What Is The Best Tankless Water Heater?

Choosing the ideal tankless water heater is a significant decision for any homeowner seeking efficiency, convenience, and long-term savings. Unlike traditional tank-based systems that store and continuously heat a reservoir of water, tankless units heat water on demand, providing a continuous supply without the wait or the waste. This innovative approach not only ensures you never run out of hot water, even during peak usage, but also drastically reduces energy consumption by eliminating standby heat loss. The “best” unit, however, is not a one-size-fits-all answer; it depends heavily on individual household needs, local utility availability, and specific performance expectations.

Understanding Tankless Water Heater Technologies

Tankless water heaters primarily come in two major types: electric and gas. Each offers distinct advantages and considerations that influence their suitability for different applications. Evaluating these foundational technologies is the first step in narrowing down your options and identifying the system that aligns with your lifestyle and infrastructure.

Electric Tankless Water Heaters

Electric tankless units are generally more compact and simpler to install, requiring no venting or gas lines. This makes them an excellent choice for smaller homes, apartments, or point-of-use applications like a remote bathroom sink or a specific appliance. They operate by using high-powered heating elements to rapidly warm water as it flows through the unit.

• Advantages:
  • Compact Size: Their small footprint allows for flexible installation in tight spaces, including under sinks or in utility closets.
  • Lower Installation Costs: No need for gas line installation or elaborate venting systems, often resulting in reduced labor costs.
  • Environmental Impact: Produce zero direct emissions at the point of use, making them a greener option if your electricity comes from renewable sources.
  • Safety: No risk of carbon monoxide leaks, which is a concern with gas appliances.
• Considerations:
  • High Electrical Demands: They typically require dedicated high-amperage electrical circuits, often 200 amps or more for whole-home units, which may necessitate electrical panel upgrades in older homes.
  • Operating Costs: Electricity can be more expensive than natural gas or propane in many regions, leading to higher energy bills over time, especially for high-demand applications.
  • Flow Rate Limitations: Larger homes with multiple simultaneous hot water demands might find electric units struggling to keep up, potentially delivering lower flow rates or slightly cooler water temperatures.

Gas Tankless Water Heaters (Natural Gas & Propane)

Gas tankless heaters, fueled by natural gas or liquid propane (LP), are powerful units capable of handling substantial hot water demands, making them popular for larger households. They utilize a high-efficiency burner to heat water quickly and effectively, providing robust flow rates.

• Advantages:
  • Higher Flow Rates: Generally offer superior flow rates and temperature consistency compared to electric units, comfortably supporting multiple hot water applications simultaneously.
  • Lower Operating Costs: Natural gas and propane are often more cost-effective energy sources than electricity in many areas, leading to lower monthly utility bills.
  • Faster Heating: Gas burners typically heat water more rapidly, ensuring a quicker response to hot water demand.
• Considerations:
  • Venting Requirements: Require proper venting to expel combustion byproducts, which can add complexity and cost to installation. Condensing models often use PVC or CPVC, while non-condensing units typically require more expensive stainless steel.
  • Gas Line Infrastructure: A dedicated gas line of adequate size is essential. Homes without existing gas lines will incur significant installation costs for new line installation.
  • Higher Initial Cost: The units themselves can be more expensive than electric counterparts, and installation complexity further drives up the total cost.
  • Maintenance: Require periodic professional maintenance, including flushing to prevent mineral buildup and ensure optimal performance.

Key Factors in Selecting the Best Unit

Beyond the core technology, several critical factors must be carefully evaluated to ensure the tankless water heater you choose is truly the “best” for your specific circumstances. Overlooking any of these could lead to insufficient performance, unexpected costs, or dissatisfaction.

Sizing and Flow Rate

This is arguably the most crucial factor. Tankless water heaters are sized by their flow rate (measured in gallons per minute, GPM) and temperature rise capability. To determine the right size, you need to estimate your household’s peak hot water demand.

• Calculate Peak GPM: List all hot water appliances and fixtures that might run simultaneously (e.g., two showers, a dishwasher, a washing machine). Add up their individual GPM requirements. For example, a shower typically uses 2.5 GPM, a dishwasher 1.5 GPM, and a bathroom sink 1 GPM. If two showers and a dishwasher are running, you’d need at least a 6.5 GPM unit.
• Consider Temperature Rise: The unit’s ability to heat water is affected by the incoming water temperature. In colder climates, where groundwater is much cooler, the unit will need more BTU/kW power to achieve the desired hot water temperature, which will reduce its effective GPM output. Manufacturers typically provide charts showing GPM at various temperature rises. Ensure the unit can provide your required GPM at your specific climate’s temperature rise.

Energy Efficiency and Operating Costs

While all tankless units are inherently more efficient than traditional tanks, there’s still a range of efficiency among models.

• Energy Factor (EF) / Uniform Energy Factor (UEF): These ratings indicate a water heater’s overall energy efficiency. Higher numbers mean better efficiency. Look for units with UEF ratings of 0.82 or higher for gas models, and close to 0.99 for electric models.
• Condensing vs. Non-Condensing (Gas Only): Condensing gas tankless units capture latent heat from exhaust gases, making them significantly more efficient (UEF 0.90+) than non-condensing units (UEF 0.82-0.85). While typically more expensive upfront, their lower operating costs can lead to substantial long-term savings.
• Modulation: Many tankless heaters feature self-modulating technology, which means they can adjust their heating output based on the hot water demand. This prevents the unit from operating at full power unnecessarily, saving energy and extending its lifespan.

Installation and Venting

Professional installation is critical for tankless water heaters to ensure safety, efficiency, and compliance with local codes.

• Location: Tankless units can be installed indoors or outdoors, depending on the model. Outdoor units save indoor space but must be protected from freezing.
• Venting (Gas): Proper venting is non-negotiable for gas units. Non-condensing units typically require category III stainless steel venting, which is more expensive. Condensing units use less costly PVC or CPVC piping. Incorrect venting can be dangerous and inefficient.
• Electrical Requirements (Electric): Verify your home’s electrical panel capacity. Large electric tankless heaters often require multiple high-amperage breakers.
• Gas Line Sizing (Gas): Existing gas lines might need upgrading to accommodate the higher BTU demand of a tankless heater.

Advanced Features and Brands to Consider

Modern tankless water heaters often come equipped with features that enhance convenience, longevity, and control. While the “best” brand can be subjective, certain manufacturers consistently deliver reliable and high-performing products.

Desirable Features

• Built-in Recirculation Pump: For homes with long plumbing runs, this feature reduces the wait for hot water at the tap, significantly enhancing user convenience.
• WiFi Connectivity: Allows for remote monitoring and control of the unit via a smartphone app, enabling temperature adjustments, usage tracking, and system diagnostics from anywhere.
• Self-Modulation: As mentioned, this critical feature optimizes energy consumption by matching heating output to demand.
• Freeze Protection: Essential for units installed in unconditioned spaces or colder climates, preventing damage from freezing temperatures.
• Low NOx Burners: For gas units, these minimize nitrogen oxide emissions, making them more environmentally friendly.
• Digital Displays and Controls: Provide precise temperature settings and diagnostic information, making operation and troubleshooting straightforward.

Reputable Brands

While specific models evolve, a few brands consistently rank high in performance, reliability, and customer satisfaction for tankless water heaters:

• Rinnai: A leader in gas tankless technology, known for high efficiency, durability, and a wide range of models.
• Noritz: Offers robust gas tankless heaters with excellent flow rates and advanced features, often favored by professionals.
• Navien: Specializes in condensing gas tankless units and combination boilers (heating both domestic hot water and space heating), known for efficiency and compact design.
• Rheem/Ruud: Well-established names in water heating, offering reliable tankless solutions in both gas and electric.
• Bosch: Known for German engineering, producing high-quality electric and gas tankless units.
• EcoSmart: Popular for electric tankless models, especially for point-of-use or smaller whole-home applications, due to their compact size and competitive pricing.

The Verdict: Tailoring the Choice to Your Home

Ultimately, the best tankless water heater is the one that perfectly matches your household’s hot water demands, fits within your budget for both purchase and installation, and aligns with your long-term energy cost expectations. There isn’t a single universal winner because factors like local utility rates, the number of occupants, climate, and existing home infrastructure play a decisive role.

Start by meticulously calculating your peak GPM requirements, then consider your energy source availability and cost. Electric tankless heaters excel in simplicity and compact applications, while gas units (natural gas or propane) offer superior power and lower operating costs for larger households. Investigate models with advanced features like self-modulation, recirculation, and smart connectivity that can enhance efficiency and user experience. Always prioritize professional installation to ensure safety and optimal performance, safeguarding your investment for years to come. By carefully weighing these factors, you can confidently select a tankless water heater that provides endless hot water efficiently and reliably, becoming a truly invaluable upgrade to your home.