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156 rated water heaters

Tankless water heater comparison: up to 3 models side by side

Down to two or three heaters? Line them up here. The best stated value on each row is highlighted, and a blank means the seller doesn't say, which is worth asking about before your plumber shows up.

Shareable link: the page address keeps your selection.

CriterionMIZUDO 199,000 BTU Natural Gas IndoorSee it on Amazon ↗Affiliate linkRanein 190,000 BTU Natural Gas IndoorSee it on Amazon ↗Affiliate linkRinnai RU199iN CondensingSee it on Amazon ↗Affiliate link
Rating9.2/10 · Excellent7.9/10 · Very good7.8/10 · Very good
Price$1,199†$699†See current price ↗
Buyer reviews307710 (shared)*388
FuelNatural gasNatural gasNatural gas
Stated maximum flow10.3 GPM8.5 GPM11 GPM
Stated input or power199,000 BTU/h190,000 BTU/hNot stated
Stated voltage120 VNot statedNot stated
MountingIndoorIndoorIndoor, condensing

Best stated value in the selection

† Prices as of Sep 30, 2026; they may have changed. The button always shows today's price.

* Shared: the same review pool appears on every variant of a listing family, so the count is not specific to one variant and is never marked as the best value. Ranein 190,000 BTU Natural Gas Indoor: 710 reviews · 4.2/5, shared by 2 variants (Ranein listing family).

Product images: Amazon listings

All rankings

vsBest Tankless Water Heaters in 2026#1: MIZUDO 199,000 BTU Natural Gas Indoor · 9.2/10vsBest Outdoor Propane Tankless Water Heaters in 2026#1: FOGATTI Outdoor Propane Tankless · 9.1/10vsBest Whole-House Electric Tankless Water Heaters in 2026#1: Rheem 18 kW Electric, 240V · 9.3/10vsBest High-Efficiency Condensing Tankless Water Heaters in 2026#1: Rinnai RU199iN Condensing · 9.1/10vsBest Gas Tankless Water Heaters in 2026#1: MIZUDO 199,000 BTU Natural Gas Indoor · 9.2/10vsBest Whole-House Tankless Water Heaters in 2026: Gas and Electric#1: MIZUDO 199,000 BTU Natural Gas Indoor · 9.2/10
Gas tankless water heaters →Electric tankless water heaters →Service kits, valves & parts →All product reviews →

Frequently asked questions

How does the comparison tool work?

Pick up to three heaters from the lists. The table shows the rating, the price we recorded, the buyer review count and the figures stated in each exact listing. The page address keeps your selection, so you can send the comparison to your plumber or to whoever shares the hot water (and the bill).

Where do the values come from?

From each exact listing and its public review record. We haven't installed or measured these units ourselves: flow, BTU/h input, kW and voltage are the seller's figures, and a stated maximum flow is not the flow you get at your winter temperature rise.

How current are the prices?

Each price is the one we recorded on the date shown under the table, and it may have changed since. Every button opens the exact listing on Amazon, where today's offer applies.