Best Indirect Water Heaters: Top 10 Picks Revealed
Delving into hydronic heating systems, the best indirect hot water heater offers a highly efficient method for domestic hot water generation, leveraging your existing boiler. Unlike conventional tanks, these units utilize a heat exchanger to transfer thermal energy, providing an economical and robust solution for consistent hot water supply. Understanding the nuances of indirect water heaters, from tank insulation to exchanger performance, is key to selecting a model that optimizes energy savings and minimizes operational costs within your plumbing setup.
This exploration into the top indirect water heater models will illuminate the innovations and features that set them apart, promising superior performance and longevity for discerning homeowners. Uncover which indirect tank systems excel in delivering unparalleled efficiency and reliability.
Find Your Perfect Indirect Water Heater
1. NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane
Experience uninterrupted hot water with the Rinnai RX199iN Condensing Tankless Water Heater, a revolutionary solution engineered for ultimate flexibility and efficiency. This intelligent gas water heater adapts to your needs, offering a reliable and compact way to ensure hot water is always on demand, making it a top contender for the best indirect hot water heater replacement.
The Rinnai RX199iN boasts an innovative Smart Sense gas control system, allowing seamless operation with either natural gas or propane. Its compact design, comparable to a small suitcase, belies its powerful performance, delivering up to
With a high energy efficiency rating of UEF .98, this unit significantly reduces energy consumption, positioning it as a leading condensing natural gas water heater or condensing propane water heater.
Pros
- Versatile Installation: The innovative Versa Vent system enables both indoor and outdoor installation, offering unparalleled placement flexibility for your tankless gas water heater. An outdoor vent cap (RX-OVC) is required for exterior setups.
- Continuous Hot Water Supply: Never face a cold shower again. This unit provides a high flow rate of 11 GPM, capable of running up to 7 fixtures at once, ideal for busy households.
- High Energy Efficiency: Achieve significant savings on utility bills thanks to its super-high Uniform Energy Factor (UEF) of .98, making it one of the most efficient tankless water heaters available.
- Smart Technology Integration: While requiring an optional Controlr module, the unit offers smart home compatibility for WiFi control, allowing for remote monitoring and management of your water heating system.
- Compact and Discreet: Its small footprint makes it an excellent choice for homes where space is limited, easily fitting into various installation locations.
Cons
- Professional Installation Required: Due to the complexity of gas and venting systems, professional installation is strongly recommended and crucial for optimal performance and safety, which adds to the overall cost beyond the unit price.
The Rinnai RX199iN Condensing Smart Sense Tankless Water Heater is an exceptional choice for homeowners seeking a reliable, efficient, and versatile hot water solution. Its ability to run on either natural gas or propane, coupled with its compact size and high-performance output, makes it a standout option for continuous hot water needs in various home environments.
2. BOSCH Electric Mini-Tank Water Heater Tronic 3000 T 2.5-Gallon (ES2.5)
Experience the convenience of instant hot water exactly where you need it with the BOSCH Tronic 3000 T 5-Gallon Mini-Tank Electric Water Heater.
This compact unit is designed for under-sink installation, delivering a near-endless supply of hot water for various domestic tasks, eliminating tedious waits. It’s an ideal solution for point-of-use hot water needs, offering exceptional thermal efficiency and lasting durability.
The BOSCH Tronic 3000 T provides 5 gallons of on-demand hot water, boasting a remarkable 98% thermal efficiency. Its robust construction features premium glass-lined material for extended service life, ensuring easy maintenance and reliable performance.
Its robust construction features premium glass-lined material for extended service life, ensuring easy maintenance and reliable performance. With independent installation capabilities via a standard 120-volt outlet and a 36-37 cord, it seamlessly integrates into your existing plumbing, supplying hot water to up to two sinks.
Pros
- Immediate Hot Water: Its compact 2.5-gallon capacity is perfectly sized for under-sink placement, delivering hot water directly at the tap, significantly reducing wait times and water waste compared to traditional tankless water heaters or larger storage tank models.
- Exceptional Energy Efficiency: With a 98% thermal efficiency, this electric mini-tank heater minimizes energy consumption, making it an economical choice for continuous hot water delivery at the point of use such as RVs, workshops, or remote sinks.
- Durable and Low Maintenance: Constructed with premium glass-lined material, the BOSCH Tronic 3000 T is built for longevity and ease of upkeep, ensuring a reliable hot water supply without the hassle of frequent servicing. This is a key benefit when looking for a long-lasting small electric water heater.
- Flexible Installation Options: Easily mounted on a shelf, wall, or floor using the included bracket, this electric mini-tank water heater offers versatile placement. Its 120-volt plug-in design simplifies setup, making it a great option for a quick-install hot water solution or as a booster for existing systems where continuous hot water is crucial.
Cons
- Limited Capacity for High Demand: While excellent for single-point-of-use applications or low-flow needs, the 2.5-gallon capacity might be insufficient for simultaneous high-demand uses like filling a large bathtub or running multiple appliances calling for hot water at once, unlike larger capacity tank or tankless models.
For households or individuals seeking a reliable, efficient, and compact hot water solution for specific locations like kitchen sinks, workshops, or RVs, the BOSCH Tronic 3000 T 5-Gallon Electric Mini-Tank Water Heater is an outstanding choice. Its point-of-use functionality and easy installation make it a practical upgrade for immediate hot water access without extensive plumbing modifications.
Its point-of-use functionality and easy installation make it a practical upgrade for immediate hot water access without extensive plumbing modifications.
3. Rheem 18kW 240V Tankless Electric Water Heater, Gray
Experience endless hot water on demand with the Rheem 18kW 240V Tankless Electric Water Heater. This compact, gray unit delivers efficient, continuous hot water, making it an ideal upgrade for homes seeking modern, space-saving, and energy-conscious water heating solutions without compromising comfort.
Engineered for performance, this Rheem tankless model features advanced self-modulation to precisely match its power output to your precise hot water needs. Its durable copper heating elements ensure longevity, while the external digital thermostatic control allows for easy temperature adjustment with exceptional +/- 1 degree Fahrenheit accuracy.
Pros
- Uninterrupted Hot Water Supply: Never run out of hot water again, perfect for busy households with simultaneous demand from multiple fixtures, providing up to 4.4 GPM (Gallons Per Minute) flow rate.
- Precise Temperature Control: The intuitive external LED display offers granular temperature management (accuracy of +/- 1°F), ensuring your water is always at the perfect setting for showers, dishes, and more.
- Advanced Efficiency and Modulation: Utilizes intelligent self-modulation to adjust power dynamically, optimizing energy consumption and delivering an impressive 99.8% energy efficiency, reducing utility bills compared to traditional tank heaters.
- Durable and Serviceable Design: Features field-serviceable copper immersion heating elements for long-lasting performance and easy maintenance, contributing to its overall reliability as a high-efficiency electric water heater.
- Streamlined Installation: Designed with bottom 3/4-inch NPT water connections and threaded fittings for straightforward replacement and simplified mounting, making it a convenient tankless water heater installation choice.
Cons
- Requires Dedicated Electrical Circuit: As an 18kW electric unit operating at 240V, it necessitates a substantial dedicated electrical circuit, which may require professional electrical work and potentially higher installation costs depending on existing home wiring.
The Rheem 18kW Tankless Electric Water Heater is an exceptional choice for homeowners prioritizing continuous hot water, precise temperature control, and energy savings. Its advanced technology and robust construction make it a reliable and efficient modern water heating system, particularly for those upgrading from older tank-style models.
4. InSinkErator HOT150 Instant Hot Water Dispenser System – Faucet &
Transform your kitchen tasks with the InSinkErator HOT150 Instant Hot Water Dispenser System. Experience the ultimate convenience of having near-boiling water ready at your fingertips, streamlining everything from culinary creations to effortless cleanups. This elegantly designed dispenser offers immediate access to hot water, saving you precious time and enhancing your daily kitchen routines.
This InSinkErator unit features a sleek, single-handle faucet and a compact 2/3-gallon stainless steel tank. Its user-friendly design allows for easy temperature adjustment and simple single-hole installation under your sink, making it a stylish and functional addition to any modern or transitional kitchen.
Ideal for cooking, cleaning, and preparing your favorite hot beverages, this dispenser provides hot water on demand.
Pros
- Instant Near-Boiling Water: Delivers hot water within seconds, significantly speeding up tasks like blanching vegetables, warming bottles, or dissolving stubborn grease.
- Space-Saving & Energy Efficient: The compact 2/3-gallon tank fits neatly under your sink, and its on-demand heating mechanism conserves energy compared to continuously heating a large water volume for kitchen hot water needs.
- Stylish Chrome Faucet: The modern, single-handle design complements various kitchen aesthetics, providing a clean and sophisticated look that pairs well with existing main faucets.
- Easy Temperature Control: Features an easily adjustable temperature setting, allowing you to customize the water heat precisely for different applications, from lukewarm to almost boiling.
- Convenient for Beverages & More: Perfect for making tea, coffee, hot chocolate, or quickly sanitizing utensils, offering exceptional utility for a hot water dispenser faucet.
Cons
- Requires Dedicated Electrical Outlet: Installation necessitates a nearby electrical source under the sink, which might add complexity to the setup if one isn’t readily available for your instant hot water system.
For those seeking an efficient and stylish solution for immediate hot water access, the InSinkErator HOT150 is an excellent choice. It elevates kitchen functionality by providing near-boiling water instantly, making it an indispensable tool for busy households that value speed, convenience, and sophisticated design in their kitchen appliances.
5. Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
Experience endless hot water on demand with the Rheem RTEX-13 Residential Tankless Water Heater. This compact, wall-mounted unit delivers exceptional energy efficiency and precise temperature control, making it an ideal upgrade for any modern home seeking reliable and efficient water heating solutions. Say goodbye to cold showers and hello to continuous comfort.
Say goodbye to cold showers and hello to continuous comfort.
This Rheem tankless water heater boasts a durable copper heating chamber and two field-serviceable elements for longevity. Its self-modulating power control ensures optimal performance, while the external digital thermostatic control with an LED display allows for 1-degree Fahrenheit temperature adjustments, guaranteeing your perfect water temperature every time.
17 GPM, making it a powerful electric tankless option for various household needs.
Pros
- Precise Temperature Management: An external digital thermostatic control with an LED display provides +/- 1-degree Fahrenheit accuracy, offering unparalleled comfort and avoiding scalding temperatures.
- High Energy Efficiency: Operating at 99.8% energy efficiency, this electric tankless model significantly reduces energy consumption and lowers utility bills compared to traditional tank heaters.
- Durable Construction: Featuring a robust copper immersion heating chamber and field-serviceable heating elements, this unit is built for long-lasting performance and reliability.
- Space-Saving Design: The compact, wall-mounted form factor frees up valuable floor space, ideal for homes where energy efficiency and space are paramount.
- Easy Installation: Included 1/2-inch NPT adapters and side compression water connections simplify the installation process for a swift upgrade.
Cons
- High Electrical Requirements: This 13kW unit requires a 240-volt connection and draws 54 amps, necessitating a dedicated circuit and potentially requiring electrical upgrades in some homes.
The Rheem RTEX-13 is an excellent choice for homeowners prioritizing instant, energy-efficient hot water for single or small-household use. Its advanced features and reliable performance make it a superior alternative to bulky, less efficient tank water heaters. Experience continuous hot water with smart technology.
6. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water
Experience continuous, on-demand hot water with the Rheem RTG-70DVLN-3, a high-efficiency non-condensing indoor tankless natural gas water heater. Designed for modern homes, this unit delivers exceptional performance, ensuring you never run out of hot water, even during peak demand.
This powerful natural gas water heater provides up to 0 GPM, ideal for households with 2-3 bathrooms. Its 160,000 BTU output guarantees rapid heating, while the integrated hot-start programming prevents cold water bursts, making every shower a comfortable experience.
The compact, wall-mountable design saves valuable space compared to traditional tank heaters.
Pros
- Delivers up to 7.0 GPM maximum flow rate, capable of supporting multiple hot water applications simultaneously in 2-3 bathroom homes.
- Hot-start programming ensures a consistent, continuous flow of hot water without the frustrating “cold water sandwich” effect, enhancing shower comfort.
- Space-saving, compact design allows for convenient indoor installation and wall mounting, freeing up floor space.
- High energy efficiency contributes to lower utility bills compared to older tank-style water heaters.
- Durable metal cabinet construction built for longevity and reliable indoor performance.
Cons
- Requires professional installation due to natural gas connection and venting requirements.
The Rheem RTG-70DVLN-3 is an excellent choice for homeowners seeking a reliable, energy-efficient, and space-saving solution for their hot water needs. Its continuous hot water supply and advanced features make it a superior alternative to cumbersome tank water heaters, perfect for busy households.
7. GE Appliances 10 Gallon Versatile Plug and Play Electric Water
Experience the convenience of instant, on-demand hot water with the GE Appliances 10 Gallon Versatile Plug and Play Electric Water Heater. This compact unit offers a simple, effective solution for boosting hot water supply precisely where you need it, making it an ideal addition for various home or recreational applications.
Engineered for effortless integration, this 10-gallon electric water heater connects directly to a standard 120-Volt supply, requiring no complex wiring. Its versatile design and adjustable thermostat allow for customized temperature settings, ensuring optimal comfort for tasks ranging from dishwashing to personal hygiene. A robust warranty provides long-term assurance.
Pros
- Effortless Installation: Installs quickly using existing plumbing connections (standard 3/4-in NPT) and a common 120-Volt outlet, simplifying setup for DIYers.
- Space-Saving Compactness: The 10-gallon capacity and streamlined profile make it an excellent fit for tight spaces such as under sinks, in RVs, cabins, or garages, adding hot water accessibility without consuming significant room.
- Flexible Hot Water Boosting: Functions superbly as a standalone point-of-use water heater or can be plumbed inline with your main water heater to increase the hot water available for appliances like washing machines or for extending hot water delivery across longer distances.
- Durable and Reliable: Backed by an 8-year limited tank and parts warranty, plus 1-year labor coverage, offering significant peace of mind regarding its longevity and performance.
- Precise Temperature Control: Features an easily adjustable thermostat, allowing users to set the water temperature precisely to their preferred levels, up to a maximum of 140°F.
Cons
- Limited Capacity for Whole-House Use: While ideal for supplementary or point-of-use applications, the 10-gallon capacity is generally insufficient to meet the full hot water demands of a larger household as a primary water heating solution.
The GE Appliances 10 Gallon Versatile Plug and Play Electric Water Heater is an excellent choice for anyone needing a supplementary hot water source that’s easy to install and operate. Its efficient design and flexible application make it a smart investment for enhancing comfort and convenience in smaller spaces or for specific high-demand fixtures.
8. SMART40 Phase III Indirect 36-Gallon Water Heater
Experience unparalleled hot water performance with the Triangle Tube SMART40 Phase III Indirect 36-Gallon Water Heater. This advanced system leverages revolutionary Tank-in-Tank technology to deliver abundant domestic hot water efficiently, ensuring your comfort while minimizing energy costs.
Discover superior heating and reliability for your home.
This 36-gallon indirect water heater stands out with its 2 thick polyurethane foam insulation, significantly reducing standby heat loss for maximum efficiency. The self-cleaning and self-descaling heat exchanger design ensures longevity and consistently high performance, providing a reliable and cost-effective hot water solution for your household needs. Enjoy a consistently warm supply with this dependable unit.
Pros
- Exclusive “Tank-in-Tank” technology maximizes hot water availability and minimizes runtime for significant cost savings on your energy bills.
- 2″ of dense polyurethane foam insulation offers superior thermal retention, keeping water hotter for longer and reducing heating cycles, which is essential for an efficient home water system.
- The self-cleaning/self-descaling heat exchanger design promotes system longevity and maintains optimal performance by preventing sediment buildup, ensuring a consistent supply of clean hot water.
- Boasting the industry’s lowest pressure drop, this indirect water heater ensures robust water flow throughout your home, providing a satisfying hot water experience even during high demand.
Cons
- As an indirect water heater, it requires a separate boiler or heat source to operate, adding to the initial setup complexity and cost compared to standalone electric or gas water heaters.
The Triangle Tube SMART40 Phase III is an exceptional choice for homeowners seeking an efficient and abundant supply of domestic hot water. Its innovative design and robust construction make it an ideal solution for households that prioritize energy savings and long-term reliability from their water heating systems.
9. Westinghouse Tankless Water Heater Electric 14kW 240V, Instant On-Demand Hot
Experience endless, on-demand hot water with the Westinghouse Electric Tankless Water Heater. This compact, 14kW 240V unit delivers instant hot water precisely when you need it, eliminating cold showers and long waits, perfect for modern, efficient homes seeking continuous hot water supply.
Boasting up to 38 GPM with a starting flow rate of just 5 GPM, this tankless electric heater provides ample hot water for simultaneous use, like a shower and sink.
5 GPM, this tankless electric heater provides ample hot water for simultaneous use, like a shower and sink. Its smart Wi-Fi connectivity with Alexa and Google Home integration allows effortless temperature control and monitoring, making it a truly smart home solution with robust, ETL-certified safety features.
Pros
- Instant & Continuous Hot Water: Enjoy a steady stream of hot water up to 3.38 GPM, eliminating the risk of running out, ideal for multi-user households and busy mornings.
- Smart Home Integration: Seamlessly control and monitor your hot water settings via Wi-Fi with Alexa and Google Assistant voice commands or through a dedicated app for ultimate convenience.
- Space-Saving & Compact: The sleek, wall-mounted design occupies minimal space, making it an excellent choice for apartments, small homes, or utility rooms where floor space is at a premium.
- Enhanced Safety Features: Multiple layers of protection, including leakage, overheat, dry-fire, and high voltage safeguards, plus an IPX4 water-resistant rating, ensure safe and reliable operation.
- Durable & Low Maintenance: The separate water-electricity pathway minimizes corrosion and scaling, extending the unit’s lifespan and reducing the need for frequent maintenance.
Cons
- Electrical Requirements: Requires dedicated 240V power with a 60-amp double-pole breaker and 6 AWG wiring, which may necessitate professional electrical work if not already configured.
The Westinghouse 14kW 240V electric tankless water heater offers an efficient and convenient solution for consistent hot water needs. Perfect for apartments, cabins, or any home seeking an upgrade to on-demand heating, this unit combines advanced technology with a user-friendly experience for reliable, space-saving hot water.
10. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Experience endless hot water with the Rheem RTG-70XLN-3, a high-efficiency, non-condensing outdoor tankless natural gas water heater. This unit is engineered to meet the demands of modern households with its swift 0 GPM flow rate, ensuring you never run out of hot water for multiple appliances simultaneously.
Its compact, space-saving design and durable construction make it an exceptional choice for delivering reliable on-demand hot water.
Powered by natural gas with a robust 160,000 BTU output, the Rheem RTG-70XLN-3 provides continuous hot water for homes with 2-3 bathrooms, effortlessly handling showers, laundry, and dishwashing. Designed for efficient outdoor installation, its durable metal cabinet and straightforward wall-mounting capability (by a qualified installer) integrate seamlessly into your home’s infrastructure.
Pros
- Delivers an impressive 7.0 gallons per minute (GPM) of continuous hot water, ideal for simultaneous use in multi-bathroom homes and heavy demand scenarios.
- Features hot-start programming to prevent dreaded cold water sandwiches, ensuring a consistent and comfortable hot water experience from the first drop.
- Outdoor-rated design with a durable metal cabinet offers a space-saving solution and simplifies installation, keeping valuable indoor space free.
- Enabled by natural gas and boasting 160,000 BTUs, it provides powerful and efficient heating for reliable on-demand hot water supply.
- Equipped with self-diagnostic programming, freeze protection, and a low activation flow rate for enhanced performance and longevity.
Cons
- Requires professional installation by a qualified technician for safe and optimal operation, which adds to the initial setup cost.
The Rheem RTG-70XLN-3 represents an excellent investment for homeowners seeking an efficient and dependable tankless water heater. Its high flow rate, advanced features, and durable outdoor design make it a perfect fit for busy households that require a constant supply of hot water.
How to Choose the Best Indirect Hot Water Heater
Tank capacity and household needs
The volume of your indirect water heater is a primary determinant of its ability to meet your daily hot water demands.
Selecting the correct tank size ensures you have an ample supply of hot water for all your needs without running out, thereby preventing frustration and inconvenience. A single individual may find a smaller capacity sufficient, while a household with multiple occupants, frequent appliance use, and simultaneous hot water activities like showering and laundry will require a substantially larger reserve.
Material and durability factors
The tank’s construction and insulation are paramount to ensuring reliable, long-term performance from your heating system.
Opting for materials with superior corrosion resistance directly translates to a longer operational lifespan and fewer premature failures. For instance, stainless steel tanks are inherently resistant to rust and galvanic corrosion, offering excellent longevity even in challenging water conditions. Conversely, glasslined steel tanks provide a robust barrier against corrosive elements, though their durability can depend on the integrity of the glass lining over time.
Understanding these differences is key to preventing costly repairs down the line.
Beyond the tank material itself, the quality of insulation plays a critical role in energy efficiency. High-density foam or other effective insulating materials minimize standby heat loss, meaning more of the energy consumed is used to heat your water, not dissipate into the surrounding environment. This not only reduces utility bills but also ensures a consistent supply of hot water when you need it.
Consider how well-insulated the unit is, as this directly impacts its ability to retain heat and your overall operational expenses.
Heating performance and efficiency
The ability of a water heating system to deliver hot water rapidly and consistently is paramount to user satisfaction.
This directly influences your comfort and the system’s overall cost-effectiveness. Units with higher recovery rates can replenish their hot water supply faster, meaning you’re less likely to run out during peak usage times, such as when multiple showers are in use or laundry cycles are running. Similarly, a higher GPM (gallons per minute) output ensures that the flow of hot water from your taps remains strong and steady, preventing a disappointing reduction in pressure.
These factors are crucial for ensuring immediate availability of heated water.
Beyond immediate delivery, evaluating a system’s energy efficiency ratings is vital for long-term financial and environmental benefits. Look for Energy Factor (EF) or Uniform Energy Factor (UEF) ratings, as higher scores indicate less energy consumption and reduced utility bills.
Ensure the indirect tank is compatible with your current boiler or heat source to maximize heat transfer and prevent undue strain on your primary heating equipment, which ultimately contributes to lower operational expenses and a more sustainable setup.
Installation and maintenance considerations
Proper installation and straightforward upkeep are paramount for the longevity and efficient operation of your home’s water heating system.
Opting for a model that necessitates professional installation can add to the initial cost, but often ensures safe and compliant integration with your existing plumbing and boiler. Beyond the initial setup, consider how easily the unit can be accessed for routine maintenance.
Neglecting these simple yet important maintenance procedures can lead to premature component failure, decreased hot water output, and ultimately, a shortened lifespan for your investment.
Look for designs that facilitate these essential tasks, with readily accessible drain valves, accessible ports for rod replacement, and adequate clearance for inspection. This foresight will save you considerable time, expense, and frustration down the line, ensuring a consistent and reliable supply of hot water for your household needs.
Quick Best Indirect Hot Water Heater Buying Checklist
- Understand Your Hot Water Needs Determine how much hot water your household uses daily.
- Evaluate Tank Size Options Choose a capacity that matches your usage without significant over or undersizing.
- Check Material of Construction Opt for durable materials like stainless steel for longevity.
- Assess Heating Power Ensure the unit can meet your demand for hot water recovery.
- Review Energy Efficiency Ratings Look for models that minimize energy consumption.
- Consider Installation and Maintenance Factor in the complexity and upkeep required.
Frequently Asked Questions
What Is An Indirect Hot Water Heater?
An indirect hot water heater uses your home’s boiler to heat water stored in its own tank, offering efficient and on-demand hot water.
How Much Larger Should An Indirect Water Heater Be Than My Current One?
It depends on your usage, but often a slightly larger tank ensures you don’t run out during peak demand.
Are Indirect Hot Water Heaters More Efficient Than Traditional Tanks?
Yes, they leverage your existing boiler, leading to higher energy efficiency compared to standalone electric or gas units.
What Maintenance Do Indirect Hot Water Heaters Require?
Regular checks of the anode rod, flushing sediment, and ensuring proper boiler operation are key maintenance tasks.
Can I Connect An Indirect Hot Water Heater To Any Boiler?
Generally, yes, but compatibility should be confirmed with your boiler’s specifications and the indirect water heater manufacturer.
Final Words
Selecting the best indirect hot water heater ensures a reliable and efficient supply of hot water for your home. By considering capacity, material, and performance, you invest in a system that offers both comfort and potential energy savings.
