Product images: Amazon listings
Written from the listing's specs, not from our own use · How we rate
If you're after an 8.5 GPM maximum flow, the Ranein 190,000 BTU Natural Gas Outdoor delivers, with outdoor mounting that skips the flue on top. It suits replacing a 40-gallon tank in a mid-size home, and its sibling listing, the Ranein 190,000 BTU Natural Gas Indoor, holds #2 in our indoor natural gas tankless water heater ranking.
These are sold as variants of one listing family. Each variant has its own page.
| Brand | Ranein |
|---|---|
| Category | Gas tankless water heaters |
| Fuel | Natural gas |
| Stated mounting location | Outdoor |
| Stated maximum flow | 8.5 GPM |
| Stated gas input | 190,000 BTU/h |
| Freeze protection | Stated in the listing |
| ASIN | B0GJFPX2X3 |
Full listing title: Ranein Natural Gas Tankless Water Heater, 8.5 GPM, 190,000 BTU, Outdoor
| Fuel | Natural GasFull listing title |
|---|---|
| Stated mounting location | OutdoorFull listing title |
| Stated maximum flow | 8.5 GPMFull listing title |
| Stated gas input | 190,000 BTUFull listing title |
Rated from the listing's specs, no buyer reviews yet
What it's made for: replacing a 40-gallon tank in a mid-size home.
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. At 2 GPM a shower (our calculator's figure), the headline means 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. The listing states freeze protection, which typically needs power at the wall to work.
Mild winters: hang it outside and you skip the vent run through the rim joist and the combustion-air questions indoors.
Hard freezes: the listing states freeze protection. It only works while the unit has power, so an outage on a frozen night is the risk to plan for; drain it if the power stays off.
The seller states, word for word, in the Ranein 190,000 BTU Natural Gas Outdoor listing:
Uses standard 3/4" NPT water inlet fittings and gas inlets for quick installation.
It is suitable for 4-6 outlet points.
The seller's claims, quoted as written; we haven't measured any of it. The flow at your winter rise is in the maker's chart, not in the bullet points.
What the Ranein 190,000 BTU Natural Gas Outdoor listing names:
For the Ranein 190,000 BTU Natural Gas Outdoor, the installation manual settles the venting, the gas line and the clearances.
At the price on Sep 30, 2026, each GPM of stated maximum flow works out at about $82.24 (price ÷ stated GPM, our arithmetic). That puts it in the cheaper 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 B0GJFPX2X3), where today's price, stock and seller apply. Sizes and variants of the same family often sit at different prices.
Hard freezes where you live? The Rheem RTGH 8.4 GPM Natural Gas Indoor (7.3/10) is an indoor unit, out of the frost.
Want the high-efficiency kind? The A. O. Smith 10 GPM Natural Gas Outdoor (8.0/10) is a condensing unit, per its listing.
On propane, not natural gas? The APUS 190,000 BTU Propane Outdoor (6.9/10) runs on propane.
Our take
Our favourite thing about the Ranein 190,000 BTU Natural Gas Outdoor is an 8.5 GPM maximum flow, closely followed by outdoor mounting that skips the flue. No buyer reviews yet, so the Ranein 190,000 BTU Natural Gas Outdoor has to win you over on paper. The catch with this Ranein outdoor tankless heater: no stated temperature hold, while most picks here claim ±1 °F. We'd pick the Ranein if you run one shower and the kitchen tap at once, rarely more; otherwise, put it next to the APUS 190,000 BTU Propane Outdoor first.
It goes on an outside wall, with gas, water and power run to it. Plan the gas line for 190,000 BTU/h; 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 Ranein 190,000 BTU Natural Gas Outdoor ships, check your gas line: 190,000 BTU/h is a lot of gas at once, so ask your plumber whether the existing line can feed it.
8.5 GPM is the headline. In a northern January the water comes in near 42 °F, so a 105 °F shower needs a 63 °F rise and the real flow drops. Our flow-rate calculator runs the numbers for your house.
Pick a wall away from windows and doors, with power for the controls and the freeze protection the listing mentions. Our indoor vs outdoor guide compares the two installs.
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 Ranein 190,000 BTU Natural Gas Outdoor stacks up against the closest alternative, the APUS 190,000 BTU Propane Outdoor.
| Criterion | Ranein 190,000 BTU Natural Gas Outdoor | APUS 190,000 BTU Propane Outdoor |
|---|---|---|
| Our rating | 6.9/10 | 6.9/10 |
| Max flow | 8.5 GPM | 8.1 GPM |
| Efficiency | Not stated | 0.81 UEF |
| Temperature hold | Not stated | ±1 °F stated |
| Warranty | Not stated | 2 years |
| Buyer reviews | None captured | 102 · 4.0/5 |
Both score 6.9/10. The APUS 190,000 BTU Propane Outdoor adds a stated 0.81 UEF and a stated ±1 °F hold, while the Ranein 190,000 BTU Natural Gas Outdoor brings more flow (8.5 GPM).
We rate it 6.9/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a maximum flow of 8.5 GPM and a gas input of 190,000 BTU/h. 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 8.5 GPM and outdoor mounting that skips the flue. 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: 8.5 GPM is the headline. In a northern January the water comes in near 42 °F, so a 105 °F shower needs a 63 °F rise and the real flow drops. Our flow-rate calculator runs the numbers for your house. The outside wall: pick a wall away from windows and doors, with power for the controls and the freeze protection the listing mentions. Our indoor vs outdoor guide compares the two installs. The warranty terms: 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.