Looking Beyond the Reliance Tankless Water Heater X3? 6 Alternatives Worth a Look
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The Reliance Tankless Water Heater X3 delivers 199,000 BTU in a compact 11-inch frame with field-convertible gas options. If you need reliability tankless water heater x3 alternatives, this list covers 6 models that share its core power specs. You might look elsewhere if you require higher flow rates, specific venting types, or smart app controls that the original unit does not prioritize.
We selected these options because their published specifications overlap significantly with the Reliance model. Each alternative matches the 199,000 BTU output while offering different dimensions, flow capacities, or installation flexibility. Some models focus on indoor whole-house performance, while others suit outdoor setups or compact closets. This guide compares them strictly by their technical data to help you find the right fit for your home's hot water demands.
Our top pick: Reliance 199,000 BTU Gas Tankless Water Heater.
Key Differences Between Alternatives
MIZUDO 10.3 GPM Indoor Natural Gas Tankless Water Heater
The MIZUDO unit matches the 199,000 BTU output but adds a 10.3 GPM flow rate, significantly higher than the Reliance X3. It measures 15.9 inches wide and 24.8 inches tall, making it larger than the 11-inch Reliance frame. This model is designed for indoor installation only, whereas the Reliance converts for outdoor use. It includes smart app control for remote monitoring, a feature the Reliance supports via remote but lacks native Wi-Fi. Choose this if you need higher simultaneous fixture flow and digital management in a basement or closet.
Westinghouse 10.3 GPM Natural Gas Tankless Heater
The Westinghouse heater also provides 199,000 BTU and 10.3 GPM, prioritizing high-volume performance over compact sizing. It features built-in Wi-Fi for app-based control, offering more connectivity than the Reliance X3. The unit is rated for indoor use with non-condensing venting, differing from the Reliance’s condensing design. It weighs 56 pounds, which is heavier than the 8.5-pound Reliance. Select this model if you are powering up to seven fixtures simultaneously and prefer smart home integration over a lightweight, convertible unit.
GASLAND Gasmart E 199k BTU Natural Gas
The GASLAND Gasmart E delivers 7.6 GPM with 199,000 BTU, offering lower flow than the 10.3 GPM alternatives but matching the Reliance’s power. It is sized at 14.3 inches wide and 24.7 inches tall, fitting indoor closets similarly to the Reliance. This model is strictly for indoor use, lacking the Reliance’s field-convertible propane capability. It weighs 37.5 pounds, making it heavier than the lightweight Reliance unit. Pick this option if you need a dedicated indoor whole-house heater with solid safety certifications and do not require outdoor installation flexibility.
Camplux Outdoor 8.4 GPM Natural Gas Water Heater
The Camplux WA686M Outdoor model provides 8.4 GPM with 199,000 BTU, designed specifically for outdoor mounting. It measures only 6.5 inches wide, making it narrower than the 11-inch Reliance frame. Unlike the Reliance, which can be converted for indoor use, this unit is fixed for outdoor environments. It weighs 39 pounds, significantly heavier than the Reliance. Choose this heater if you need high flow for outdoor setups without indoor venting constraints and prefer a compact footprint for exterior walls.
Camplux CA686WNG 199k BTU Natural Gas
The Camplux CA686WNG offers 7.6 GPM and 199,000 BTU for indoor whole-house heating. It measures 14.3 inches wide and 7.3 inches deep, providing a different profile than the Reliance X3. This model lacks smart app controls, focusing on straightforward operation and high flow. It weighs 37.5 pounds, which is heavier than the Reliance. Select this unit if you prioritize robust indoor performance and easy maintenance over compact size or digital monitoring features found in other models.
GASLAND Gasmart E 7.6 GPM Natural Gas Heater
The GASLAND Gasmart E 7.6 GPM model provides 199,000 BTU for indoor use. It measures 16.7 inches wide and 11.6 inches tall, offering a different footprint than the Reliance. This unit is designed for compact indoor spaces and lacks the Reliance’s field-convertible propane option. It does not include smart app controls, focusing on core heating performance. Choose this alternative if you need a reliable indoor heater with a square profile and do not require outdoor installation flexibility or high flow rates above 7.6 GPM.
Quick picks
Our 7 picks
Reliance 199,000 BTU Gas Tankless Water Heater
Best for: Compact spaces needing gas flexibility
- Fuel Type
- Natural Gas, Propane
- BTU
- 199,000 BTU
- Installation Location
- Indoor/Outdoor
- Dimensions
- 11 x 11 x 18 inches
- Weight
- 8.5 pounds
View on Amazon: Reliance 199,000 BTU Gas Tankless Water Heater Affiliate link
The Reliance X3 Premium delivers 199,000 BTU of heating power with a compact 11x11x18 inch footprint. It features X3 Scale Prevention Technology to extend heat exchanger life and includes a digital display for dual recirculation scheduling. This unit is field convertible between natural gas and propane, supporting both indoor and outdoor installation with proper venting.
Pros
- 199,000 BTU output for reliable hot water
- X3 Scale Prevention Technology extends heat exchanger life
- Field convertible between natural gas and propane
- Digital display with dual recirculation programming
- Compact 11x11x18 inch dimensions
Cons
- No GPM rating listed in specifications
- Heavier at 8.5 pounds than some competitors
- 15-year heat exchanger warranty is standard, not exceptional
Good fit if
- You need a compact unit for tight indoor or outdoor spaces
- You want the flexibility to switch between gas and propane
- You prefer digital controls for recirculation scheduling
Skip if
- You require a high flow rate above 7.6 GPM
- You need a unit lighter than 8.5 pounds
Verdict: The Reliance X3 Premium 199k BTU suits homeowners needing a compact, convertible heater with scale prevention. It fits well in tight spaces where gas flexibility matters more than high flow rates.
MIZUDO 10.3 GPM Indoor Natural Gas Tankless Water Heater
Best for: Whole-house hot water with smart app control
- Fuel Type
- Natural Gas
- Flow Rate
- 10.3 GPM
- BTU
- 199,000 BTU
- Installation Location
- Indoor
- Voltage
- 120V
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: MIZUDO 10.3 GPM Indoor Natural Gas Tankless Water Heater Affiliate link
The MIZUDO natural gas tankless water heater delivers up to 10.3 GPM with 199,000 BTU of heating input. It features precise temperature control within ±1°F and reaches up to 149°F. The unit includes smart WiFi app control and Alexa compatibility. It is designed for indoor installation with a sealed combustion system. This model suits busy households needing hot water for multiple bathrooms and appliances simultaneously.
Pros
- 10.3 GPM flow rate for whole-house demand
- Precise ±1°F temperature stability
- Smart WiFi app and Alexa control
- Sealed outdoor air combustion system
Cons
- Limited to indoor installation only
- Not recommended for elevations above 3,000 feet
- Standard 2-year full unit warranty
Good fit if
- You need precise temperature control for soaking tubs
- You want app-based monitoring and alerts
- You require high flow for multiple bathrooms
Skip if
- You live at an elevation above 3,000 feet
- You need an outdoor-rated unit
- You prefer propane fuel over natural gas
Verdict: The MIZUDO 10.3 GPM Natural Gas Indoor Heater is a strong choice for homes needing high-volume hot water with smart connectivity. It fits well in closets or basements where indoor venting is available. Buyers prioritizing precise temperature stability and app control will find it suitable.
Westinghouse 10.3 GPM Natural Gas Tankless Heater
Best for: high-demand homes wanting Wi-Fi control
- Fuel Type
- Natural Gas
- Flow Rate
- 10.3 GPM
- BTU
- 199,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- WiFi & APP control
- Venting Type
- Non-Condensing
View on Amazon: Westinghouse 10.3 GPM Natural Gas Tankless Heater Affiliate link
This indoor tankless water heater delivers up to 10.3 GPM using natural gas and a 199,000 BTU burner. It supports up to 7 fixtures simultaneously, making it suitable for large households with high simultaneous hot water demands. You get built-in Wi-Fi and app connectivity for digital temperature control, paired with a standard non-condensing venting setup.
Pros
- 10.3 GPM maximum flow rate
- 199,000 BTU natural gas heating capacity
- Wi-Fi and mobile app temperature control
- Supports up to 7 fixtures
Cons
- Non-condensing venting design
- Indoor installation only
- Unit weight is 56 pounds
Good fit if
- You run up to 7 fixtures simultaneously across a large household.
- You prefer adjusting water temperatures via smartphone app and Wi-Fi.
- You have a dedicated indoor natural gas connection.
Skip if
- You need an outdoor installation setup.
- You require a condensing unit or use liquid propane.
Verdict: Westinghouse 10.3 GPM Smart Tankless Water Heater is built for large homes running up to 7 fixtures simultaneously that need high-output natural gas heating with app-based control.
GASLAND Gasmart E 199k BTU Natural Gas
Best for: small indoor spaces needing high flow
- Fuel Type
- Natural Gas
- Installation Location
- Indoor
- Use
- Whole House
- BTU
- 199,000 BTU
- Dimensions
- 14.3 × 14.3 × 24.7 inches
- Weight
- 37.5 pounds
View on Amazon: GASLAND Gasmart E 199k BTU Natural Gas Affiliate link
The GASLAND Gasmart E delivers up to 7.6 GPM of hot water for whole-house use. It features a 199,000 BTU burner and a compact 14.3 by 24.7-inch footprint. This unit is CSA certified and includes freeze protection. It suits buyers needing reliable indoor heating without taking up much space. The design fits well in closets or laundry rooms.
Pros
- High flow rate of up to 7.6 GPM
- Compact dimensions of 14.3 by 24.7 inches
- CSA certified for safety standards
- Includes freeze protection for year-round use
Cons
- Indoor installation only
- Requires natural gas connection
- Standard 1-year warranty period
Good fit if
- You need a compact unit for small spaces
- You require high flow rates for whole-house use
- You want CSA certified safety features
Skip if
- You need outdoor installation capability
- You require a longer warranty period
- You prefer propane fuel sources
Verdict: GASLAND Gasmart E 7.6 GPM Natural Gas fits homes needing high flow in tight spaces. It offers solid safety certification and compact sizing for indoor closets.
Camplux Outdoor 8.4 GPM Natural Gas Water Heater
Best for: outdoor high-flow needs
- Fuel Type
- Natural Gas
- Flow Rate
- Up to 8.4 GPM
- BTU
- 199,000 BTU
- Installation Location
- Outdoor
- Certification
- CSA
- Dimensions
- 22.2 x 6.5 x 6.5 inches
View on Amazon: Camplux Outdoor 8.4 GPM Natural Gas Water Heater Affiliate link
This outdoor natural gas unit delivers up to 8.4 GPM at 199,000 BTU. It maintains temperature within ±1°F using advanced flow sensors. The compact 22.2-inch design saves space and includes six safety protections like anti-freezing and overheat prevention. You get precise control via a wired remote. It suits households needing high flow for outdoor or utility use.
Pros
- High flow rate of up to 8.4 GPM
- Precise ±1°F temperature stability
- Six-layer safety protection system
- Compact 22.2-inch vertical footprint
Cons
- Outdoor installation only
- Requires wired controller for adjustments
- Heavier at 39 pounds
Good fit if
- You need high flow for multiple outlets
- You have outdoor space for installation
- You want precise temperature control
Skip if
- You require indoor installation
- You prefer wireless remote control
- You have limited vertical space
Verdict: Camplux WA686M Outdoor 8.4 GPM offers strong flow and stability for outdoor setups. It fits homes needing reliable hot water without indoor venting constraints.
Camplux CA686WNG 199k BTU Natural Gas
Best for: High-flow indoor whole-house heating
- Fuel Type
- Natural Gas
- Flow Rate
- 7.6 GPM
- BTU
- 199,000 BTU
- Installation Location
- Indoor
- Voltage
- 120 V
- Certification
- CSA, UL
View on Amazon: Camplux CA686WNG 199k BTU Natural Gas Affiliate link
This Camplux indoor unit delivers up to 7.6 GPM of hot water at 199,000 BTU. It features an oxygen-free copper heat exchanger and bottom-fan technology for safe, quiet operation. The 120V plug and 3/4" NPT connections simplify DIY installation. It includes freeze protection and altitude compensation. This model suits households needing reliable whole-house heating with efficient flame control.
Pros
- Delivers up to 7.6 GPM at 199,000 BTU
- Oxygen-free copper heat exchanger for efficiency
- Bottom-fan technology prevents smoke backflow
- 120V plug and 3/4" NPT connections for easy setup
- Built-in freeze protection with automatic drain assist
Cons
- Requires annual descaling for longevity
- Mandatory winterization below 20°F
- Altitude compensation limited to 2,000 ft
Good fit if
- You need a high-flow indoor unit for multiple bathrooms
- You prefer DIY installation with standard gas connections
- You want quiet operation with bottom-fan technology
Skip if
- You live above 2,000 feet without consulting altitude specs
- You cannot perform annual descaling maintenance
- You need outdoor installation only
Verdict: Camplux CA686WNG 7.6 GPM Natural Gas provides robust indoor heating for busy homes. It fits buyers who prioritize high flow rates and straightforward maintenance over smart features.
GASLAND Gasmart E 7.6 GPM Natural Gas Heater
Best for: Compact indoor whole-house heating
- Fuel Type
- Natural Gas
- Flow Rate
- 7.6 GPM
- BTU
- 199,000 BTU
- Installation Location
- Indoor
- Dimensions
- 16.7 × 16.7 × 11.6 inches
View on Amazon: GASLAND Gasmart E 7.6 GPM Natural Gas Heater Affiliate link
This GASLAND Gasmart E unit delivers 7.6 GPM of hot water using 199,000 BTU of natural gas power. It is designed for indoor installation and features a compact footprint measuring 16.7 by 11.6 by 16.7 inches. The device offers a high energy efficiency factor of 0.8, making it suitable for whole-house needs. You get continuous hot water with built-in safety protections against overheating and freezing.
Pros
- High flow rate of 7.6 GPM
- Energy efficient with a 0.8 UEF
- Compact 16.7-inch width fits small spaces
- Indoor installation capability
Cons
- Lower flow rate than 10.3 GPM competitors
- Not suitable for elevations over 2000 feet
- No smart connectivity or app control listed
Good fit if
- You need a compact indoor unit
- You want high energy efficiency
- You require 7.6 GPM flow
Skip if
- You live above 2000 feet elevation
- You need smart home integration
- You require 10+ GPM flow
Verdict: The GASLAND Gasmart E 199,000 BTU is a solid indoor choice for homes needing 7.6 GPM. It suits buyers who prioritize efficiency and compact size over maximum flow or smart features.
Specifications side by side
| Spec | Reliance 199,000 BTU Gas Tankless Water Heater | MIZUDO 10.3 GPM Indoor Natural Gas Tankless Water Heater | Westinghouse 10.3 GPM Natural Gas Tankless Heater | GASLAND Gasmart E 199k BTU Natural Gas | Camplux Outdoor 8.4 GPM Natural Gas Water Heater | Camplux CA686WNG 199k BTU Natural Gas | GASLAND Gasmart E 7.6 GPM Natural Gas Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas, Propane | Natural Gas | Natural Gas | not specified | Natural Gas | Natural Gas | Natural Gas |
| Flow Rate | not specified | 10.3 GPM | 10.3 GPM | not specified | Up to 8.4 GPM | 7.6 GPM | 7.6 GPM |
| BTU | 199,000 BTU | 199,000 BTU | 199,000 BTU/hr | not specified | 199,000 BTU | 199,000 BTU | 199,000 BTU |
| Installation Location | Indoor/Outdoor | Indoor | Indoor | not specified | Outdoor | Indoor | Indoor |
| Voltage | not specified | 120V | not specified | not specified | not specified | 120 V | not specified |
| Temperature Control | not specified | 95°F–149°F, ±1°F | WiFi & APP control | not specified | not specified | not specified | not specified |
| Certification | not specified | CSA | not specified | not specified | CSA | CSA, UL | not specified |
| Dimensions | 11 x 11 x 18 inches | 24.8" x 15.9" x 10.4" | not specified | not specified | 22.2 x 6.5 x 6.5 inches | 24.7 x 14.3 x 7.3 in | not specified |
| Use | not specified | Whole House | not specified | Whole House | Whole House | not specified | not specified |
| Venting Type | not specified | not specified | Non-Condensing | not specified | not specified | not specified | not specified |
| Features | not specified | WiFi | WiFi | not specified | not specified | not specified | not specified |
| Weight | 8.5 pounds | 55.5 pounds | 56 pounds | 37.5 pounds | 39 pounds | 37.5 pounds | not specified |
| Color | White | Grey 10.3NG | White | Black | White | White | Black |
| Model | X3-199 | WCIU-HW199A1G-NG-M0 | not specified | CE686NG | WA686M-NG | CA686WNG | CE686NGN2 |
| Size | not specified | Natural Gas, 10.3 GPM, 199,000 BTU, Indoor | not specified | Small | 6.86 GPM-NG | 7.6 GPM, NG | not specified |
Frequently asked questions
Which Reliance X3 alternative offers the highest flow rate?
The MIZUDO 10.3 GPM model provides the highest flow rate on this list. It delivers 10.3 gallons per minute at 199,000 BTU. This makes it suitable for whole-house use in larger homes. The unit measures 15.9 inches wide and 24.8 inches tall. It is designed for indoor installation only.
What is the best outdoor option compared to the Reliance X3?
The Camplux WA686M Outdoor is the best choice for outdoor setups. It delivers 8.4 GPM with 199,000 BTU output. The compact design measures 6.5 inches wide and 22.2 inches tall. It weighs 39 pounds and is built for exterior mounting. This model avoids indoor venting constraints entirely.
Are there smaller alternatives to the Reliance X3 for tight spaces?
The GASLAND Gasmart E is a compact indoor option. It measures 14.3 inches wide and 24.7 inches tall. The unit weighs 37.5 pounds and provides 199,000 BTU. It fits well in small closets. The color is black, offering a discreet look for tight indoor spaces.
Which model includes Wi-Fi connectivity for remote control?
The Westinghouse 10.3 GPM Smart Tankless Water Heater includes Wi-Fi. It allows app-based control for your heating needs. The unit outputs 199,000 BTU for high-demand homes. It is designed for indoor installation with non-condensing venting. This model suits large homes running multiple fixtures simultaneously.
Is there a budget-friendly alternative to the Reliance X3?
The GASLAND Gasmart E is positioned as the best budget option. It offers 199,000 BTU for indoor whole-house heating. The unit is compact, measuring 14.3 inches wide. It provides solid safety certification for residential use. This model is ideal for small indoor spaces needing high flow.
How does the Camplux CA686WNG compare to the Reliance X3?
The Camplux CA686WNG provides 7.6 GPM with 199,000 BTU. It is designed for indoor whole-house heating. The unit measures 14.3 inches wide and 7.3 inches tall. It weighs 37.5 pounds and is white. This model prioritizes high flow rates and straightforward maintenance over smart features.
Which alternative is best for homes with high hot water demand?
The MIZUDO 10.3 GPM model is best for high demand. It delivers 10.3 gallons per minute at 199,000 BTU. The unit is suitable for whole-house hot water needs. It features smart app control for precise temperature stability. This model fits well in closets or basements with indoor venting.