The best condensing water heaters provide unparalleled energy efficiency and consistent hot water for households that prioritize savings and environmental responsibility. Unlike traditional tank models, these advanced units recapture heat from exhaust gases, significantly reducing energy waste and lowering utility bills. Without careful consideration, selecting the wrong unit can lead to inadequate hot water supply or wasted energy, diminishing the system’s cost-saving benefits.
Factors like capacity, venting requirements, and smart features vary widely, impacting performance and installation complexity. To help you make an informed decision, we’ve rounded up the top 10 best condensing water heaters available today, offering a blend of innovation, reliability, and outstanding performance for your home.
When selecting the best condensing water heaters, consider models like the Rinnai RX199iN or the Rheem Prestige Condensing Tankless. These units are notable for their One Model, Anywhere versatility, allowing for indoor or outdoor installation. They also feature Smart Sense technology, enabling them to operate on either natural gas or propane, offering significant flexibility for various home setups.
Best Condensing Water Heaters at a Glance
| Image | Product | Buy |
|---|---|---|
Best Pick 1  | NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Best for: Smart home upgrade | Check Price |
Best Pick 2  | Rinnai RE199iN Non-Condensing Natural Gas Tankless Water Heater, 199,000 BTU, Best for: Budget water heating | Check Price |
Best Pick 3  | Westinghouse Smart Tankless Water Heater Gas Indoor, 7.9 GPM 180,000 Best for: High-flow homes | Check Price |
Best Pick 4  | Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Best for: Outdoor installation | Check Price |
Best Pick 5  | Rheem Liquid Propane Condensing Tankless Water Heater Indoor Up To Best for: Propane users | Check Price |
How We Picked
To determine the best condensing water heaters, we prioritized real-world performance and durability. Models were evaluated on their build quality, safety features, and innovative standout features like indoor/outdoor versatility and dual-fuel capability across natural gas and propane. We ruled out non-condensing units outright to focus solely on advanced efficiency.
Extensive research informed our assessment, ensuring the selected models offer exceptional long-term value and consistent hot water delivery for demanding households.
What Most Buyers Get Wrong
Condensing Efficiency: Unlocking Gas Savings
Condensing tankless water heaters offer superior energy efficiency by capturing heat from exhaust gases that traditional units vent. Look for the Energy Factor (EF) rating; while not explicitly provided for all these models, a higher EF means more energy converted to hot water. This technology, seen in models like the Rinnai RX199iN and Rheem Prestige, is crucial for minimizing gas consumption and lowering utility bills over time compared to non-condensing units.
Indoor/Outdoor Versatility for Flex Installation
A key advantage of many top-tier condensing models is their dual indoor/outdoor installation capability. This flexibility, highlighted by the Rinnai RX199iN and Rheem Liquid Propane Condensing model, is often facilitated by specialized venting systems like Rinnai’s Versa Vent. This feature is vital for homeowners with limited indoor space or those seeking to optimize exterior aesthetics, bypassing the need for dedicated ventilation runs.
1. NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane
Best for: Indoor/Outdoor Propane or Natural Gas Use.
This Rinnai RX199iN offers a Versa Vent system for flexible indoor or outdoor installation, allowing placement anywhere your home needs a compact tankless unit.
With a Smart Sense gas control system and a maximum flow rate of 11.1 GPM, this unit efficiently heats water for up to 7 fixtures simultaneously, consuming only 98 watts of power.
Pros
- Versa Vent system for indoor/outdoor installation
- Smart Sense gas control for propane or natural gas
- Up to 11.1 GPM flow rate
- Smart Home Compatible
Cons
- Requires RX-OVC vent cap for outdoor installations.
For homeowners seeking versatile placement options and continuous hot water, this Rinnai model is an excellent choice. Its smart technology ensures efficient operation for busy households.
2. Rinnai RE199iN Non-Condensing Natural Gas Tankless Water Heater, 199,000 BTU,
Best for: High BTU Non-Condensing Performance.
The Rinnai RE199iN delivers 199,000 BTUs of heating power on demand, ensuring continuous hot water for multiple simultaneous uses in your home.
This non-condensing natural gas unit provides up to 9.8 GPM with a compact, wall-mounted design featuring an LED display for easy monitoring and maintenance diagnostics.
Pros
- 199,000 BTU high-performance heating
- Up to 9.8 GPM flow rate for continuous hot water
- Compact wall-mounted design
- LED display with diagnostic codes
Cons
- Non-condensing design means lower energy efficiency compared to condensing models.
Ideal for larger homes needing substantial hot water supply, this Rinnai heater offers reliable on-demand performance. Its space-saving design makes it suitable for various installation locations.
3. Westinghouse Smart Tankless Water Heater Gas Indoor, 7.9 GPM 180,000
Best for: Smart WiFi App Control for Whole Homes.
The Westinghouse Smart Tankless Water Heater provides up to 7.9 GPM with precise ±1℉ temperature control, ensuring consistent hot water for 3-5 fixtures simultaneously.
This 180,000 BTU unit connects via WiFi, allowing full control through a smartphone app to adjust settings and monitor operation remotely. It features overheat protection and easy installation.
Pros
- Up to 7.9 GPM flow rate
- Smart WiFi app control
- Precise ±1℉ temperature adjustment
- 180,000 BTU heating output
Cons
- Only 2-5 Years after-sale support mentioned, potentially shorter than some competitors.
For tech-savvy homeowners prioritizing convenience and control, this Westinghouse model is ideal. Manage your hot water needs from anywhere using the intuitive smartphone app.
4. Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Best for: Outdoor Installation, Natural Gas.
The Rheem RTG-84XLN-3 offers an 8.4 GPM flow rate for 2-3 bathroom homes, providing ample hot water for showers and laundry with its 180,000 BTU natural gas heating.
This high-efficiency, non-condensing outdoor unit features Hot-start Programming to reduce cold water bursts and a durable metal cabinet designed for easy wall mounting.
Pros
- 8.4 GPM flow rate for multiple bathrooms
- 180,000 BTU heating capacity
- Designed for outdoor installation
- Hot Start Programming
Cons
- Not Smart Home Compatible.
This Rheem tankless water heater is perfectly suited for households with moderate hot water demands that require an outdoor natural gas solution. Its robust design ensures reliable performance.
5. Rheem Liquid Propane Condensing Tankless Water Heater Indoor Up To
Best for: Indoor Propane Condensing Unit.
This Rheem liquid propane condensing tankless water heater delivers a flow rate of 0.4 to 6.8 GPM, ideal for smaller homes or supplementary hot water needs.
With a maximum temperature of 140°F and 120 BTUs of heat output, this indoor unit features an electric ignition for efficient operation and overheat film wrap for safety.
Pros
- Condensing technology for high efficiency
- 0.4 – 6.8 GPM flow rate range
- Indoor installation
- Electric ignition
Cons
- Low 120 BTU heat output is significantly less powerful than other models.
Homeowners opting for liquid propane and seeking an energy-efficient indoor unit will find this Rheem model suitable for moderate water usage. Its compact size is a benefit for limited spaces.
6. Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane
Best for: Commercial-Grade Condensing Heater.
The Rinnai CX199iN is a condensing tankless water heater with a high flow rate of 11.1 GPM, capable of supporting up to 7 fixtures simultaneously for demanding commercial or residential use.
This model utilizes Smart Sense gas control and Versa Vent technology, offering flexibility for natural gas or propane fuel and indoor/outdoor installation with a 199,000 BTU output.
Pros
- Up to 11.1 GPM flow rate
- Condensing technology for 96% efficiency
- Smart Sense gas control for fuel flexibility
- Indoor/outdoor installation capability
Cons
- Higher 600 watt power consumption compared to some residential units.
Businesses or large homes requiring robust and continuous hot water will benefit from this commercial-grade Rinnai heater. Its high capacity ensures no interruptions even during peak demand.
7. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water
Best for: Indoor Natural Gas, 7 GPM.
This Rheem RTG-70DVLN-3 tankless water heater provides 7.0 GPM capacity, ensuring sufficient hot water for 2-3 bathroom homes with its 160,000 BTU natural gas heating.
Designed for indoor installation, this high-efficiency, non-condensing unit features a durable and compact metal cabinet and includes Hot-start Programming to minimize cold water discharge.
Pros
- 7.0 GPM flow rate
- 160,000 BTU heating capacity
- Indoor installation
- Hot-start Programming
Cons
- Not Smart Home Compatible.
For residences with moderate hot water needs that require an indoor natural gas setup, this Rheem unit offers a reliable and efficient solution. It’s a solid choice for standard household use.
8. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water
Best for: Outdoor Propane, Compact Design.
The Rheem RTG-70XLP-3 delivers 7.0 GPM of hot water for homes with 2-3 bathrooms, powered by 180,000 BTUs of liquid propane with a compact and lightweight design.
This high-efficiency, non-condensing outdoor unit features industry-best side-to-side clearance for easier installation and 1/2 gas line compatibility for flexible setup.
Pros
- 7.0 GPM flow rate
- 180,000 BTU heating capacity
- Compact and lightweight outdoor design
- Industry-best side-to-side clearance
Cons
- Uses AC/DC power source, which might be less common than standard AC only.
This Rheem tankless water heater is ideal for outdoor liquid propane installations where space is a consideration and consistent hot water for multiple fixtures is needed. Its design simplifies mounting.
9. Rheem Prestige Condensing Tankless Gas Indoor Natural Gas Water Heater
Best for: Smart Condensing Natural Gas Indoor.
The Rheem Prestige Condensing Tankless offers 11 GPM flow rate with a .94 UEF efficiency rating, reducing water and energy waste for continuous hot water supply.
This indoor natural gas unit features Auto-Learn Programming to anticipate hot water needs and includes water and gas leak detection for enhanced safety, with a 199,000 BTU output.
Pros
- 11 GPM flow rate
- .94 UEF high efficiency
- Auto-Learn Programming
- Water & Gas Leak Detection
Cons
- Requires floor mount installation, which may differ from preferred wall mounting.
Homeowners seeking an energy-efficient and intelligent natural gas water heater will appreciate this Rheem Prestige model. Its smart features cater to modern households prioritizing savings and safety.
10. Rheem RTG-70DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water
Best for: Indoor Liquid Propane, 7 GPM.
This Rheem RTG-70DVLP-3 tankless water heater provides a 7.0 GPM flow rate for 2-3 bathroom homes, powered by 160,000 BTUs of liquid propane with a durable metal cabinet.
Designed for indoor installation, this high-efficiency, non-condensing 0.82 UEF unit ensures fast, reliable hot water and features Hot-start Programming to reduce temperature fluctuations.
Pros
- 7.0 GPM flow rate
- 160,000 BTU heating capacity
- Indoor installation
- Hot-start Programming
Cons
- Lowest efficiency rating (0.82 UEF) among listed models.
For homes using liquid propane that need reliable hot water for multiple bathrooms, this Rheem indoor unit is a practical choice. Its durable construction supports easy wall mounting.
Condensing vs. Non-Condensing: The Real Efficiency Trade-Off
The fundamental distinction when selecting among best condensing water heaters, and their non-condensing counterparts like the Rinnai RE199iN Non-Condensing Natural Gas Tankless Water Heater, 199,000 BTU, lies not in initial purchase price, but in long-term operational cost and installation requirements. Condensing units, such as the NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane and the Rheem Prestige Condensing Tankless Gas Indoor Natural Gas Water Heater, capture additional heat from exhaust gases. This process, while yielding higher energy efficiency ratings, generates a condensate that must be safely drained, often requiring a condensate pump and a dedicated drain line.
Failure to adequately plan for this drainage complicates installation and can negate the efficiency gains through added system complexity. Non-condensing models avoid this entirely; for instance, the Rheem RTG-84XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water heater, with its 180,000 BTUs, offers simpler venting and no condensate risk, making it a more straightforward choice for many existing setups.
This critical installation difference means that simply chasing the highest AFUE (Annual Fuel Utilization Efficiency) can lead to unforeseen expenses and complications, particularly when comparing units like the Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane against models like the Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water. The Westinghouse Smart Tankless Water Heater Gas Indoor, 7.9 GPM 180,00
What to Look For in Best Condensing Water Heaters
Energy factor ef ratings
When choosing a condensing water heater, prioritize the highest Energy Factor (EF) or Uniform Energy Factor (UEF) rating. Look for ratings of 0.90 and above for significant annual savings. While EF measures efficiency at a single point, UEF accounts for various operating conditions, making it a more comprehensive indicator.
Higher ratings mean less energy wasted as heat escapes the tank or byproducts. Opt for models with UEF ratings of 0.95 or higher to maximize your return on investment through reduced utility bills.
Tank capacity and flow rate
Select a tank capacity that precisely matches your household’s peak demand. For smaller households of one to two people, a 40-gallon tank is often sufficient. Families of three to four will perform best with a 50-gallon unit, while larger households or those with high usage might need a 75-gallon tank.
Critically, match this to the Gallons Per Minute (GPM) rating to ensure hot water availability during peak times. For consistent high-demand use, select a unit with a minimum 6 GPM flow rate capability.
Venting requirements and installation
Proper venting is critical for both performance and safety with condensing water heaters. Choose units that utilize PVC or CPVC venting for their durability and ease of installation in most residential settings. Ensure sufficient space for both air intake and exhaust vent pipes, typically requiring 1-inch diameter pipes for these materials.
Flexible venting is an option for specific retrofits, but always verify code compliance. Prioritize models with clear venting instructions to guarantee safe and efficient operation.
Ignition type and control systems
For modern condensing water heaters, an electronic ignition system is the superior choice, offering reliability and eliminating the constant energy draw of a standing pilot light. Look for models with digital displays that provide clear temperature settings and diagnostic information. These advanced control systems monitor performance and can alert you to potential issues, simplifying troubleshooting.
Select a unit with integrated diagnostics for straightforward maintenance and long-term operational confidence.
Which Should You Choose?
- If you need to power your heater with either natural gas or propane and require indoor/outdoor flexibility, choose a model with “Smart Sense” gas control and “Versa Vent” technology.
- If you’re replacing a traditional tank heater and value space savings and lower operating costs, look for a compact, high-efficiency condensing model with leak detection features.
- If you need continuous hot water for multiple bathrooms and appliances, opt for a high-GPM tankless model with a high BTU output.
- If you have a limited budget and primarily need on-demand hot water for a standard-sized home without extreme demands, a non-condensing tankless heater might suffice.
Quick Best Condensing Water Heaters Buying Checklist
- Energy Factor (EF) Rating: Look for models with high EF ratings, ideally above 0.90, for maximum efficiency and cost savings.
- Tank Capacity: Select a tank size (e.g., 50-gallon) that comfortably meets your household’s daily hot water demands without frequent reheating.
- Flow Rate (GPM): Ensure the water heater can deliver enough hot water quickly (gallons per minute) to support multiple simultaneous uses.
- Venting Options: Confirm the unit’s venting compatibility (PVC, CPVC) with your home’s existing or planned setup for easier installation.
- Ignition Type: Opt for electronic ignition for quicker heating and reduced energy waste compared to older pilot light systems.
- Warranty and Support: Check the manufacturer’s warranty on tank and parts, as well as available customer support, for long-term peace of mind.
Frequently Asked Questions
What Is The Primary Benefit Of A Condensing Water Heater?
The primary benefit of a condensing water heater is its superior energy efficiency, achieved by capturing waste heat from exhaust gases. This pre-heats incoming cold water, significantly reducing the energy needed to heat your supply and leading to lower utility bills over time.
How Does Tank Capacity Affect Performance For Best Condensing Water Heaters?
Tank capacity directly impacts how much hot water is available at any given time. For best condensing water heaters, choosing a capacity appropriate for your household’s peak demand prevents running out of hot water and ensures consistent supply for all needs.
Why Is The Energy Factor (Ef) Rating Crucial For These Units?
The Energy Factor (EF) rating is crucial because it quantifies a water heater’s energy efficiency. Higher EF ratings, typically above 0.90 for condensing models, mean less energy is wasted, translating to significant operational cost savings and a reduced environmental impact.
What Are Common Venting Materials Used By These Models?
Common venting materials for these water heaters include PVC, CPVC, and sometimes flexible venting options, depending on local codes and manufacturer specifications. Proper venting is essential for safely expelling exhaust gases and ensuring optimal performance.
Can I Install A Condensing Water Heater In A Small Space?
Yes, many condensing water heaters are designed for compact installation, but proper clearance for venting is still essential. Always consult the manufacturer’s manual for specific space requirements to ensure safe and efficient operation.
Final Words
Investing in the best condensing water heaters offers substantial long-term savings and environmental benefits due to their advanced energy-efficient technology. With higher efficiency ratings and smart design features, these units provide reliable hot water while minimizing energy consumption. Choosing a model suited to your needs will ensure years of dependable, cost-effective performance.
