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If you are tired of waiting for hot water at faucets and showers, a tankless water heater with a recirculating pump can eliminate long cold-water waits while conserving space. These systems deliver near-instant hot water by circulating tempered water back to the heater so supply lines stay warm without running taps for minutes. Choosing the right unit matters because flow capacity, control options, and installation complexity determine whether the system reliably serves multiple fixtures or just a single bath. This guide covers five shortlisted top picks for tankless water heaters equipped with recirculating pumps and explains the evaluation criteria we used. Read on to compare the technical specs, installation considerations, and user experience tradeoffs so you can match a model to your plumbing layout and hot-water demand.
Top Picks at a Glance
| Best Overall The best all-around choice for most situations | Rinnai REP199eN Tankless Water Heater |  |
| Best Quality Built to a higher standard if you want something more solid | A. O. Smith ATI-540P-N Tankless Water Heater |  |
| Best Budget The cheapest option that still gets the job done reliably | APUS Propane Tankless Water Heater |  |
| Top Rated A top-rated pick with lots of positive feedback | Rheem IKONIC RECTGH-SR11iN |  |
| Most Popular A crowd favorite that many people choose with confidence | Rinnai RXP199iN Tankless Water Heater |  |
Rinnai REP199eN Tankless Water Heater
| Power Source | gas_powered |
|---|---|
| Special Features | Smart-Circ Intelligent Recirculation |
| Flow Rate | 7.9 gpm |
| Maximum Temperature | 140 °F |
| Heat Output | 199000 british thermal units |
The Rinnai REP199eN is a non-condensing outdoor tankless natural gas heater that delivers on-demand hot water while taking up minimal wall space. It includes a factory-installed recirculation pump and Smart-Circ technology that learns typical water-use patterns to start circulating hot water on schedule, which shortens wait times at fixtures and can reduce wasted water. With a rated flow around 7.9 gpm and 199k BTU heat output this model can support multiple fixtures at once, making it suitable as a primary home water heater. Installation should be done by a professional because it is gas-powered and intended for outdoor mounting, and WiFi control requires an optional module. The compact, durable housing and long heat-exchanger warranty are practical for homeowners seeking a reliable, space-saving replacement for a tank-style heater, though it is non-condensing so it will not reach the highest possible efficiency of condensing models.
Best for: Homeowners who want a reliable, space-saving primary water heater with a built-in recirculation pump to reduce wait times and water waste while supporting several fixtures.
Less Ideal for: Buyers seeking the absolute highest energy efficiency from a condensing unit or those who need an indoor installation option.
- Built-in recirculation pump with Smart-Circ learning reduces hot-water wait times and water waste
- Compact outdoor design saves indoor space and is easy to site on exterior walls
- 7.9 gpm flow rate and 199,000 BTU output supports multiple fixtures simultaneously
- Long heat exchanger coverage for durability with a 15-year heat exchanger guarantee
- Non-condensing design means lower theoretical efficiency compared with condensing tankless models
- Requires professional gas installation and outdoor venting considerations
- WiFi connectivity requires an optional Controlr module sold separately
Verdict: Choose this Rinnai REP model if you want a compact outdoor gas tankless heater with a factory-installed recirculation pump that minimizes wait time for hot water.
A. O. Smith ATI-540P-N Tankless Water Heater
| Power Source | Natural Gas |
|---|---|
| Flow Rate | 10 gpm |
| Heat Output | 199000 BTU |
| Efficiency | 0.93 UEF |
| Mount Type | Wall |
The ATI-540P-N is a high-capacity, performance-focused tankless water heater built for homes needing steady hot-water demand. It delivers up to 10 gpm and a 199,000 BTU condensing heat output with a reported 0.93 UEF, so it can run multiple fixtures or several bathrooms concurrently in many climates. The unit is wall-mounted and uses natural gas as its power source, and it includes integrated recirculation for near-instant hot water at fixtures when plumbed with the proper bypass. Safety features such as overheat protection, exhaust and water temperature controls, and an air-fuel ratio sensor help maintain reliable operation. Construction uses commercial-grade materials with an alloy steel body and a long heat-exchanger warranty, reflecting its focus on durability. Expect professional installation and possible additional plumbing (bypass) to enable recirculation; the product is sizable and requires appropriate venting and gas connections. For buyers prioritizing sustained flow and factory-integrated recirculation, this model is a practical, high-performance option.
Best for: Buyers who need dependable, high-flow hot water for multiple bathrooms and value integrated recirculation to reduce wait time for hot water.
Less Ideal for: If you have a small household with low simultaneous hot-water demand or limited gas/venting capacity, a lower-capacity or electric unit would be a better fit.
- High continuous flow rate up to 10 gpm suitable for multiple fixtures
- High heat output (199,000 BTU) and condensing design for efficiency
- Integrated recirculation pump provides near-instant hot water when plumbed correctly
- Robust safety controls including overheat protection and AFR sensor
- Commercial-grade construction with a long heat exchanger warranty
- Recirculation function may require an external bypass valve which is not included
- Professional installation and proper venting are necessary, adding to install complexity
- Larger physical size and gas requirements limit DIY installs and some retrofit situations
Verdict: Choose the ATI-540P-N when you want a factory-integrated recirculation tankless heater that delivers high continuous flow and robust performance for multi-bath homes.
APUS Propane Tankless Water Heater
| Power Source | Liquid Propane |
|---|---|
| Flow Rate | 6.8 gpm |
| Maximum Temperature | 140 °F |
| Voltage | 120 volts |
| Special Features | Zero-Cold-Water Technology, WiFi Remote Control, Smart Seasonal Technology, Turbo Flow Mode |
This APUS propane tankless unit is a compact whole-home heater aimed at delivering instant hot water with a powerful 140,000 BTU burner and a built-in booster pump that raises flow to a claimed 6.8 GPM. It is commonly used to feed multiple fixtures simultaneously and supports features you expect for recirculating setups, including zero-cold-water single-circulation technology and a booster pump to reduce lag. Smart conveniences include Wi‑Fi control via the Tuya app, precise temperature adjustment from 95°F to 140°F, and an ECO/Smart Seasonal mode to cut energy use. Practical safety items are well covered with freeze protection, overheat safeguards, and a quieter turbo fan. The trade-offs are typical for budget-focused tankless units: installation requires proper propane and venting for indoor use and occasional draining in freezing conditions, and real-world flow rates depend on incoming water temperature and plumbing layout. For buyers who want instant hot water with remote control and an integrated pump without premium pricing, this model packs a lot of features into a small footprint.
Best for: Buyers looking for a feature-rich, budget-friendly tankless that reduces cold-water wait and supports simultaneous fixtures with an integrated pump and app control.
Less Ideal for: People without access to an indoor propane supply or those who need a plug-and-play electric unit; also not the best choice for installers seeking factory-certified premium commercial equipment.
- Built-in booster pump increases flow to support multiple fixtures
- Zero-cold-water single-circulation tech reduces wait time for hot water
- Wi‑Fi remote control and Smart Seasonal mode for preheating and energy savings
- High heat output (140,000 BTU) suitable for whole-home demand
- Multiple safety protections including freeze and overheat protection
- Requires indoor propane hookup and proper venting, increasing installation complexity
- Freeze protection has limits and unit must be drained if exposed to extended sub-41°F conditions
- Actual GPM will vary with inlet water temperature and household plumbing, so peak flow may be lower than rated
Verdict: If you want instant, whole-home hot water with an integrated recirculating-capable pump and smart control on a budget, this APUS propane tankless delivers strong value.
Rheem IKONIC RECTGH-SR11iN
| Power Source | Natural Gas |
|---|---|
| Flow Rate | 11.2 gpm |
| Maximum Temperature | 140 °F |
| Heat Output | 199900 BTU |
The Rheem IKONIC RECTGH-SR11iN is a condensing tankless natural gas heater designed to deliver continuous hot water for multi-fixture homes while minimizing standby waste. It uses dual heat exchangers and a down-fired pre-mix burner to reach a high output (199,900 BTU) and an 11.2 gpm flow rate, letting several showers and appliances run at once without running cold. A built-in recirculation system and hot-start programming cut wait time at taps and save water, and EcoNet Wi‑Fi lets you monitor usage, run the recirc pump on demand, and receive maintenance alerts from a phone. The unit is compact and wall-mounted for tight installs and supports outdoor conversion with a kit. As a condensing model it achieves high UEF and can qualify for rebates, but installation requires proper venting and a condensate drain and may be more complex than non-condensing units, so plan for professional plumbing and gas service for reliable long-term performance.
Best for: Buyers who prioritize dependable, continuous hot water across multiple bathrooms and want recirculation and smart controls to reduce wait time and water waste.
Less Ideal for: People seeking a minimal DIY install or who cannot accommodate condensate drainage or upgraded gas and venting work should consider simpler non-condensing or point-of-use options.
- High flow capacity (11.2 gpm) suitable for multiple simultaneous fixtures.
- Built-in recirculation reduces wait time and saves water.
- Super high-efficiency condensing design with dual heat exchangers improves energy use and durability.
- EcoNet Wi‑Fi lets you control temperature and recirculation and receive alerts remotely.
- Condensing design requires condensate drain and more complex venting and installation.
- Large BTU input needs correct gas line sizing and professional hookup.
Verdict: Choose this unit if you want a reliable, whole-home tankless system with built-in recirculation and smart Wi‑Fi control for immediate hot water and long-term energy savings.
Rinnai RXP199iN Tankless Water Heater
| Power Source | Natural Gas or Propane |
|---|---|
| Flow Rate | 11 gpm |
| Maximum Temperature | 140 °F |
| Heat Output | 199000 BTU |
| Wattage | 98 watts |
The Rinnai RXP199iN is a compact, condensing tankless water heater designed to deliver continuous hot water for large households while minimizing energy use. It provides up to 11.1 gallons per minute and includes Smart-Circ intelligent recirculation with a built-in pump to shorten hot-water wait times by learning usage patterns and circulating water on a schedule. The unit is convertible between natural gas and propane and can be adapted for indoor or outdoor installs using the Versa Vent, giving installers flexibility. Rinnai highlights a Quick Flush feature for easier maintenance, a user-friendly interface, and very high efficiency (UEF 0.98) that should lower operating costs versus conventional tanks. Real-world trade-offs are typical for high-capacity tankless units: professional installation is recommended, and to access Wi-Fi features you must buy the Control-R module separately. The prodigious heat output and integrated pump make this model a strong choice where fast recovery and minimal hot-water delay matter, but budget for installation and optional accessories when planning a purchase.
Best for: Buyers who prioritize dependable, on-demand hot water for larger households and want a factory-quality unit with an integrated recirculation pump to reduce wait times and save energy.
Less Ideal for: Anyone seeking a DIY install solution or wanting Wi-Fi control out of the box without buying an optional module should consider other options.
- Built-in Smart-Circ recirculation pump reduces wait time for hot water by learning usage patterns
- High flow capacity up to 11.1 GPM supports multiple fixtures simultaneously
- Convertible to natural gas or propane and adaptable for indoor or outdoor venting with Versa Vent
- Very high efficiency (UEF 0.98) for lower energy consumption compared with tank heaters
- Quick Flush design simplifies routine maintenance
- Wi-Fi control requires purchasing the Control-R module separately
- Professional installation is recommended, adding to upfront cost
Verdict: Choose the Rinnai RXP199iN when you need a high-capacity, energy-efficient tankless heater with a built-in recirculation pump to cut wait times and support multiple fixtures.
Choosing the Right Tankless Water Heater with Recirculating Pumps: Key Factors to Consider
Flow Rate Capacity
Flow rate capacity determines how many fixtures a tankless water heater with recirculating pump can serve at once. Match the unit's maximum gallons per minute rating to peak simultaneous demand such as a shower plus a dishwasher. Undersizing leads to temperature drop and poor performance during overlap.
Also consider how the recirculating pump affects usable flow. Some pumps slightly increase head loss in the loop, which can reduce available flow at high-demand moments. Confirm the manufacturer's flow curves and ensure the pump and heater pairing maintains stable outlet temperature at expected loads.
Recirculation Control Options
Control options range from simple timed schedules to demand-activated push-button or motion-sensor triggers. Timed recirculation is easy to implement but can waste energy and water if schedules do not match occupant behavior. Demand-activated systems run the pump only when hot water is needed, saving energy while providing near-instant warmth.
Look for controls that integrate with your home's routine and for units that allow adjustable cycle length, thermostat setpoints, and low-noise pump profiles. Compatibility with dedicated loop sensors or remote call buttons improves convenience in larger homes.
Installation Complexity
Installation complexity affects upfront labor and whether you can retrofit the system without major plumbing work. Hard-piped recirculation loops, dedicated return lines, and crossover valves are more invasive but deliver the best performance. Simpler solutions use existing cold lines and a thermostatic valve to create a pseudo-loop with less disruption.
Assess whether the chosen unit requires electrical upgrades, condensate drainage, or a separate control module. If you plan a retrofit, measure run lengths and note if the unit's pump can overcome your home's plumbing head. Professional installation is often recommended for ensuring safe venting and correct combustion air for gas-fired models.
Energy Use and Operating Cost
A recirculating pump adds electrical consumption, and how often it runs affects operating cost. Demand-activated pumps reduce run time compared to continuous or frequent timed schedules. For gas-fired tankless heaters, consider how modulation behavior pairs with short recirculation runs to avoid excessive cycling.
Look for pumps with variable-speed motors and heaters with modulating burners or variable electrical draw to keep energy use proportional to demand. Efficient control strategy and good insulation of hot lines can noticeably reduce long-term operating costs.
Compatibility With Existing Plumbing
Not every home layout supports a dedicated recirculation loop. Older homes may lack a return line, and adding one can require wall or ceiling access. Consider options that work with an existing cold leg or that use under-sink crossover valves to avoid full re-piping.
Also check fixture placement and run lengths. Long runs increase heat loss and may require a more powerful pump or additional line insulation. Verify whether the unit's warranty or installation guidance places limits on maximum loop length or required pipe diameter.
Maintenance and Serviceability
Regular maintenance keeps tankless systems and recirculation pumps operating smoothly. Descaleable heat exchangers, easy-to-access service panels, and user-replaceable pump cartridges reduce service time and cost. Pumps with clear diagnostic indicators help troubleshoot circulation issues quickly.
Consider local availability of qualified technicians and whether the system allows basic homeowner maintenance tasks such as flushing or filter replacement. Simpler maintenance routines increase long-term reliability and lower total cost of ownership.
How Recirculating Pump Systems Work
A recirculating pump maintains a small loop of warm water between the heater and fixtures so hot water is available immediately when a tap is opened. The pump moves tempered water back to the heater or toward a crossover so cold-water waiting time is minimized. Control logic determines when the pump runs, either on a schedule, on demand, or based on temperature thresholds.
Understanding the loop topology is important. Dedicated return lines deliver the best performance but require additional piping. Alternative approaches reuse the cold line or rely on thermostatic crossover valves to create a temporary return path.
- Dedicated return loop: best performance, more invasive installation
- Cold-leg crossover: lower cost retrofit, somewhat slower recovery
- On-demand activation: lowest run time, needs sensors or buttons
Sizing Your System for Real Household Demand
Start by listing simultaneous fixtures you expect to run, such as two showers and a dishwasher. Add their typical flow rates to estimate peak demand and pick a unit with rated flow that exceeds that number with some margin.
Remember that recirculation contributes to perceived performance even if the heater's peak flow is marginal. A well-designed loop with prompt call response can make a smaller unit feel more capable at delivering hot water quickly to commonly used fixtures.
- Estimate fixture flow rates (gpm) and add them for peak demand
- Allow margin for future fixtures or higher flow heads
- Consider pump head and pipe length when finalizing capacity
Retrofit Vs New Construction Considerations
In new construction, plan for dedicated return piping and place the heater centrally to minimize run lengths. This minimizes pump power needs and reduces heat loss. Include isolation valves and service access near the heater for easier maintenance.
For retrofits, evaluate whether under-sink crossover valves or inline circulators can achieve acceptable performance without tearing out walls. Retrofits often prioritize lower installation cost, but may trade off slightly longer wait times or more frequent pump operation.
- New builds: design dedicated return loops and central heater placement
- Retrofits: consider crossover valves and strategic pump placement
- Always factor in access for maintenance and future service
Control Strategies and Smart Integration
Control strategy has a big influence on comfort and efficiency. Simple timers are inexpensive but may run the pump when no one is home. Demand-based controls triggered by a button, motion sensor, or smartphone app run the pump only when needed and are typically the most energy-efficient.
Some systems integrate with home automation platforms to allow geofencing or remote activation. When evaluating controls, confirm whether the heater and pump communicate directly or require a separate controller. Look for adjustable setpoints and diagnostics that surface call frequency and run time.
- Timer controls: simple but potentially wasteful
- Demand controls: best balance of convenience and efficiency
- Smart integration: useful for remote activation and advanced scheduling
Noise, Vibration, and Placement
Pump noise and vibration can affect comfort when installed near living spaces. Choose pumps with low-noise ratings and plan mounting on solid surfaces with vibration isolation where possible. Insulate pipe runs to reduce water hammer and audible flow sounds.
Also consider whether the heater's fan or combustion components will be audible in nearby rooms. Placement of the unit in utility spaces or outside conditioned areas can help, but factor in additional freezing protection if installed outdoors.
- Use vibration isolators for pump mounts
- Prefer low-noise pumps for near-living-space installs
- Insulate pipes to reduce noise and heat loss
Common Problems and Troubleshooting Tips
Frequent issues include insufficient hot water at remote fixtures, pump cycling too often, and air in the loop. Verify loop routing and valve positions first, then check pump operation and control settings. Air purging and correct pump orientation often resolve weak circulation.
If a heater trips on temperature limits or shows long recovery times, inspect flow rates and scale buildup. Periodic flushing and water treatment reduce scale and extend component life. Keep a service log of call patterns to help technicians diagnose intermittent issues.
- Check valves and loop routing for common flow problems
- Purge air from the loop to restore circulation
- Schedule regular flushing to limit scale formation
How We Chose the Best Tankless Water Heater with Recirculating Pumps
Our editorial process focused on practical, measurable factors that matter when pairing a tankless water heater with a recirculating pump. We prioritized units that demonstrated sufficient continuous flow rate for typical household fixture combinations, reliable pump and control integration for timed or on-demand recirculation, and clear installation pathways for common residential plumbing layouts. Energy efficiency and thermal recovery behavior were assessed through rated energy factors and documented control strategies rather than marketing claims. We also considered build quality indicators such as warranty coverage and corrosion-resistant heat exchanger materials. Excluded from consideration were units that required extensive, specialized remodeling beyond typical retrofit plumbing work or products lacking standard recirculation controls. Our selection favored systems with documented technical specifications and accessible installation documentation. The final list balances hydraulic performance, control flexibility, installation complexity, energy considerations, and long-term durability.
Our full evaluation process is outlined in our review methodology.
FAQ
Will a recirculating pump on a tankless unit increase my energy bills a lot?
It depends on the control strategy. Demand-activated pumps that run only when needed add minimal electricity use. Continuous or frequent timed schedules increase energy consumption. Choosing a variable-speed pump and efficient control minimizes added operating cost.
Can I add a recirculating pump to my existing tankless water heater?
Often you can, but compatibility and ease of installation vary. Some homes need a dedicated return line while others can use a crossover on the cold leg. Check the heater's installation guidelines and consider professional assessment to confirm feasibility.
How do on-demand recirculation controls work with tankless heaters?
On-demand systems trigger the pump via a button, sensor, or app and circulate water until the loop reaches the desired temperature. The heater senses the increased flow and supplies hot water as needed. Proper controls prevent unnecessary pump runtime and reduce cycles.
Does a recirculating pump affect the lifespan of a tankless water heater?
A properly sized and installed pump should not shorten lifespan and can reduce stress by eliminating cold-water slugs. However, poor system design that causes frequent short cycles or incorrect flow profiles can increase wear. Regular maintenance helps preserve longevity.
Are there restrictions on pipe length or loop size for recirculating setups?
Yes, manufacturers often specify maximum loop lengths and recommended pipe diameters because long runs increase head loss and heat loss. Exceeding those limits can reduce performance and may void warranty provisions. Confirm the heater and pump specifications before finalizing layout.
Final Verdict
When choosing a tankless water heater with a recirculating pump, prioritize flow capacity and the control strategy that matches your daily routines. Sizing the unit for peak simultaneous demand, ensuring the pump can overcome plumbing head, and selecting demand-based controls will deliver the best balance of convenience and efficiency. Accept tradeoffs such as modest added electrical use for greatly reduced water waste and faster hot-water delivery. Focus on installation feasibility and maintainability to ensure long-term reliability, and choose the simplest system that satisfies your household's typical hot-water patterns.