust.
Compact, suitcase-sized footprint and a straightforward indoor install for a gas unit.
Reliable in the first year of ownership, with quiet operation.
Wait time for hot water to reach distant fixtures — the classic tankless lag, which an add-on recirculation pump addresses.
Some installs need extra components (correct gas-line sizing, venting), so budget for professional installation.
Rinnai RE140iN FAQ
Can the RE140iN run a whole house?+
It depends on your climate and how many fixtures run at once. At 5.3 GPM max it handles two simultaneous fixtures in a warm climate, but in cold climates its usable flow drops to roughly 3.2 GPM — enough for one shower plus a sink. For a large or cold-climate home, step up to the RE160i or RE199i.
Does it have Wi-Fi and a recirculation pump?+
It's capable of both, but neither is built in. Wi-Fi (remote monitoring and recirculation control) requires Rinnai's Control-R module, and recirculation requires an external pump — both sold separately. Out of the box it's run by its integrated front-panel controller.
Is it condensing or non-condensing?+
Non-condensing, at 0.81 UEF. That means a lower purchase price and simpler 3-in/5-in concentric venting, but slightly higher gas use than a condensing unit (typically 0.90+ UEF). It's a deliberate value trade-off.
What's the warranty?+
15 years on the heat exchanger (or 12,000 operating hours, whichever comes first), 5 years on all other parts, and 1 year of reasonable labor — one of the longest coverages in its price class.
Can it be installed at high altitude or in a mobile home?+
Yes. It's approved up to 10,200 ft and is mobile-home certified. It also meets Ultra-Low-NOx emissions requirements, so it's approved in strict air-quality districts.
Product sources
Specifications verified 2026-09-13. Manufacturer documents are treated as the primary source for model specifications. Retailer pages are used only for customer ratings and owner-feedback themes.
- Rinnai — RE140iN official product page (accessed 2026-09-13)
- Rinnai — REi-SP Non-Condensing Residential Indoor Spec Sheet (RE199i/180i/160i/140i) (accessed 2026-09-13)
Price range from leading retailers
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