5 Best Tankless Water Heaters (2026) — Expert Reviews

Please note: Product availability and information are based on our research at time of writing and are subject to change. Always check Amazon for the latest details before purchasing.

Introduction

Tired of running out of hot water mid-shower — or paying to keep 50 gallons heated around the clock? A tankless water heater, also called an on-demand heater, fires up only when you turn on a hot tap and shuts off the moment you close it. No standby heat loss, no tank to maintain, and hot water that doesn’t run dry. The US Department of Energy estimates tankless units can be 24–34% more energy efficient than conventional storage heaters in the average home — and with a lifespan of 15–20 years, the long-term savings are substantial.

This 2026 refresh covers five tankless heaters that span the categories that actually decide your purchase: a whole-home electric unit for a house with no gas line, a whole-home propane gas unit for large homes and heavy simultaneous demand, a premium whole-home electric model built to a higher engineering standard, and two point-of-use electric heaters sized for a single fixture or a remote bathroom far from the main heater. Match the category to your home’s fuel supply, layout, and peak demand before you compare individual specs. If you are still deciding between tankless and a conventional tank, start with our tankless vs tank water heater comparison. If you need help with installation, PlumberArchive.com lists verified licensed plumbers across all 50 states.

Quick Comparison Table

The 5 Best Tankless Water Heaters — Full Reviews

1. Rheem 18kW 240V Tankless Electric Water Heater, Gray — Best Overall

🏆 BEST OVERALL WHOLE-HOME ELECTRIC

★★★★☆

The Rheem 18kW is a whole-home electric tankless heater for houses without a gas line. Running on 240V and drawing up to 18 kilowatts across three heating elements, it produces roughly 2 to 4 GPM of hot water depending on how cold your incoming supply is — enough for a shower and a sink together in a one-to-two-bathroom home, or a full two-to-three-bathroom home in warm southern climates. External digital controls set the outlet temperature in one-degree steps, and self-modulating power means it only draws the wattage the current flow actually needs.

It earns Best Overall on balance: the strongest ownership record of any unit in this guide, Rheem’s nationwide service and parts network, and a compact wall-mount body that fits a utility closet — all with no venting, no combustion air, and no gas work. It is still electric, so in northern states with sub-45°F groundwater you should plan on one bathroom at a time or move up to the propane model below.

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2. Ranein Propane Gas Tankless Water Heater, 8.5 GPM, 190,000 BTU, Indoor — Best Propane/Gas

🔥 BEST PROPANE/GAS WHOLE-HOME GAS

★★★★☆

The Ranein is the only combustion unit in this lineup: an indoor propane (LP) tankless heater rated at 8.5 GPM and 190,000 BTU. That output is in a different class from the electric models — it can supply four to six fixtures at once, which makes it the right choice for a large home, a household where several showers run together, or any property off the natural-gas grid that runs on a propane tank. It ships configured for indoor installation with the venting kit and a wired temperature controller included.

Because it burns fuel rather than pulling amps, the Ranein holds flow with cold winter groundwater far better than any electric unit here, where a 13-to-18kW heater would throttle back. The trade-offs are the ones every gas tankless carries: it needs sealed combustion venting to the outside, a correctly sized propane supply, and professional installation. It is not a DIY swap, and it is the most expensive unit here to put in.

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3. Stiebel Eltron Tempra 24 Trend Electric Tankless Water Heater — Best Premium

👷 BEST PREMIUM GERMAN ENGINEERING

★★★★★

The Tempra 24 Trend is a premium whole-home electric tankless heater built in Germany. At 24kW on 240V it sits at the top of the electric range, suiting two-to-three-bathroom homes across most US climates. Its signature feature is Advanced Flow Control: when simultaneous demand would otherwise exceed the unit’s capacity, it automatically trims the flow rate just enough to hold your set outlet temperature instead of sending a slug of cold water down the line.

The “Trend” is the streamlined version of Stiebel’s Tempra platform — the same core engineering and flow control with a simpler control interface at a lower price than the full Tempra Plus. Operation is silent, with no fan or combustion, and the build quality is what you are paying for: owners routinely run these 15 to 20 years. It does demand serious electrical service, though — a 24kW unit typically needs a dedicated 100A feed that older homes may not have.

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4. EcoSmart ECO 8 Tankless Water Heater — Best Point-of-Use

🎯 BEST POINT-OF-USE SINGLE FIXTURE

★★★★☆

The ECO 8 is a point-of-use electric heater, not a whole-home unit. At 8kW on 240V it is sized to serve one fixture or a small cluster close by — a remote bathroom, a wet bar, a workshop sink, or a guest suite that sits too far from the main water heater to get hot water quickly. Mounted within a few feet of the tap, it removes the long wait and the water wasted while the line warms up.

It uses the same EcoSmart self-modulating control as the brand’s larger units, so it draws power in proportion to the flow, and the compact body tucks into a vanity cabinet or onto a nearby wall. Expectations have to match the category: at 8kW it will comfortably run a single low-flow shower or a sink in a warm climate, but it is not built to feed a whole house or several fixtures at once.

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5. Eemax EEM24013 Electric Tankless Water Heater — Best Value Point-of-Use

💰 BEST VALUE POINT-OF-USE COMPACT

★★★★☆

The Eemax EEM24013 is the value pick for point-of-use hot water. It is a 13kW, 240V single-point electric heater in a very small enclosure, designed to sit right at the fixture it serves. Within its lane — one bathroom, a utility sink, an efficiency apartment — it delivers on-demand hot water with no tank and no standby loss, and it costs less than most competing single-point units.

At 13kW it has a little more headroom than the ECO 8, so in a moderate climate it can handle a shower plus a nearby sink at low flow, though it is still a point-of-use device rather than a house-wide solution. Construction is straightforward and serviceable, with an accessible heating element and a set-and-forget analog temperature dial rather than a digital readout. For adding one hot-water point on a budget, it is hard to beat.

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Tankless Water Heater Buying Guide

First, Pick a Category: Whole-Home vs Point-of-Use, Electric vs Propane

Before comparing specs, decide which of four categories fits your situation. A whole-home electric unit — the Rheem 18kW and the Stiebel Eltron Tempra 24 Trend — replaces a tank heater for the whole house and needs only a large 240V circuit: no gas line, no venting, no combustion air. It is the default for homes without gas, and for small-to-moderate homes in warm climates. A whole-home propane or gas unit — the Ranein — burns fuel for far higher output (8.5 GPM here), holds flow in cold-groundwater states, and suits large homes or heavy simultaneous demand, but it requires sealed venting, a sized gas line, and professional installation. A point-of-use electric heater — the EcoSmart ECO 8 and Eemax EEM24013 — is not a house-wide solution at all: it mounts at a single remote fixture to kill the long hot-water wait without re-plumbing. If you are weighing fuel type more broadly, our electric vs gas water heater guide covers the running-cost math.

How to Size a Tankless Water Heater (GPM Explained)

The most important specification is flow rate in GPM (gallons per minute). Each fixture draws a set amount of hot water: a standard shower uses roughly 2.0–2.5 GPM, a bathroom faucet around 0.5–1.0 GPM, and a dishwasher about 1.0–1.5 GPM. Add up the GPM of every fixture you are likely to run at the same time — that is your peak simultaneous demand, and your unit’s output has to meet it.
For a 1–2 bathroom home, an electric unit rated 13–18kW like the Rheem 18kW typically delivers 1.5–3.0 GPM of usable hot water in a moderate climate — enough for one shower and one faucet at once. For a large home where several showers run together, a high-output propane model like the Ranein (8.5 GPM) is the realistic choice; electric cannot match that flow. Point-of-use units like the ECO 8 and EEM24013 are sized per fixture, not per house. Climate matters throughout: colder groundwater in northern states needs more capacity to reach a comfortable temperature, so buyers in Minnesota, Wisconsin, or Maine should size up a tier compared with buyers in the South. For a full walkthrough with worked examples, see our water heater sizing guide.

Installation: DIY vs Professional

Electric tankless heaters are the more DIY-accessible option, but “accessible” is relative. A whole-home unit like the Rheem 18kW or the 24kW Stiebel Eltron Tempra 24 Trend draws enough current to need a dedicated high-amperage circuit and often a panel upgrade, so most homeowners bring in a licensed electrician and pull a permit. A single-element point-of-use unit like the EcoSmart ECO 8 is a more manageable project for an experienced DIYer. Propane and gas tankless heaters — the Ranein — should always be installed by a licensed plumber or gas technician: improper gas connections and venting are a serious safety hazard and void virtually every manufacturer’s warranty. If you need a qualified installer, search PlumberArchive.com — the US plumber directory with verified professionals across all 50 states.

Energy Savings and Long-Term Ownership

Traditional tank water heaters keep 40–80 gallons hot around the clock — including overnight and during work hours when no one is home. That standby heat loss accounts for 15–30% of a typical home’s water heating energy costs. Tankless heaters eliminate it: they heat on demand and shut off completely the moment you close the tap. According to US Department of Energy data, tankless heaters can be 24–34% more energy efficient than storage tank heaters in homes that use under 41 gallons of hot water per day.
The upfront cost of a tankless unit is higher than a replacement tank, but lower monthly running costs, a longer lifespan (15–20 years vs 8–12 for tank heaters), and zero standby waste mean most homeowners reach break-even within 5–8 years. One maintenance task protects that payback: in hard-water areas, descale the heat exchanger about once a year so efficiency and flow do not drift down. Our guide on how to flush and descale a tankless water heater walks through it.

Frequently Asked Questions

Q: How long do tankless water heaters last?

A well-maintained tankless water heater typically lasts 15–20 years — roughly twice the lifespan of a traditional storage tank heater, which averages 8–12 years. Electric and gas models both benefit from annual descaling in hard water areas, which keeps mineral buildup off the heat exchanger. A key advantage of tankless units is that most components are individually replaceable: if a control board or heating element fails, you swap the part rather than the whole unit, which extends useful life and lowers long-term ownership cost.

Q: Can I install a tankless water heater myself?

It depends on the type. Electric tankless heaters like the Rheem 18kW and the EcoSmart ECO series are designed with DIY installation in mind — if you are comfortable running a 240V circuit from your panel, the process is manageable, though a whole-home unit’s high amperage often still means an electrician and a permit. Point-of-use units are the simplest. Propane and gas tankless heaters like the Ranein should always be installed by a licensed plumber or gas technician — improper gas connections and venting are a genuine safety risk and will void the manufacturer’s warranty on virtually every model.

Q: What size tankless water heater do I need for a 3-bedroom home?

A typical 3-bedroom home has 1.5–2.5 bathrooms and peak simultaneous demand of around 3–5 GPM — one or two showers running alongside a faucet or dishwasher. For electric, look at units rated 18–24kW: the Rheem 18kW and Stiebel Eltron Tempra 24 Trend both cover this range well in moderate climates. For higher flow or colder climates, an 8+ GPM propane model like the Ranein is the better fit. Local climate is a key factor: in northern states with groundwater below 45°F, size up — you need significantly more heating power than in warm southern states where groundwater may reach 65°F.

Q: Do tankless water heaters work in cold climates?

Yes — but sizing becomes critical. In states like Minnesota, Wisconsin, or Maine, groundwater can fall to 35–40°F in winter, and a tankless heater then needs substantially more BTU (gas) or kW (electric) to raise that water to a comfortable 105–120°F. Propane models like the Ranein, with its 190,000 BTU output, handle cold climates confidently. Electric models in the 8–13kW range can struggle to hold flow when incoming water is very cold; step up to an 18–24kW electric unit like the Rheem 18kW or Stiebel Eltron Tempra 24 Trend, or move to propane if you live north of the Mason–Dixon line with multiple bathrooms to supply.

Conclusion — Which Tankless Water Heater Should You Buy?

For most homeowners replacing a whole-home tank heater, the Rheem 18kW 240V Tankless Electric Water Heater is the pick to beat — whole-home electric output with no gas line or venting, self-modulating power, the strongest ownership record in this guide, and Rheem’s nationwide service and parts network behind it. If your house has no gas supply and you are in a moderate or warm climate, this is the unit to buy.

• Best Overall: Rheem 18kW 240V Electric — whole-home electric, self-modulating, no gas line or venting
• Best Propane/Gas: Ranein 8.5 GPM Indoor — 190,000 BTU, true whole-home flow for large homes and cold climates
• Best Premium: Stiebel Eltron Tempra 24 Trend — German-built 24kW electric with Advanced Flow Control
• Best Point-of-Use: EcoSmart ECO 8 — 8kW electric for a single remote fixture
• Best Value Point-of-Use: Eemax EEM24013 — lowest-cost dedicated single-point hot water

Whichever model you choose, switching from a traditional storage tank to a tankless heater is one of the most impactful home efficiency upgrades you can make — lower monthly bills, unlimited hot water, and a unit built to last 15–20 years. If you need a licensed installer in your area, search PlumberArchive.com

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