The 5 Best Tankless Water Heaters, Reviewed by BHG

Hot water is one of those everyday luxuries we only truly appreciate when it disappears mid-shampoo. A traditional tank water heater stores gallons of hot water and keeps reheating it all day, whether you need it or not. A tankless water heater works differently: it heats water on demand, which can save space, reduce standby energy loss, and help your household avoid the dreaded “who used all the hot water?” courtroom drama.

Based on Better Homes & Gardens’ reviewed picks, along with current buying guidance from energy agencies, manufacturers, and home-improvement experts, the best tankless water heater is not simply the biggest or most expensive model. The right choice depends on your home’s fuel source, incoming water temperature, electrical capacity, bathroom count, flow-rate needs, installation location, and budget. In other words, this is one appliance where “just grab the popular one” can lead to cold showers and spicy family feedback.

Below is an in-depth, practical review of five standout tankless water heaters: the Stiebel Eltron Tempra 36 Plus, Rinnai RXP160iN, Ranein Propane Tankless Water Heater, Camplux Portable Propane Tankless Water Heater, and Rinnai RX199iN. Each one serves a different type of home, from small spaces and off-grid setups to larger households with multiple bathrooms.

Why Choose a Tankless Water Heater?

A tankless water heater, also called an on-demand water heater, heats water only when a faucet, shower, dishwasher, or washing machine calls for it. Instead of maintaining a large tank of hot water around the clock, the unit activates when water flows through it. Gas models use burners and heat exchangers, while electric models use high-powered heating elements.

The biggest benefits are space savings, continuous hot water, and improved energy efficiency. Tankless units are usually wall-mounted and much smaller than bulky storage tanks, making them attractive for utility closets, garages, apartments, additions, cabins, and homes where every square foot is already spoken for by shoes, holiday decorations, or mystery boxes labeled “misc.”

That said, tankless water heaters are not magic boxes. They must be sized correctly. Flow rate, measured in gallons per minute (GPM), tells you how much hot water a unit can deliver under ideal conditions. Gas units often provide higher GPM and are better for whole-house use. Electric units can work beautifully in smaller homes, warm climates, or point-of-use situations, but large electric models may require serious electrical capacity.

Quick Comparison: The 5 Best Tankless Water Heaters

1. Stiebel Eltron Tempra 36 Plus: Best Electric Tankless Water Heater

The Stiebel Eltron Tempra 36 Plus is a strong pick for homeowners who want an electric tankless water heater with precise temperature control and a clean, compact design. It is especially appealing in homes where gas is not available or where venting a gas appliance would be difficult or expensive.

Its standout feature is advanced flow control. When hot water demand gets too high, the unit can slightly reduce flow to help maintain a steady output temperature. That is better than letting the water suddenly turn cold while someone is covered in conditioner and regret. The Tempra 36 Plus also uses self-modulating technology, meaning it adjusts power use according to demand instead of blasting full power every time.

Why It Stands Out

This model is compact, quiet, and does not require gas venting. It can be installed indoors and is well suited for homes with adequate electrical service. The digital controls are simple, and the steady-temperature design is a major comfort feature. For households that want an electric whole-house tankless system, this is one of the most polished options.

What to Consider

The electrical requirements are not casual. A 36-kW electric tankless water heater can require substantial amperage, and many homes may need an electrical panel evaluation or upgrade. Before buying, consult a licensed electrician. This is not the appliance to “figure out as you go,” unless your hobby is tripping breakers at Olympic speed.

Best for: Smaller to medium-size homes, warm climates, electric-only properties, and homeowners who prioritize steady temperature control.

2. Rinnai RXP160iN: Best Natural Gas Tankless Water Heater

The Rinnai RXP160iN is a premium natural gas tankless water heater designed for households that need reliable hot water across multiple fixtures. It offers strong output, high efficiency, and the flexibility of indoor or outdoor installation with the right accessories.

With a maximum input of 160,000 BTU and a high flow-rate rating, this unit can support busy homes where showers, sinks, and appliances may overlap. It is also part of Rinnai’s condensing lineup, which helps capture more heat from exhaust gases and improves overall efficiency compared with many non-condensing gas models.

Why It Stands Out

The RXP160iN combines strong household capacity with modern efficiency. It is a good match for families, multiple-bathroom homes, and homeowners who want the convenience of continuous hot water without moving up to the largest, most expensive model in the category.

It also offers smart compatibility, though some wireless features may require a separate module. That means you can potentially monitor or control the system remotely, depending on setup. For tech-friendly homeowners, app control is a nice perk; for everyone else, it is still comforting to know the water heater has more brains than the average toaster.

What to Consider

Gas tankless installation can be more complex than replacing a standard tank. Venting, gas line sizing, condensate drainage, combustion air, and local code requirements all matter. A professional installer should confirm that the unit is properly sized for your home and climate.

Best for: Families, larger homes, natural gas households, and homeowners who want a balance of power and efficiency.

3. Ranein Propane Tankless Water Heater: Best Propane Option

The Ranein Propane Tankless Water Heater is a compact indoor propane model that works well for homes without natural gas service. It is designed to deliver on-demand hot water for smaller households, cabins, accessory dwelling units, and spaces where propane is already part of the utility setup.

With a flow rate around 3.6 GPM and heating power around 80,000 BTU, this model is not intended to run a luxury shower, dishwasher, and laundry cycle all at once. However, it can be a very practical solution for modest hot water demand. Think efficient and focused, not “spa day for six people.”

Why It Stands Out

The Ranein is appealing because it provides indoor propane functionality in a compact package. It also includes multiple temperature modes, which can help maintain more stable water for different uses such as washing dishes or showering.

For rural homes, small houses, workshops, and cabins, propane can be a dependable option. A propane tankless water heater may also be useful when extending natural gas lines would be too expensive or simply unavailable.

What to Consider

This is a non-condensing model, so venting and professional installation are important. Indoor gas appliances need proper exhaust handling and safe setup. Also, propane supply must be sized correctly. If the fuel delivery system cannot keep up, the heater cannot perform as advertised.

Best for: Smaller homes, cabins, propane-ready properties, and homeowners who need indoor on-demand hot water without natural gas.

4. Camplux Portable Propane Tankless Water Heater: Best Budget Pick

The Camplux Portable Propane Tankless Water Heater is the budget-friendly wildcard of the group. It is not designed to replace a full home water heater, but it shines as a portable hot-water solution for camping, outdoor showers, cabins, pet washing, tailgating, and off-grid use.

With about 1.32 GPM and 34,000 BTU of heating output, the Camplux is best for light-duty use. It can provide a simple hot shower outdoors or warm water where plumbing is limited. It is small, lightweight, and easier to move than whole-house units. In appliance terms, this is less “main character mansion upgrade” and more “very helpful friend with a folding chair.”

Why It Stands Out

Affordability and portability are the main draws. The unit activates when water flows, runs on propane, and typically uses batteries for ignition. It often comes with accessories such as a shower head and gas regulator, depending on the package.

For outdoor applications, it can be surprisingly useful. Gardeners, campers, pet owners, and DIYers may find it more practical than dragging buckets of warm water around like they are auditioning for a pioneer documentary.

What to Consider

The low flow rate means it is not suitable as a whole-house water heater. It also requires careful winter storage and draining, because freezing water can damage internal components. Most importantly, portable propane water heaters must be used according to the manufacturer’s safety instructions, especially regarding outdoor installation and ventilation.

Best for: Outdoor showers, camping, cabins, off-grid projects, pet washing, and budget-conscious buyers who do not need whole-house performance.

5. Rinnai RX199iN: Best Upgrade Tankless Water Heater

The Rinnai RX199iN is the powerhouse pick for homeowners who want high flow, high efficiency, and premium performance. With output up to 199,000 BTU and flow rates up to about 11.1 GPM under ideal conditions, this model is built for homes with more demanding hot water needs.

This is the type of unit to consider if you have multiple bathrooms, frequent overlapping use, or a household that treats showers like scheduled conferences. It is also a condensing model, which improves energy performance by using heat that would otherwise be lost through exhaust.

Why It Stands Out

The RX199iN offers the strongest performance in this group. Its high flow rate makes it suitable for running multiple fixtures at once, and its high UEF rating places it among efficient gas tankless options. It can also be configured for indoor or outdoor installation, depending on the setup and accessories.

For homeowners replacing a large tank water heater or planning a major remodel, this unit can be a compelling upgrade. It is especially attractive when hot water demand is high but available space is limited.

What to Consider

The RX199iN costs more upfront and may require a properly sized gas line, condensate drain, and professional venting. The installation details can significantly affect total cost. Before buying, have a licensed plumber evaluate gas supply, water hardness, vent routing, and local code requirements.

Best for: Large homes, high-demand households, remodels, premium installations, and buyers who want maximum tankless performance.

How to Choose the Best Tankless Water Heater for Your Home

1. Start With Fuel Type

Your existing utilities should guide your decision. If your home has natural gas, a gas tankless water heater may offer the best whole-house performance. If your home is all-electric, an electric model may be easier to place but harder on your electrical panel. If you live in a rural area, propane may be the most practical choice.

2. Calculate Flow Rate

Flow rate is one of the most important numbers to understand. A shower may use around 2 to 2.5 GPM, while faucets and appliances add more demand. If two showers and a kitchen sink may run at the same time, you need a unit that can handle that combined load. Also remember that colder incoming water reduces performance because the heater must work harder to raise the water temperature.

3. Consider Climate

A tankless heater installed in Florida does not face the same incoming water temperature as one installed in Minnesota. Colder groundwater requires more energy to reach the same comfortable shower temperature. That means a model advertised at a certain GPM may deliver less in colder regions.

4. Think About Installation Costs

Tankless water heaters can save space and energy, but installation is often more expensive than a standard tank replacement. Gas models may need new venting, gas line upgrades, and condensate drainage. Electric models may require new breakers, wiring, or panel upgrades. Always budget for professional labor, not just the appliance box.

5. Do Not Ignore Maintenance

Tankless systems need regular maintenance, especially in hard-water areas. Flushing or descaling helps prevent mineral buildup inside the heat exchanger. Skipping maintenance can reduce efficiency, damage components, and shorten the unit’s lifespan. In plain English: your tankless heater may be compact, but it still has feelings.

Tankless Water Heater Experiences: What Homeowners Often Learn After Installation

One of the most common experiences homeowners report after switching to a tankless water heater is surprisenot always at the hot water, but at how different the system feels from a tank. With a tank, hot water is stored and ready until it runs out. With a tankless unit, hot water is produced as needed, which means there may be a short delay before the heater activates and hot water reaches the faucet. This delay is normal, especially if the bathroom is far from the heater.

Another real-world lesson is that “endless hot water” does not mean “unlimited hot water at every fixture forever.” A correctly sized tankless unit can provide continuous hot water within its flow capacity. If the unit can comfortably support two showers and a sink, it should do that well. But if someone adds a washing machine, dishwasher, and third shower, the heater may reduce output or deliver cooler water. The best experience comes from matching the unit to actual household habits, not wishful thinking.

Homeowners also notice that installation quality matters enormously. A great tankless water heater can perform poorly if the gas line is undersized, the venting is wrong, the electrical service is inadequate, or the water hardness is ignored. This is why professional installation is strongly recommended. Tankless systems are compact, but they are not simple plug-and-play gadgets. They are serious appliances connected to water, fuel, electricity, and building codesbasically the home-improvement version of a group project where every member must do their job.

Maintenance is another experience that surprises some buyers. A tank water heater may sit quietly for years until it complains dramatically. Tankless units often need more routine attention, especially annual flushing in areas with hard water. Installing a service valve kit and using a water softener or scale-reduction system can make ownership easier. The reward is better performance, longer equipment life, and fewer emergency calls that begin with, “So, funny story, nobody can shower.”

Comfort expectations also vary by model. Electric units like the Stiebel Eltron Tempra 36 Plus can be smooth and quiet, but they may need major electrical capacity. Gas units like the Rinnai RXP160iN and RX199iN can support higher demand, but they require proper gas and venting infrastructure. Portable units like the Camplux are wonderfully convenient outdoors, but they should never be mistaken for whole-house systems. Propane units like the Ranein can be excellent in the right setting, especially where natural gas is unavailable.

The happiest tankless water heater owners usually do three things before buying: they measure their hot water needs, check installation requirements, and choose a reputable model with accessible parts and support. When those pieces line up, tankless water heating can feel like a smart, space-saving upgrade. When they do not, the experience can feel like owning a very expensive metal box with commitment issues.

Final Verdict

The best tankless water heater depends on your home, not just the product label. For electric homes, the Stiebel Eltron Tempra 36 Plus is a refined, steady-temperature choice. For natural gas performance, the Rinnai RXP160iN offers an excellent balance of efficiency and household capacity. For propane users, the Ranein is a compact indoor option for smaller spaces. For outdoor and budget use, the Camplux Portable Propane Tankless Water Heater is practical and affordable. For high-demand homes, the Rinnai RX199iN is the premium upgrade with the most muscle.

Before purchasing, confirm fuel type, flow rate, installation requirements, water hardness, and local code rules. A well-chosen tankless water heater can save space, improve efficiency, and keep hot water coming when your household needs it most. Choose poorly, and your shower may become a motivational ice bath. Choose wisely, and hot water becomes one less thing to argue about.