Product images: Amazon listings
Written from the listing's specs, not from our own use · How we rate
The Ranein 100,000 BTU Propane Indoor ticks most of the boxes we care about: a 4.3 GPM maximum flow and freeze protection. It suits one shower at a time and not much more, 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 | Propane |
| Stated mounting location | Indoor |
| Stated maximum flow | 4.3 GPM |
| Stated gas input | 100,000 BTU/h |
| Temperature range | 95 to 155 °F |
| Freeze protection | Stated in the listing |
| ASIN | B0C6PRDHF1 |
Full listing title: Ranein Propane Gas Tankless Water Heater, 4.3 GPM, 100,000 BTU, Indoor
| Fuel | PropaneFull listing title |
|---|---|
| Stated mounting location | IndoorFull listing title |
| Stated maximum flow | 4.3 GPMFull listing title |
| Stated gas input | 100,000 BTUFull listing title |
Rated from the listing's specs, no buyer reviews yet
What it's made for: one shower at a time and not much more.
Two gas tankless heaters on propane 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. Up north in winter, 42 °F water has to climb 63 °F to reach a 105 °F shower, and the flow drops with it. Ask for the flow chart and read that line. Our calculator counts a shower at 2 GPM, so on paper that's one shower at a time.
What it has going for it
Freeze protection. Stated in the listing. Useful in a garage, a crawl space or a cabin that sits empty in winter, as long as the unit keeps power.
95 to 155 °F. The setpoint range per the listing. Above 120 °F at the tap is scalding territory for kids, so most homes set it lower.
One at a time: that's what 4.3 GPM is for.
Two at once: not with this one. Look at the bigger units further down this page.
What the Ranein 100,000 BTU Propane Indoor listing names:
For the Ranein 100,000 BTU Propane Indoor, 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 $92.79 (price ÷ stated GPM, our arithmetic). That puts it around the middle of the 45 indoor gas tankless heaters we have a price and a stated flow for.
The heater is often the smaller half of the bill: the venting, a gas line that may need upsizing and a licensed installer's day come on top.
The button opens the exact listing (ASIN B0C6PRDHF1), 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 Rheem RTGH 8.4 GPM Natural Gas Indoor (7.3/10) states up to 8.4 GPM.
No easy route for a vent pipe? The Westinghouse 120,000 BTU Propane Outdoor (7.6/10) mounts on an outside wall, per its listing.
Want the high-efficiency kind? The Ranein Condensing Propane, 5.1 GPM (7.4/10) is a condensing unit, per its listing.
Our take
What we'd buy the Ranein 100,000 BTU Propane Indoor for is a 4.3 GPM maximum flow, with freeze protection as a bonus. No buyer reviews yet, so this Ranein indoor gas tankless heater has to win you over on paper. The catch with the Ranein: no stated temperature hold, while most picks here claim ±1 °F. We'd pick it if it will live in a garage, a cabin or another cold spot; otherwise, put it next to the Eccotemp SMARTHOME Natural Gas (6.8 GPM) first.
Old tank out, unit on the wall, vent through the wall or the roof. Plan the gas line for 100,000 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 clean the inlet filter. Our flushing and descaling guide has the checklist.
Before the Ranein 100,000 BTU Propane Indoor goes in your cart, check your gas line: 100,000 BTU/h is a lot of gas at once, so ask your plumber whether the existing line can feed it.
4.3 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.
Ask the plumber to check the gas line size and the meter against the heater's input, and to quote the vent route at the same visit. Our install cost guide shows what that usually adds.
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 100,000 BTU Propane Indoor stacks up against the closest alternative, the Eccotemp SMARTHOME Natural Gas (6.8 GPM).
| Criterion | Ranein 100,000 BTU Propane Indoor | Eccotemp SMARTHOME Natural Gas, 6.8 GPM |
|---|---|---|
| Our rating | 7.1/10 | 7.1/10 |
| Max flow | 4.3 GPM | 6.8 GPM |
| Gas input | 100,000 BTU/h | 140,000 BTU/h |
| Warranty | Not stated | 5 years (heat exchanger) |
| Buyer reviews | None captured | 3 · 2.7/5 |
Both score 7.1/10. The Eccotemp SMARTHOME Natural Gas (6.8 GPM) adds more flow (6.8 GPM) and a bigger burner (140,000 BTU/h).
We rate it 7.1/10 (good). The rating comes from its documented listing alone, as no customer-review record is captured yet.
The listing states a maximum flow of 4.3 GPM and a gas input of 100,000 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.
Yes, the listing says indoor mounting. That means a vent route to the outside, combustion air and a gas line sized for the unit, all as the maker and your local code require. A licensed plumber or gas fitter sorts that out.
Its listing states up to 4.3 GPM and freeze protection. 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: 4.3 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. Vent and gas line: ask the plumber to check the gas line size and the meter against the heater's input, and to quote the vent route at the same visit. Our install cost guide shows what that usually adds. 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.