15 Best Tankless Water Heaters Under $1000, Compared
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Finding the best tankless water heaters under $1000 requires matching specs to your home’s infrastructure. We compared 15 models using only published listing data. The Stiebel Eltron Tempra 29 Plus leads because its 28.8 kW output handles high demand for homes with 200 amp electrical service. This guide helps you decide which unit fits your fuel type, flow needs, and installation space. You will see how voltage, GPM, and BTU ratings determine performance for your specific setup.
Our top pick: Stiebel Eltron Tempra 29 Plus 28.8kW Tankless.
Quick picks
The best fit for you
- You have 200 amp electrical service Stiebel Eltron Tempra 29 Plus 28.8kW Tankless The 240V 8 kW electric unit fits homes with robust electrical infrastructure.
- You need outdoor propane with high flow Rinnai 6.1 GPM Outdoor Propane Water Heater This 6.6 GPM propane heater suits outdoor users needing high volume and durability.
- You want whole-home natural gas flow Rheem RTG 8.4 GPM Indoor Natural Gas Water Heater The 8.4 GPM indoor natural gas unit provides reliable whole-house heating.
- You need app control for gas heating Westinghouse 7.9 GPM Natural Gas Tankless Water Heater This 7.9 GPM gas heater offers strong capacity and smart app features.
- You need hot water in an RV FOGATTI InstaShower Ultra RV Tankless Water Heater The 3.9 GPM RV unit with mixing tank provides comfort in tight spaces.
Our 15 picks
Stiebel Eltron Tempra 29 Plus 28.8kW Tankless
Best for: homes with 200 amp electrical service
- Fuel Type
- Electric
- Wattage
- 28.8 kW
- Voltage
- 208 V, 240 V
- Dimensions
- 14.5 x 16.6 x 4.63 in
- Use
- Whole House
- Weight
- 19 pounds
View on Amazon: Stiebel Eltron Tempra 29 Plus 28.8kW Tankless
The Stiebel Eltron Tempra 29 Plus is a 28.8 kW electric tankless water heater designed for continuous hot water. It operates on 240 V power and features two temperature memory presets for easy adjustment. This unit requires hard-wired installation with three dedicated 40 amp breakers. Its compact dimensions save space without needing venting. It suits homes with adequate electrical service seeking reliable on-demand heating.
Pros
- 28.8 kW power output for continuous hot water
- Two temperature memory presets for personalized settings
- Compact 14.5 x 16.6 x 4.63 inch design
- No venting required for indoor installation
Cons
- Requires three dedicated 40 amp breakers
- Needs 200 amp total electrical service
- Only includes two temperature presets
Good fit if
- You have a 200 amp electrical panel
- You need a compact indoor unit
- You prefer preset temperature controls
Skip if
- You only have 100 amp service
- You need gas fuel type
- You want smart WiFi connectivity
Verdict: Stiebel Eltron Tempra 29 Plus Electric delivers strong electric heating for homes with robust electrical infrastructure. It fits buyers who value space-saving design and straightforward preset controls over smart features.
Rinnai 6.1 GPM Outdoor Propane Water Heater
Best for: outdoor propane users needing high flow
- Fuel Type
- Propane
- Flow Rate
- 6.1 GPM
- BTU
- 160k BTU
- Installation Location
- Outdoor
- Dimensions
- 24.6 x 14.1 x 10.8 in
- Venting Type
- Non-Condensing
The Rinnai RE160eP is a compact, non-condensing propane tankless water heater designed for outdoor installation. It delivers up to 6.6 GPM of hot water, supporting up to five fixtures simultaneously. Measuring 24.6 x 14.1 x 10.8 inches, it fits in tight spaces. The unit includes an LED screen for error codes and service reminders. It offers a 15-year heat exchanger warranty, making it a durable option for outdoor residential use.
Pros
- 6.6 GPM flow rate supports five fixtures
- Compact outdoor design fits small spaces
- LED screen displays error codes and reminders
- 15-year limited heat exchanger warranty
Cons
- Outdoor installation only
- WiFi control module sold separately
- Propane fuel type limits indoor use
Good fit if
- You need a reliable outdoor propane heater
- You require high flow for multiple fixtures
- You want a compact unit for tight spaces
Skip if
- You need indoor installation capability
- You prefer natural gas over propane
- You want built-in WiFi connectivity
Verdict: Rinnai RE160eP 6.6 GPM Propane Outdoor Heater is a solid choice for homeowners needing high-volume hot water outdoors. It suits those who prioritize durability and flow rate over smart features.
Rheem RTG 8.4 GPM Indoor Natural Gas Water Heater
Best for: Large families with natural gas
- Fuel Type
- Natural Gas
- Flow Rate
- 8.4 GPM
- BTU
- 180,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 8.4 GPM Indoor Natural Gas Water Heater
This Rheem unit delivers 8.4 GPM of hot water using 180,000 BTUs of natural gas. It features a non-condensing design for indoor installation and includes a digital LED panel for ±1°F temperature precision. The 0.82 UEF rating helps reduce energy costs compared to traditional tank heaters. Its compact wall-mount size saves floor space while supporting three to four simultaneous showers for large households.
Pros
- 8.4 GPM flow rate for whole-house use
- 180,000 BTU/hr output capacity
- ±1°F digital temperature control precision
- 0.82 Uniform Energy Factor rating
- Built-in freeze and flame failure protection
Cons
- Indoor installation only requires professional setup
- Non-condensing design may be less efficient than condensing models
- Heavier at 46.5 pounds than some competitors
Good fit if
- You need hot water for 3-4 simultaneous showers
- You have a natural gas supply line
- You want precise temperature control
Skip if
- You require outdoor installation
- You only have propane fuel
- You need WiFi connectivity
Verdict: Rheem RTG 8.4 GPM Natural Gas suits large families needing high flow rates. It provides reliable whole-house heating with precise temperature control for multi-bathroom homes.
Westinghouse 7.9 GPM Natural Gas Tankless Water Heater
Best for: Whole-home hot water with app control
- Fuel Type
- Natural Gas
- Flow Rate
- 7.9 GPM
- BTU
- 180,000 BTU
- Installation Location
- Indoor
- Voltage
- 120 V AC
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: Westinghouse 7.9 GPM Natural Gas Tankless Water Heater
This Westinghouse indoor natural gas unit delivers 7.9 GPM at 180,000 BTU. It features smart WiFi app control and voice commands for remote adjustments. The self-modulating technology maintains temperature stability within ±1°F. It activates at low flow rates of 0.53 GPM and 15 PSI. You get a 2-year unit warranty and 5-year heat exchanger coverage. It suits homes needing whole-house capacity with digital convenience.
Pros
- 7.9 GPM flow rate for multiple simultaneous uses
- 180,000 BTU heating capacity
- Built-in WiFi and voice control
- ±1°F temperature stability
- Activates at 0.53 GPM and 15 PSI
Cons
- Only 2-year limited warranty on the complete unit
- Indoor installation only
- Requires 120V AC power connection
Good fit if
- You need high flow for whole-home use
- You want remote app control
- You have low water pressure
Skip if
- You need outdoor installation
- You require propane fuel
- You want a longer standard warranty
Verdict: Westinghouse APOLO-180K 7.9 GPM Gas Heater offers strong whole-home capacity and smart features for users who prioritize digital control and low-pressure performance.
Rheem RTG 8.4 GPM Outdoor Natural Gas Tankless Heater
Best for: large families with outdoor installation space
- Fuel Type
- Natural Gas
- Flow Rate
- 8.4 GPM
- BTU
- 180,000 BTU/hr
- Installation Location
- Outdoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 8.4 GPM Outdoor Natural Gas Tankless Heater
The Rheem RTG-84XLN delivers 8.4 GPM of hot water at a 35°F rise, powered by 180,000 BTUs of natural gas. This non-condensing unit features a 0.82 UEF rating and precise ±1°F digital temperature control. It is built for outdoor installation with a durable metal cabinet. The design suits whole-house needs for large families with multiple bathrooms, ensuring consistent flow without running out of hot water.
Pros
- 8.4 GPM flow rate supports 3-4 simultaneous showers
- 180,000 BTU/hr output for high demand
- 0.82 UEF efficiency rating
- ±1°F digital temperature precision
- 15-year heat exchanger warranty
Cons
- Outdoor installation only
- No WiFi connectivity in this specific model
- Professional installation required
Good fit if
- You need high flow for multiple bathrooms
- You have an outdoor space for mounting
- You want precise temperature control
Skip if
- You require indoor installation
- You need WiFi smart features
- You have low gas pressure
Verdict: Rheem RTG-84XLN 8.4 GPM Natural Gas is a robust outdoor unit for large households needing high capacity. It fits buyers who prioritize flow rate and precision over smart connectivity.
Rheem RTG 8.4 GPM Outdoor Propane Tankless Water Heater
Best for: Outdoor whole-house propane setups
- Fuel Type
- Liquid Propane
- Flow Rate
- 8.4 GPM at 35°F rise
- BTU
- 180,000 BTU/hr
- Installation Location
- Outdoor
- Temperature Control
- Digital LED, ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 8.4 GPM Outdoor Propane Tankless Water Heater
This Rheem unit delivers 8.4 GPM at a 35°F rise using liquid propane. It produces 180,000 BTUs of heat for whole-house use. The outdoor design removes the need for venting. Digital controls adjust temperature within ±1°F. It suits large families needing multiple simultaneous showers. The metal cabinet is built for exterior mounting.
Pros
- 8.4 GPM flow rate for 3-4 showers
- 180,000 BTU/hr output
- No venting required for outdoor install
- ±1°F digital temperature precision
- 0.82 Uniform Energy Factor
Cons
- Outdoor installation only
- No WiFi connectivity on this specific model
- Requires professional installation
Good fit if
- You need hot water for 3-4 bathrooms
- You prefer outdoor installation to avoid venting
- You use liquid propane fuel
Skip if
- You require indoor installation
- You use natural gas instead of propane
- You need remote WiFi monitoring
Verdict: Rheem RTG 8.4 GPM Outdoor Propane handles high demand for large homes. It fits buyers who want outdoor simplicity and strong flow rates without venting complexity.
Rinnai 7.5 GPM Outdoor Propane Tankless Water Heater
Best for: Outdoor propane homes needing high flow
- Fuel Type
- Propane
- Flow Rate
- 7.5 GPM
- Installation Location
- Outdoor
- Dimensions
- 35 x 14.5 x 22 inches
- Weight
- 63 pounds
View on Amazon: Rinnai 7.5 GPM Outdoor Propane Tankless Water Heater
The Rinnai RUS75eP is an outdoor propane tankless water heater delivering 7.5 GPM. It heats water on demand, saving space and energy. The unit measures 35 by 14.5 by 22 inches and weighs 63 pounds. It supports multiple venting options for flexible placement. This model is designed for outdoor installation only. It provides consistent hot water for up to six appliances simultaneously.
Pros
- 7.5 GPM flow rate for high demand
- Propane fuel type for off-grid use
- Outdoor installation design
- Compact 35 by 14.5 by 22 inch footprint
Cons
- Outdoor installation only
- Propane fuel requires tank supply
- Professional installation recommended
Good fit if
- You need high flow rate for multiple bathrooms
- You have outdoor space for installation
- You use propane as your primary fuel
Skip if
- You require indoor installation
- You use natural gas only
- You need a compact RV unit
Verdict: Rinnai RUS75eP 7.5 GPM Propane delivers strong 7.5 GPM output for homes needing high hot water volume. It suits outdoor propane setups where space is limited and high flow is essential.
FOGATTI InstaShower Ultra RV Tankless Water Heater
Best for: RV shower and kitchen replacement
- Flow Rate
- 3.9 GPM
- BTU
- 66,000 BTU
- Temperature Control
- ±1°F
- Certification
- CSA
- Dimensions
- 15 x 15 x 15 in
- Use
- RV
View on Amazon: FOGATTI InstaShower Ultra RV Tankless Water Heater
This unit delivers 66,000 BTU with a flow rate of up to 3.9 GPM. It features a built-in mixing tank for stable temperatures within ±1°F. The compact 15-inch cube design replaces standard RV tank heaters. It includes a remote controller and operates at altitudes up to 9,800 feet. You get hot water efficiently in mobile living spaces.
Pros
- 66,000 BTU heating capacity
- Up to 3.9 GPM flow rate
- Built-in mixing tank for temperature stability
- Includes intelligent remote controller
- CSA certified for safety
Cons
- Lower flow rate than whole-house models
- Compact 15-inch cube limits installation options
- No smart app connectivity listed
Good fit if
- You need a direct replacement for Suburban or Atwood tank heaters
- You want precise temperature control within ±1°F
- You install in high-altitude RVs up to 9,800 feet
Skip if
- You require simultaneous hot water for multiple full showers
- You need a whole-house unit for a permanent home
- You prefer a larger 18-inch installation footprint
Verdict: FOGATTI InstaShower Ultra RV suits travelers who need reliable hot water in tight spaces. Its 3.9 GPM flow and mixing tank provide comfort for single users or couples in an RV.
Rheem RTG Series 7.0 GPM Propane Tankless Water Heater
Best for: Indoor propane homes needing precise temp control
- Fuel Type
- Liquid Propane
- Flow Rate
- 7.0 GPM
- BTU
- 160,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG Series 7.0 GPM Propane Tankless Water Heater
This indoor liquid propane unit delivers 7.0 GPM at a 35°F rise, powered by 160,000 BTUs. It features a non-condensing design with an 0.82 UEF for efficiency. The digital LED panel allows ±1°F adjustments, and built-in freeze protection adds safety. It suits homes needing reliable whole-house hot water without tank bulk.
Pros
- 7.0 GPM flow rate supports 2-3 simultaneous showers
- 160,000 BTU/hr output for high performance
- ±1°F precision digital temperature control
- 0.82 UEF energy efficiency rating
- Built-in freeze and flame failure protection
Cons
- No WiFi connectivity in this 7.0 GPM model
- Indoor installation only requires professional setup
- Heavier at 46.5 pounds than compact units
Good fit if
- You need a whole-house propane solution for 2-3 bathrooms
- You prefer precise ±1°F temperature adjustments
- You have space for an indoor wall-mount unit
Skip if
- You require outdoor installation capabilities
- You want smart WiFi remote control features
- You need more than 7.0 GPM flow rate
Verdict: Rheem RTG-70DVLP-3 7.0 GPM Propane is a solid choice for indoor propane users who value precise temperature control and high efficiency over smart connectivity.
Rinnai Smart-Circ 6.1 GPM Natural Gas Heater
Best for: Indoor homes needing built-in recirculation
- Fuel Type
- Natural Gas
- Flow Rate
- 6.6 GPM
- Installation Location
- Indoor
- Dimensions
- 27.3 x 14.1 x 10.8 inches
- Weight
- 51 pounds
View on Amazon: Rinnai Smart-Circ 6.1 GPM Natural Gas Heater
The Rinnai REP160iN is an indoor natural gas unit delivering 6.1 to 6.6 GPM. It features Smart-Circ technology with a built-in recirculation pump that learns your usage patterns. This compact design fits tight spaces while supporting up to five simultaneous fixtures. It includes a 15-year heat exchanger warranty. You should choose this if you want integrated recirculation without extra hardware.
Pros
- Built-in Smart-Circ recirculation pump
- 6.1 to 6.6 GPM flow rate
- Compact 27.3 x 14.1 x 10.8 inch size
- 15-year heat exchanger warranty
Cons
- WiFi control requires separate Controlr module
- Lower flow rate than 8.4 GPM competitors
- Indoor installation only
Good fit if
- You want built-in recirculation
- You need a compact indoor unit
- You prefer natural gas fuel
Skip if
- You need outdoor installation
- You require 8.4 GPM flow
- You want included WiFi control
Verdict: The Rinnai REP160iN Natural Gas Smart-Circ suits households needing reliable indoor hot water with integrated recirculation. It is ideal for homes where space is limited and you want to avoid purchasing a separate pump.
A. O. Smith ProLine XE Outdoor Natural Gas Heater
Best for: Outdoor single-bathroom setups
- Fuel Type
- Natural Gas
- Flow Rate
- 6.6 GPM
- BTU
- 120,000 BTU/hr
- Installation Location
- Outdoor
- Dimensions
- 22.9 x 13.9 x 13.9 inches
- Weight
- 50 pounds
View on Amazon: A. O. Smith ProLine XE Outdoor Natural Gas Heater
This A. O. Smith unit delivers 6.6 GPM at 120,000 BTU for outdoor natural gas use. Its compact 22.9 x 13.9 x 13.9 inch frame saves space. The copper heat exchanger stabilizes water temperature quickly. You get flexible venting up to 100 feet with 4-inch PVC. It includes integrated controls for easy troubleshooting.
Pros
- 6.6 GPM flow rate for steady hot water
- Commercial-grade copper heat exchanger for fast heat transfer
- Compact wall-mount design measuring 22.9 x 13.9 x 13.9 inches
- Flexible venting options up to 100 feet with 4-inch PVC
Cons
- Lower flow rate compared to 8.4 GPM competitors
- Outdoor-only installation limits placement options
- Heavier build at 50 pounds
Good fit if
- You need an outdoor unit for a single bathroom
- You want a compact heater with flexible venting
- You prefer copper heat exchangers for durability
Skip if
- You require indoor installation only
- You need more than 6.6 GPM flow
- You want a propane fuel type
Verdict: A. O. Smith 6.6 GPM Outdoor Gas Heater suits outdoor setups where space is tight and venting flexibility matters. It fits single-bathroom homes that do not need high-flow capacity.
Marey GA24CSALP 7.5 GPM Propane Heater
Best for: Indoor propane homes needing high flow
- Fuel Type
- Liquid Propane
- Flow Rate
- 7.5 GPM
- BTU
- 170,000 BTU
- Installation Location
- Indoor
- Certification
- CSA
- Dimensions
- 26.2 x 17.1 x 7.3 inches
This indoor unit delivers 7.5 GPM at 170,000 BTU using liquid propane. The compact 26.2-inch height fits standard spaces. CSA certification ensures safety with overheat and anti-freeze protection. You get unlimited hot water for multiple use points. The dynamic power display lets you adjust output. It suits households needing reliable indoor propane heating without complex venting.
Pros
- High 170,000 BTU output for strong performance
- 7.5 GPM flow rate supports multiple fixtures
- CSA certified for safety in USA and Canada
- Compact 7.3-inch depth saves wall space
- Dynamic power adjustment via user-friendly display
Cons
- Limited to indoor installation only
- Not recommended for elevations above 2,000 ft
- Requires professional installation for safety compliance
Good fit if
- You need a high-flow indoor propane heater
- You have standard 3-inch exhaust venting available
- You live below 2,000 ft elevation
Skip if
- You require outdoor installation capability
- You live above 2,000 ft elevation
- You prefer natural gas over propane
Verdict: Marey 7.5 GPM Propane Tankless Heater offers strong indoor performance with CSA safety. It fits homes needing high flow from propane without outdoor mounting needs.
MIZUDO 7.9 GPM Indoor Propane Tankless Heater with WiFi
Best for: Indoor multi-bathroom propane setups
- Fuel Type
- Propane
- Flow Rate
- 7.9 GPM
- BTU
- 180,000 BTU/h
- Installation Location
- Indoor
- Voltage
- 120V AC
- Temperature Control
- ±1°F
View on Amazon: MIZUDO 7.9 GPM Indoor Propane Tankless Heater with WiFi
This indoor propane unit delivers 7.9 GPM at 180,000 BTU. It uses a 120V AC power supply and a sealed combustion system. The self-modulating control keeps temperature stable within ±1°F. WiFi app support allows remote adjustments. It suits larger households needing steady hot water across multiple fixtures.
Pros
- 7.9 GPM flow rate for high demand
- 180,000 BTU input capacity
- WiFi app control for remote monitoring
- Temperature stability within ±1°F
Cons
- Indoor installation only
- Propane fuel type limits placement
- 2-year unit warranty is shorter than industry standard
Good fit if
- You need high flow for multiple bathrooms
- You want remote temperature control via app
- You have an indoor propane supply
Skip if
- You require outdoor installation
- You use natural gas only
- You need a longer warranty period
Verdict: MIZUDO 7.9 GPM Propane Indoor Heater provides strong flow and precise temperature control for busy indoor homes. It fits households that value app management and have propane access.
Whale 3-Gallon 12V Electric Water Heater
Best for: Boats and RVs with 12 V power
- Wattage
- 300 W
- Capacity
- 3 gallons
- Voltage
- 12V DC
- Dimensions
- 13-1/2 W x 14-1/2 D x 13-1/4 H inches
- Fuel Type
- Electric
This compact unit heats water using 12 V DC power, making it ideal for boats and RVs where shore power is unavailable. The 300 W element maintains hot water for up to 10 hours in its 3-gallon tank. Its small footprint allows installation in tight spaces like under seating or in the galley. It includes an integrated temperature and pressure relief valve for safety. This model suits users needing efficient, low-power heating in confined areas.
Pros
- Runs on 12 V DC without a generator or inverter
- 300 W element heats water efficiently
- Compact dimensions fit under seating or in galleys
- Integrated temperature and pressure relief valve included
Cons
- Small 3-gallon capacity limits continuous hot water supply
- Low 300 W power output heats water slowly
- No WiFi or smart control features listed
Good fit if
- You need a 12 V DC heater for a boat or RV
- You have limited space for installation
- You want a simple, non-electric grid-dependent unit
Skip if
- You require high flow rates for multiple fixtures
- You need a large tank for extended hot water use
- You want smart home integration or remote control
Verdict: Whale S360EW 3-Gallon 12V Water Heater is a practical solution for small vessels or campers with 12 V power. It fits users who prioritize space savings and off-grid capability over high volume or smart features.
Stiebel Eltron Tempra 36 Trend Electric
Best for: homes with 300 A electrical service
- Fuel Type
- Electric
- Wattage
- 36 kW
- Voltage
- 240 V
- Temperature Control
- 68° to 140°F
The Stiebel Eltron Tempra 36 Trend is a 36 kW electric tankless water heater designed for continuous hot water. It operates on 240 V power and reaches output temperatures between 68°F and 140°F. This unit requires a minimum 300 A electric service. Its compact white design saves space and needs no venting. It suits homes with strong electrical infrastructure seeking on-demand heating.
Pros
- 36 kW heating power for continuous flow
- Digital temperature display for precise control
- No venting required for easy installation
- Solid copper heating system for durability
Cons
- Requires a minimum 300 A electric service
- Limited to electric fuel type only
- Temperature range caps at 140°F
Good fit if
- You have a 300 A electrical service
- You need a vent-free indoor unit
- You want precise digital temperature control
Skip if
- You only have a 200 A service
- You need a gas-powered unit
- You require outdoor installation
Verdict: Stiebel Eltron Tempra 36 Trend Electric Heater delivers reliable on-demand heat for homes with robust electrical systems. It fits users who prioritize vent-free installation and precise digital temperature management.
Specifications side by side
| Spec | Stiebel Eltron Tempra 29 Plus 28.8kW Tankless | Rinnai 6.1 GPM Outdoor Propane Water Heater | Rheem RTG 8.4 GPM Indoor Natural Gas Water Heater | Westinghouse 7.9 GPM Natural Gas Tankless Water Heater | Rheem RTG 8.4 GPM Outdoor Natural Gas Tankless Heater | Rheem RTG 8.4 GPM Outdoor Propane Tankless Water Heater | Rinnai 7.5 GPM Outdoor Propane Tankless Water Heater | FOGATTI InstaShower Ultra RV Tankless Water Heater | Rheem RTG Series 7.0 GPM Propane Tankless Water Heater | Rinnai Smart-Circ 6.1 GPM Natural Gas Heater | A. O. Smith ProLine XE Outdoor Natural Gas Heater | Marey GA24CSALP 7.5 GPM Propane Heater | MIZUDO 7.9 GPM Indoor Propane Tankless Heater with WiFi | Whale 3-Gallon 12V Electric Water Heater | Stiebel Eltron Tempra 36 Trend Electric |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fuel Type | Electric | Propane | Natural Gas | Natural Gas | Natural Gas | Liquid Propane | Propane | not specified | Liquid Propane | Natural Gas | Natural Gas | Liquid Propane | Propane | not specified | Electric |
| Flow Rate | not specified | 6.1 GPM | 8.4 GPM | 7.9 GPM | 8.4 GPM | 8.4 GPM at 35°F rise | 7.5 GPM | 3.9 GPM | 7.0 GPM | 6.6 GPM | 6.6 GPM | 7.5 GPM | 7.9 GPM | not specified | not specified |
| BTU | not specified | 160k BTU | 180,000 BTU/hr | 180,000 BTU | 180,000 BTU/hr | 180,000 BTU/hr | not specified | 66,000 BTU | 160,000 BTU/hr | not specified | 120,000 BTU/hr | 170,000 BTU | 180,000 BTU/h | not specified | not specified |
| Wattage | 28.8 kW | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | 300 W | 36 kW |
| Installation Location | not specified | Outdoor | Indoor | Indoor | Outdoor | Outdoor | Outdoor | not specified | Indoor | Indoor | Outdoor | Indoor | Indoor | not specified | not specified |
| Capacity | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | 3 gallons | not specified |
| Voltage | 208 V, 240 V | not specified | not specified | 120 V AC | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified | 120V AC | 12V DC | 240 V |
| Temperature Control | not specified | not specified | ±1°F | 95°F–149°F, ±1°F | ±1°F | Digital LED, ±1°F | not specified | ±1°F | ±1°F | not specified | not specified | not specified | ±1°F | not specified | 68° to 140°F |
| Certification | not specified | not specified | CSA | CSA | CSA | CSA | not specified | CSA | CSA | not specified | not specified | CSA | CSA | not specified | not specified |
| Dimensions | 14.5 x 16.6 x 4.63 in | 24.6 x 14.1 x 10.8 in | 24.2 x 13.5 x 10.3 inches | 26.2 x 17.1 x 17.1 in | 20.8 x 13.5 x 9.4 inches | 20.8 x 13.5 x 9.4 inches | 35 x 14.5 x 22 inches | 15 x 15 x 15 in | 24.2 x 13.5 x 10.3 inches | 27.3 x 14.1 x 10.8 inches | 22.9 x 13.9 x 13.9 inches | 26.2 x 17.1 x 7.3 inches | 25 x 16.3 x 7.3 in | 13-1/2 W x 14-1/2 D x 13-1/4 H inches | not specified |
| Use | Whole House | not specified | not specified | Whole House | not specified | not specified | not specified | RV | not specified | not specified | not specified | not specified | not specified | not specified | not specified |
| Venting Type | not specified | Non-Condensing | Non-Condensing | not specified | Non-Condensing | Non-Condensing | not specified | not specified | Non-Condensing | not specified | not specified | not specified | not specified | not specified | not specified |
| Features | not specified | not specified | not specified | WiFi | WiFi | WiFi | not specified | not specified | WiFi | not specified | not specified | not specified | WiFi | not specified | not specified |
| Weight | 19 pounds | 49.2 pounds | 46.5 pounds | 39.3 pounds | 39.3 pounds | 39.3 pounds | 63 pounds | not specified | 46.5 pounds | 51 pounds | 50 pounds | 40.8 pounds | 39.6 pounds | not specified | not specified |
| Size | 29 (kW) | 6.6 GPM | 8.4 GPM (Standard) | APOLO-180K | 8.4 GPM (No WiFi) | 8.4 GPM (Non-WiFi) | 7.5 GPM | not specified | 7.0 GPM (No WiFi) | 6.6 GPM | not specified | 24L | Propane Gas, 7.9 GPM, 180,000 BTU, Indoor | One Size | not specified |
| Color | White | Silver | Gray | Grey 79NI | Gray | Gray | Outdoor Installation | IS Ultra, Gray | Gray | Silver | White | White | White 7.9P | White Epoxy | White |
| Model | 239223 | REU-VE2125WD-US-P | RTG-84DVLN-3 | HW180A0G-NG | RTG-84XLN-3 | RTG-84XLP-3 | RUS Series | FS10B1SGD | RTG-70DVLP-3 | REU-VEP2125FFD-US-N | ATO-140H 100 | GA24CSALP | HW180A0W-LP | S360EW | not specified |
Trade-offs in sub-1000 tankless units
Units under this price point cover electric, gas, and propane fuels. Electric models like the Stiebel Eltron Tempra 29 Plus require 240V service and offer preset controls. Gas and propane heaters, such as the Rinnai 6.1 GPM, provide higher flow rates for whole-home use. You may find fewer smart features on premium gas units. Some models lack WiFi connectivity despite high capacity. Outdoor units need proper venting. RV heaters prioritize compact size over high volume.
- Electric models need 240V infrastructure and lack smart controls
- High-flow gas units often omit WiFi connectivity
- RV heaters sacrifice volume for compact dimensions
- Outdoor installations require specific non-condensing venting setups
If you need outdoor heating equipment, compare specifications for the best patio heaters under 1000.
How We Picked These Units
We selected 15 tankless water heaters currently priced under $1000. Our list includes only one size or variant per product family. We pulled all details directly from the specifications and feature lists on the Amazon listings. We never handle the units or test them ourselves. Every spec comes straight from the manufacturer's published data.
We order the products by availability first. Next, we sort by the listing's overall rating weighted by the number of ratings. Finally, we consider how many of our criteria each spec meets. Prices and stock change daily. A product may move in or out of this guide as its price shifts.
How to choose the right one
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Match fuel to your home
Start by confirming your available fuel source. Electric units like the Stiebel Eltron Tempra 29 Plus require a dedicated 240V circuit and high amperage. Gas and propane models, such as the Rheem RTG 8.4 GPM, need a gas line and proper venting. If you lack gas access, electric is your only option. If you have propane, you can choose between indoor or outdoor units. Always verify your current fuel infrastructure before selecting a model to avoid costly retrofitting.
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Check electrical capacity for electric
Electric tankless heaters demand significant power. The Stiebel Eltron Tempra 29 Plus operates at 240V and 8 kW, requiring a robust 200 amp electrical service. The Stiebel Eltron Tempra 36 Trend draws even more power, needing 300 amp service. If your home has standard 100 amp service, these high-output units will trip breakers. Check your main panel capacity before buying. Electric models are compact but place heavy loads on your electrical system. Ensure your wiring and breakers can handle the specified wattage safely.
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Select the right flow rate
Flow rate determines how many fixtures you can use simultaneously. A 6.1 GPM unit, like the Rinnai 6.1 GPM Outdoor Propane, suits small households or single-bathroom setups. Large families may need 8.4 GPM models, such as the Rheem RTG 8.4 GPM Indoor Natural Gas, to run multiple showers. Lower flow rates, like the 3.9 GPM FOGATTI InstaShower Ultra RV, are only suitable for RVs or tiny spaces. Calculate your peak demand. If you need two showers running at once, choose a higher GPM rating to avoid temperature drops.
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Plan for indoor or outdoor use
Your installation location dictates the unit type. Outdoor models, like the Rinnai 6.1 GPM Outdoor Propane, are weather-resistant but need mounting space outside. Indoor units, such as the Rheem RTG 8.4 GPM Indoor Natural Gas, require venting through a wall or roof. Some units, like the MIZUDO 7.9 GPM Indoor Propane, are designed specifically for indoor air quality. If you live in a cold climate, indoor units may perform better in winter. Check local codes for placement restrictions and clearance requirements for your chosen location.
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Consider venting requirements
Gas and propane heaters require venting to expel combustion gases. Most units in this list are non-condensing, which means they use standard venting materials. The Rinnai Smart-Circ 6.1 GPM Natural Gas Heater includes built-in recirculation, reducing the need for extra pumps. Electric models, like the Stiebel Eltron Tempra 29 Plus, need no venting at all. If you lack existing venting paths, electric or outdoor propane units may be easier to install. Always verify venting compatibility with your home’s current setup to ensure safe operation and code compliance.
Frequently asked questions
Can I install a tankless water heater outdoors?
Yes, several models in this list are designed for outdoor use. The Rinnai RE160eP and Rheem RTG-84XLN are built for exterior mounting. These units feature non-condensing venting and weather-resistant builds. You must ensure the location allows for proper clearance and drainage. Indoor units lack these protections and should not be exposed to the elements.
What is the highest flow rate available under $1000?
The Rheem RTG 8.4 GPM series offers the highest flow rate at 8.4 gallons per minute. This capacity suits large families with multiple bathrooms. The Westinghouse APOLO-180K provides a close alternative at 7.9 GPM. Higher flow rates allow simultaneous use of showers and sinks without temperature drops.
Do I need WiFi for a tankless water heater?
WiFi is not required for operation but adds convenience. The Rheem RTG-84XLN and MIZUDO 7.9 GPM models include WiFi for remote control. You can adjust settings via an app if you choose these units. Many other top picks, like the Stiebel Eltron Tempra 29 Plus, use preset controls without connectivity.
Which unit is best for an RV or boat?
The FOGATTI InstaShower Ultra is designed specifically for RVs and boats. It delivers 3.9 GPM with a mixing tank for comfort. The Whale S360EW is another option, using 12V electric power and a 3-gallon tank. These compact units fit tight spaces and off-grid power sources better than whole-home gas models.
Do gas tankless heaters require special venting?
Yes, gas and propane models need proper venting to exhaust combustion gases. Most units here, including the Rinnai and Rheem gas models, use non-condensing venting. This type is simpler to install than condensing systems. You must follow manufacturer guidelines for vent pipe material and length to ensure safe operation.
What electrical service do electric tankless heaters need?
Electric units require significant electrical capacity. The Stiebel Eltron Tempra 29 Plus needs a 200 amp electrical service. It operates on 240V with 8 kW heating elements. The Tempra 36 Trend demands even more power, suited for homes with 300 amp service. You must verify your panel can handle these loads before installation.
Are there indoor propane options available?
Yes, several indoor propane models are available. The Rheem RTG-70DVLP-3 and Marey GA24CSALP are built for indoor installation. They provide high flow rates, up to 7.5 GPM for the Marey. You must ensure adequate ventilation and proper gas line connections. These units offer precise temperature control for indoor comfort.