Heater choices

3 Best Tankless Water Heaters for Different Homes in 2026

As an Amazon Associate, this website earns from qualifying purchases.

Bright bathroom with a glass shower and folded towels

The short answer

Start with supported winter flow. Rinnai RX199iN suits gas projects; Tempra 29 Plus adds flow control; Rheem RTEX-24 is an electric alternative.

Sections7

Our top 3 picks

  1. 1Flexible gas layoutRinnai RX199iNRinnai RX199iNRinnai RX199iN

    Gas-equipped homes comparing a condensing installation indoors or outdoors.

    • Natural gas or propane configuration
    • Condensing gas heating
    • Outdoor installation requires the RX-OVC accessory

    Keep in mind: Condensate disposal and the exact vent or outdoor kit remain part of the project.

    View on AmazonRead our analysis
  2. 2Flow controlStiebel Eltron Tempra 29 PlusStiebel Eltron Tempra 29 PlusStiebel Eltron Tempra 29 Plus

    A home with enough electrical capacity that values a steady outlet temperature.

    • Electric heating: 28.8 kW at 240 V
    • Output falls to 21.6 kW at 208 V
    • Advanced Flow Control can reduce water flow

    Keep in mind: Holding temperature can mean a slower flow when demand exceeds output.

    View on AmazonRead our analysis
  3. 3Electric alternativeRheem RTEX-24Rheem RTEX-24Rheem RTEX-24

    A home whose winter water load and electrical supply fit the model.

    • Electric heating: 24 kW at 240 V
    • Digital temperature control
    • Heating elements replace a gas burner

    Keep in mind: The maximum stated flow is not a cold-water performance guarantee.

    View on AmazonRead our analysis

The best tankless water heater fits the winter water load. The home must also be able to supply it. These three picks serve different needs. No one model suits every home. Check flow at the required temperature rise before choosing a size.

#1. Rinnai RX199iN: a gas option

Rinnai RX199iN

Rinnai RX199iN Rinnai RX199iN

Our verdict:

Flexible gas layout

Gas-equipped homes comparing a condensing installation indoors or outdoors.

  • Natural gas or propane configuration
  • Condensing gas heating
  • Outdoor installation requires the RX-OVC accessory

Keep in mind: Condensate disposal and the exact vent or outdoor kit remain part of the project.

View on Amazon

The RX199iN is a condensing gas model. It can be set up for natural gas or propane. Outdoor use needs the RX-OVC kit. Indoor use needs the right vent route and a condensate drain. Check the full package in each quote; the heater alone is not the full job.

Choose this route when gas supply and the proposed location make sense. Check the model's flow at your winter conditions. A maximum GPM figure does not show what every home will get. Use the maker's table and the actual water demand, including the taps that run together.

#2. Stiebel Eltron Tempra 29 Plus: electric flow control

Stiebel Eltron Tempra 29 Plus

Stiebel Eltron Tempra 29 Plus Stiebel Eltron Tempra 29 Plus

Our verdict:

Flow control

Households with sufficient electrical capacity that value a steady outlet temperature.

  • Electric heating: 28.8 kW at 240 V
  • Output falls to 21.6 kW at 208 V
  • Advanced Flow Control can reduce water flow

Keep in mind: Holding temperature can mean a slower flow when demand exceeds output.

View on Amazon

The Tempra 29 Plus adds Advanced Flow Control to electric heat. It can reduce flow to hold the set temperature when demand is too high. That may suit a home that accepts a slower shower when taps run together. It cannot add more heat than the unit can produce.

Read the Tempra Plus review for the voltage and supply checks. A small case does not prove the home can power it. Spare breaker spaces do not prove that either. Confirm the work needed before you order.

#3. Rheem RTEX-24: an electric alternative

Rheem RTEX-24

Rheem RTEX-24 Rheem RTEX-24

Our verdict:

Electric alternative

A home with a supported electrical supply and an inlet temperature that suits the required flow.

  • Electric heating: 24 kW at 240 V
  • Digital temperature control
  • Heating elements replace a gas burner

Keep in mind: The maximum stated flow is not a cold-water performance guarantee.

View on Amazon

The RTEX-24 has digital temperature control and 24 kW of heating at 240 V. Use the same inlet water and outlet target for each pick. Warmer water can make a headline flow look much higher. It does not show that the unit will do better in winter.

Our electric heater comparison explains the choice between these electric ranges. Keep the full supply scope in view. Reusing an old tank heater's circuit should never be assumed from the fuel type alone.

Factors to consider: best tankless water heater

Measure the hot-water flow needed at the same time. Use the coldest supported inlet condition and compare the required rise with the exact model's table. Room count does not establish flow. A household that keeps showers apart can have a very different peak from one that runs them together.

Then check the site. Gas models need the right fuel supply and a safe vent or outdoor layout. Electric models need enough power at the right voltage. Both need service access and a water-quality plan.

Compare the full work scope. Keep unknown work visible in the quote. The cost of the unit alone does not settle the cost of the job.

How We Picked

We used current US maker documents and exact product catalog checks. We have not installed or tested these heaters. The choices focus on supply fit and useful controls. We check flow at the needed rise rather than compare headline numbers. No customer score proves that a unit can meet your winter demand.

More in this guide

Verdict: best tankless water heater for the project

The best tankless water heater meets both the water load and the installation limits. Start with the sizing calculator, then compare the exact model documents and the full work scope. A pump or a different control cannot make up for too little heating output. Choose only when the two checks agree.

Sources: Rinnai RX199iN, Stiebel Eltron Tempra Plus, and Rheem tankless range. Checked October 16, 2026.

Our picks in this topic

Quick answers

What is the downside to a tankless water heater?

The main trade-off is that the water load and the home's supply must fit at the same time. Tankless can need substantial gas or electrical work, and cold inlet water reduces supported flow. Compare the complete project before buying.

What is the top rated electric tankless water heater?

This comparison does not rank customer stars. For these electric picks, compare voltage-specific output, the winter flow table and control behavior. A maximum flow figure without its temperature rise does not identify the right heater for the home.

Is Rheem or Rinnai better?

Compare exact models first. The Rinnai gas pick and Rheem electric pick need different supplies. Match the winter water load, then compare the installation scope and controls. A brand name does not make two different heating systems equivalent.