Product images: Amazon listings
Written from the listing's specs, not from our own use · How we rate
On paper, the Rinnai RE180eN Non-Condensing gets the important things right: a 6.9 GPM maximum flow, outdoor mounting that skips the flue and a 15-year heat exchanger warranty. It is a good match for a two-bathroom house with one shower running at a time, at 7.0/10 on its documented specs.
These are sold as variants of one listing family. Each variant has its own page.
| Brand | Rinnai |
|---|---|
| Category | Gas tankless water heaters |
| Fuel | Natural gas |
| Stated mounting location | Outdoor |
| Stated maximum flow | 6.9 GPM |
| Wi-Fi | With an optional module |
| Stated warranty | 15 years on the heat exchanger |
| ASIN | B0B57P29PY |
Full listing title: Rinnai RE180eN Non-Condensing Natural Gas Tankless Water Heater
| Fuel | Natural GasFull listing title |
|---|---|
| Stated mounting location | RE180eNFull listing title (Rinnai model suffix: i = indoor, e = exterior) |
| Stated maximum flow | up to 6.9 GPMListing text |
Rated from the listing's specs, no buyer reviews yet
What it's made for: a two-bathroom house with one shower running at a time.
Two gas tankless heaters on natural gas too, with about the same flow, closest to it on our rating, each with a dated price.
That's the maximum flow the listing states, and headline flows are usually quoted at a mild temperature rise. With January water coming in at 42 °F and a 105 °F shower, the rise is 63 °F and the real flow is lower; the maker's flow chart has that number. Our calculator counts a shower at 2 GPM, so on paper that's two showers and a kitchen tap, less when the water comes in cold.
What it has going for it
Mounts outside. No vent pipe through the roof or the rim joist: it hangs on an outside wall and breathes on its own. In a cold climate, ask what keeps it from freezing.
15-year warranty. 15 years on the heat exchanger, per the listing. Read what it needs from you: many makers ask for a licensed install and regular flushing to keep it valid.
Mild winters: the Rinnai RE180eN Non-Condensing goes on an outside wall, which saves the vent pipe and keeps the closet free.
Hard freezes: the listing names no freeze protection, so ask the seller what keeps it from bursting before it goes on a north wall.
What the Rinnai RE180eN Non-Condensing listing names:
Warranty & support: 15-year warranty on the heat exchanger, as stated in the listing.
That is the maker's promise, not ours. Keep the invoice, register the Rinnai RE180eN Non-Condensing if the maker asks, and read the install conditions: many tankless warranties need a licensed install and regular flushing.
The installation manual has the last word on venting, gas line and clearances; your installer reads it before you order.
At the price on Sep 30, 2026, each GPM of stated maximum flow works out at about $158.14 (price ÷ stated GPM, our arithmetic). That puts it in the pricier third of the 32 outdoor tankless heaters we have a price and a stated flow for.
Outside mounting saves the vent pipe; the gas line, the water lines and a weatherproof outlet are still a separate bill.
The button opens the exact listing (ASIN B0B57P29PY), where today's price, stock and seller apply. Sizes and variants of the same family often sit at different prices.
Two showers and the dishwasher at once? The A. O. Smith 10 GPM Natural Gas Outdoor (8.0/10) states up to 10 GPM.
Hard freezes where you live? The Eccotemp SMARTHOME Natural Gas, 6.8 GPM (7.1/10) is an indoor unit, out of the frost.
The far bathroom takes ages to run hot? The Rinnai REP199eN Smart-Circ (7.3/10) has built-in recirculation, per its listing.
Our take
Our favourite thing about the Rinnai RE180eN Non-Condensing is a 6.9 GPM maximum flow, closely followed by outdoor mounting that skips the flue. No buyer reviews yet, so the Rinnai RE180eN Non-Condensing has to win you over on paper. The catch with the Rinnai RE180eN Non-Condensing: no stated temperature hold, while most picks here claim ±1 °F. We'd pick it if you run one shower and the kitchen tap at once, rarely more; otherwise, put it next to the VELPAX 20L Natural Gas Outdoor first.
It goes on an outside wall, with gas, water and power run to it. a licensed pro handles it, and often a permit.
Hot water arrives after the cold already in the pipes, then stays. A trickle from a bathroom tap may not light the burner; open it a bit more.
January water comes in colder, so the same unit gives fewer GPM. Stagger the showers if you sized it tight.
Flush the heat exchanger with a pump and a descaler (the service valves make it an hour's job), and clear leaves and wasp nests from the cabinet vents. Our flushing and descaling guide has the checklist.
Before the Rinnai RE180eN Non-Condensing ships, check your winter flow: 6.9 GPM is a best case, so run your January numbers in our calculator first.
Count the fixtures that run together on a busy morning (our calculator uses 2 GPM a shower, 1.5 for the kitchen), then compare with the maker's chart. Our sizing guide shows how.
Pick a wall away from windows and doors, with power for the controls. Our indoor vs outdoor guide compares the two installs.
15 years are stated on the heat exchanger. Read what it requires: a licensed install, the gas type and regular flushing are the usual conditions.
Hard water scales the heat exchanger. Service valves on the water lines turn the yearly flush into an hour with a bucket and a pump; our flushing and descaling guide shows the routine.
How the Rinnai RE180eN Non-Condensing stacks up against the closest alternative, the VELPAX 20L Natural Gas Outdoor.
| Criterion | Rinnai RE180eN Non-Condensing | VELPAX 20L Natural Gas Outdoor |
|---|---|---|
| Our rating | 7.0/10 | 7.0/10 |
| Max flow | 6.9 GPM | 5.26 GPM |
| Gas input | Not stated | 120,000 BTU/h |
| Temperature hold | Not stated | ±1 °F stated |
| Warranty | 15 years (heat exchanger) | Not stated |
Both score 7.0/10. The VELPAX 20L Natural Gas Outdoor adds a bigger burner (120,000 BTU/h) and a stated ±1 °F hold, while the Rinnai RE180eN Non-Condensing brings more flow (6.9 GPM) and a longer stated warranty (15 years).
We rate it 7.0/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a maximum flow of 6.9 GPM. The headline flow is a mild-weather number: with cold winter water coming in, the same unit gives you less. Read the maker's flow chart at your winter rise, or let our flow-rate calculator do the sums.
The listing says outdoor mounting. It only goes inside if the maker lists that exact model for indoor use, with the venting it specifies; a licensed gas installer confirms the spot under your local code.
Its listing states up to 6.9 GPM, outdoor mounting that skips the flue and a 15-year heat exchanger warranty. These are the seller's figures, not our measurements: how steady the temperature is in your shower and how it copes with your winter water can't be read from a listing.
Your winter flow: count the fixtures that run together on a busy morning (our calculator uses 2 GPM a shower, 1.5 for the kitchen), then compare with the maker's chart. Our sizing guide shows how. The outside wall: pick a wall away from windows and doors, with power for the controls. Our indoor vs outdoor guide compares the two installs. The warranty terms: 15 years are stated on the heat exchanger. Read what it requires: a licensed install, the gas type and regular flushing are the usual conditions. Flushing: hard water scales the heat exchanger. Service valves on the water lines turn the yearly flush into an hour with a bucket and a pump; our flushing and descaling guide shows the routine.
We link to the exact listing on Amazon, where today's price, stock and seller apply. It is an affiliate link, and it has no effect on the rating.
No, we haven't used it ourselves. Everything on this page comes from its listing, read line by line and weighed with our published formula.