Best RU199 Tankless Water Heaters

Finding the right water heater can feel overwhelming, especially when you’re faced with choices between traditional tanks and modern tankless options. If you’ve ever run out of hot water during a shower or waited endlessly for the tap to warm up, you know the frustration firsthand. The transition to a tankless water heater can solve these problems, providing endless hot water while saving space and energy.

A high-quality tankless water heater can deliver on-demand hot water, reducing energy waste significantly compared to traditional water heaters. It’s essential to consider factors such as flow rate, energy efficiency, and installation requirements to find the right fit for your home. The best models offer reliability and performance, ensuring your hot water needs are met without compromise.

In this review, we’ll explore the top five RU199 tankless water heaters currently available. From compact electric heaters ideal for smaller homes to robust gas models capable of servicing larger households, we’ll break down their features, pros and cons, and help you determine which model is best suited for your needs.

Comparing key specifications can help you make an informed choice. Here’s a quick look at our top picks:

Features	Rinnai RE199iN	110V Tankless Heater	Rheem 18kW Heater	NOVIEEX 18kW Heater	Rinnai RX199iN
Material & Build	Gas, Non-condensing	Electric, Stainless Steel	Electric, Copper	Electric, Compact Design	Gas, Condensing
Key Specification	9.8 GPM, 199k BTU	3000W, 0.3-0.5 GPM	Up to 4.4 GPM	Up to 4.9 GPM	11.1 GPM, 199k BTU
Main Feature	Endless Hot Water	Instant Heating	Self-modulating	Anti-scald Technology	Smart Sense Control
Performance	Whole House Use	Compact, Under Sink	Easy Installation	High Efficiency	Indoor/Outdoor Use
Best Use Case	Large Households	Small Spaces	Medium Homes	Small to Medium Homes	Multiple Fixtures

Rinnai RE199iN Non-Conden…

The Rinnai RE199iN is an exceptional gas tankless water heater designed for whole-house use. It’s perfect for larger households that require a reliable and consistent supply of hot water for multiple fixtures simultaneously, such as showers, dishwashers, and laundry machines.

One of the standout features of this model is its impressive 9.8 gallons per minute (GPM) flow rate, which can comfortably support several hot water demands at once. The energy-efficient, non-condensing design heats water on demand, minimizing energy waste. Additionally, its compact, wall-mounted design saves valuable space in your home.

On the downside, this unit requires professional installation due to its gas line connections and venting needs. Some users might also find the upfront cost to be higher compared to electric options. However, the long-term savings on energy bills can offset this initial investment.

• Flow Rate: 9.8 GPM
• Heating Capacity: 199,000 BTU
• Energy Efficient: Non-condensing
• Durability: 15-year heat exchanger warranty
• Ideal for: Large households

Best for: Families needing a reliable source of hot water for multiple appliances.

110V Tankless Water Heate…

This 110V electric tankless water heater offers a compact solution for spaces that require instant hot water, such as kitchens and bathrooms. It’s particularly suitable for apartments, RVs, and small homes where traditional hot water tanks might take up too much space.

The heater’s 3000W power allows it to raise water temperatures from 82°F to 131°F almost instantly, eliminating the wait time for hot water. The unit is designed with safety features such as IPX4 waterproofing and dry boil protection, making it a reliable choice for various applications.

However, it’s important to note that this heater isn’t suitable for shower use, as it typically requires a flow rate of at least 1.8 GPM, which this unit does not provide. Additionally, installation must be vertical only, which might limit placement options.

• Power: 3000W
• Flow Rate: 0.3-0.5 GPM
• Safety Features: Leakage protection
• Installation: Under sink
• Ideal for: Small spaces

Best for: Users needing instant hot water in small areas.

Rheem 18kW 240V Tankless…

The Rheem 18kW electric tankless water heater is designed for medium-sized homes. With a flow rate of up to 4.4 GPM, it can effectively meet the hot water needs of several fixtures running at once, making it a solid choice for families.

This unit features self-modulating technology, adjusting power to meet demand, which enhances energy efficiency. Its durable copper immersion heating elements ensure reliable performance and easy maintenance, making this model a favorite among homeowners.

While the Rheem is efficient, some users may find the installation process slightly challenging due to its bottom water connections. Additionally, it may require a larger electrical service, which could add to the installation cost.

• Flow Rate: Up to 4.4 GPM
• Power: 18kW
• Heating Elements: Copper
• Installation: Bottom connections
• Ideal for: Medium homes

Best for: Mid-sized households wanting efficient hot water.

18kW Tankless Water Heate…

The NOVIEEX 18kW tankless water heater is a powerful choice for small to medium homes. It delivers a maximum flow rate of 4.9 GPM, making it capable of handling simultaneous use across multiple faucets and appliances without a drop in temperature.

Featuring an anti-scald constant temperature control, this unit maintains a consistent water temperature, ensuring safety and comfort. Its compact design maximizes space efficiency, freeing up room compared to traditional tank heaters. With a 99.8% thermal efficiency, it significantly reduces energy costs.

Despite its efficiency, the NOVIEEX requires a robust electrical setup, including two 40A double-pole circuit breakers, which may involve additional installation costs. Potential buyers should ensure their electrical system meets these requirements before purchasing.

• Flow Rate: Up to 4.9 GPM
• Power: 18kW
• Efficiency: 99.8%
• Temperature Control: Anti-scald
• Ideal for: Small to medium homes

Best for: Households needing efficient hot water for multiple fixtures.

Rinnai RX199iN Condensing…

This Rinnai RX199iN is a versatile condensing tankless water heater that operates on both natural gas and propane, making it suitable for various installation scenarios, including indoor or outdoor settings. With a flow rate of 11.1 GPM, it can serve multiple fixtures simultaneously, ideal for busy households.

The unit’s Smart Sense technology optimizes performance by adjusting to water demand, ensuring energy efficiency and consistent hot water supply. Its compact design makes it space-efficient, similar to the size of a small suitcase.

However, professional installation is recommended due to its venting and gas connections, which may deter DIY enthusiasts. While it offers many advanced features, its upfront cost may be higher than simpler models.

• Flow Rate: 11.1 GPM
• Heating Capacity: 199,000 BTU
• Fuel Type: Natural gas/propane
• Installation: Indoor/Outdoor
• Ideal for: Large households

Best for: Families needing versatile hot water solutions.

How We Chose These Products

Our selection process involved evaluating each tankless water heater based on key performance metrics such as flow rate, energy efficiency, and user feedback. We also considered installation requirements and overall reliability, ensuring that each product we recommend is well-suited for typical household needs.

We focused on a variety of models to cater to different buyer preferences—whether looking for electric or gas options, compact solutions, or high-capacity systems. Our goal was to provide a comprehensive overview, allowing readers to choose the best tankless water heater for their unique situations.

Buying Guide: What Really Matters

When selecting a tankless water heater, consider the flow rate, which indicates how many fixtures can be used simultaneously without a drop in hot water supply. Higher flow rates are essential for larger households or homes with multiple bathrooms.

Energy efficiency is another crucial factor. Look for models with high thermal efficiency ratings, as these can significantly lower your utility bills in the long run. Additionally, think about the installation requirements. Some units require professional installation due to gas connections or electrical needs, which may impact your overall costs and convenience.

Our Top Recommendation

The Rinnai RE199iN stands out as the best overall tankless water heater due to its impressive performance, energy efficiency, and long-lasting durability. It’s ideal for large households needing reliable hot water for multiple applications. For those on a tighter budget or with smaller space needs, the 110V Tankless Water Heater is a great alternative.

Frequently Asked Questions

What is the lifespan of a tankless water heater? Most tankless water heaters can last over 20 years with proper maintenance, making them a long-term investment.

How do I maintain my tankless water heater? Regular maintenance includes descaling the unit annually, checking for leaks, and ensuring the vents are clear.

Can I install a tankless water heater myself? While some models allow for DIY installation, it’s generally recommended to hire a professional, especially for gas models.

What size tankless water heater do I need? The size depends on your household’s hot water needs. Calculate your required flow rate based on fixtures you plan to use simultaneously, then select a model that meets those specifications.