6 Best Alternatives to the MIZUDO Natural Gas Tankless Water Heater (2026)
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You are looking for mizudo natural gas tankless water heater alternatives because the original unit may not fit your specific space or flow requirements. The MIZUDO 8.1 GPM model delivers 180,000 BTU with precise temperature control and a remote display. It is designed for outdoor whole-house use across multiple fixtures. However, you might need a different flow rate, a more compact footprint, or a different brand reputation. Some buyers prefer higher output for larger homes, while others need lower profiles for tight installations. The alternatives listed here share key specifications with the MIZUDO unit, ensuring they meet similar performance standards.
Each option on this list of 6 alternatives was selected because its published specs overlap with the original product. You will find models with higher GPM for greater simultaneous demand, or more compact dimensions for constrained outdoor areas. Some units offer smart app control, while others focus on raw durability and simple operation. By comparing these specs, you can identify the best match for your household’s hot water needs. This guide helps you navigate the differences in BTU output, physical size, and feature sets to make an informed decision.
Our top pick: MIZUDO 8.1 GPM Outdoor Natural Gas Tankless Heater.
Key differences from the MIZUDO unit
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
The Ranein 8.5 GPM model offers a higher flow rate of 8.5 gallons per minute compared to the MIZUDO’s 8.1 GPM. It also provides 190,000 BTU of heating input, which is 10,000 BTU more than the MIZUDO. This extra power supports simultaneous use in larger households. The unit is slightly narrower at 15.1 inches wide, making it easier to fit in tight outdoor spaces. It lacks the MIZUDO’s remote control panel, so you adjust settings directly on the unit. Choose this if you prioritize maximum flow and heating power over digital convenience.
Rinnai 7.6 GPM Outdoor Natural Gas Water Heater
The Rinnai RE199eN is significantly more compact than the MIZUDO, measuring only 10.8 inches in length versus 17.1 inches. It weighs 53.3 pounds, which is heavier than the MIZUDO. The flow rate is listed as 9.8 GPM in its specs, though the title says 7.6 GPM. It uses non-condensing venting technology. This unit is ideal for tight outdoor areas where space is limited. You give up the MIZUDO’s remote display and precise ±1°F temperature control. Pick this model if physical footprint and durability are your main concerns for outdoor installation.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
The APUS unit features smart app control, a feature the MIZUDO does not list in its data. It shares the same 190,000 BTU heating input as the Ranein but uses a much slimmer design. The APUS is only 6.54 inches wide, significantly narrower than the MIZUDO’s 17.1 inches. It weighs 42.5 pounds. This compact size makes it suitable for very constrained outdoor mounting locations. You trade the MIZUDO’s physical remote panel for digital management via an app. Select this option if you want modern connectivity and a minimal visual profile on your exterior wall.
Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater
The Rheem RTG-95XLN-3 delivers a higher flow rate of 9.5 GPM, surpassing the MIZUDO’s 8.1 GPM. It includes WiFi connectivity for remote monitoring, which the MIZUDO lacks. The unit is shorter at 20.8 inches high and narrower at 13.5 inches wide. It weighs 39.3 pounds, making it lighter than the MIZUDO. This model is built for high-demand households needing robust performance. You lose the MIZUDO’s dedicated remote display panel but gain digital integration. Choose this if you need higher flow rates and smart home compatibility for your outdoor water heating setup.
VELPAX 5.26 GPM Outdoor Natural Gas Water Heater
The VELPAX 5.26 GPM model has a lower flow rate than the MIZUDO, making it better for smaller households or single-fixture use. It features a digital display for precise temperature control, similar to the MIZUDO’s LED panel. The unit is narrower at 14.4 inches wide. It is designed for precise temperature stability in low-pressure environments. You give up the MIZUDO’s higher 8.1 GPM capacity and remote operation. Pick this model if you prioritize steady temperature performance and digital feedback over maximum hot water volume for multiple simultaneous uses.
Westinghouse 8.1 GPM Outdoor Natural Gas Heater
The Westinghouse unit matches the MIZUDO with an 8.1 GPM flow rate and similar outdoor design. It is slightly taller at 26.8 inches compared to the MIZUDO’s 26.2 inches. The width is identical at 17.1 inches. It weighs 42 pounds, which is slightly less than the MIZUDO. This model provides steady hot water for three to five fixtures. It lacks the MIZUDO’s specific remote control panel and ±1°F precision claims. Choose this if you want a comparable flow rate and robust outdoor durability without needing the advanced digital temperature management features of the original.
Quick picks
Our 7 picks
MIZUDO 8.1 GPM Outdoor Natural Gas Tankless Heater
Best for: outdoor whole-house hot water with remote control
- Fuel Type
- Natural Gas
- Flow Rate
- Up to 8.1 GPM
- BTU
- 180,000 BTU
- Installation Location
- Outdoor
- Voltage
- 120V
- Temperature Control
- 95–167°F, ±1°F
View on Amazon: MIZUDO 8.1 GPM Outdoor Natural Gas Tankless Heater Affiliate link
The MIZUDO 180,000 BTU unit delivers 8.1 GPM of hot water for whole-house use. It features ±1°F temperature precision and a low 0.53 GPM activation threshold. The compact 26.2 x 17.1 x 7.1 inch design fits outdoor spaces. It includes a large LED display and remote control. This model suits busy households needing reliable, on-demand heating.
Pros
- 8.1 GPM flow rate supports 2–3 bathrooms
- ±1°F precise temperature control up to 167°F
- 0.53 GPM low-flow activation for efficiency
- Includes indoor remote panel with LED display
Cons
- 180,000 BTU is lower than the 190,000 BTU competitors
- Not recommended for elevations above 2,000 feet
- 2-year full unit warranty is shorter than industry standards
Good fit if
- You need precise temperature stability for soaking tubs
- You have an outdoor installation space available
- You want a unit with remote temperature adjustment
Skip if
- You live at an elevation above 2,000 feet
- You require indoor installation capabilities
- You need a flow rate higher than 8.1 GPM
Verdict: MIZUDO 180k BTU Outdoor Tankless offers precise temperature control and remote operation for outdoor whole-house hot water needs.
Ranein 8.5 GPM Outdoor Natural Gas Water Heater
Best for: high-flow outdoor family use
- Fuel Type
- Natural Gas
- Flow Rate
- 8.5 GPM
- BTU
- 190,000 BTU
- Installation Location
- Outdoor
- Dimensions
- 24.3 x 15.1 x 15.1 in
- Weight
- 44 pounds
View on Amazon: Ranein 8.5 GPM Outdoor Natural Gas Water Heater Affiliate link
The Ranein RHO19K-NG delivers 190,000 BTU of heating power and an 8.5 GPM flow rate for outdoor use. Its compact 24.3 x 15.1 x 8.1 inch frame fits tight spaces. The unit includes anti-freeze protection and a bottom-mounted fan for safety. You get unlimited hot water without waiting. This model suits families needing high output at a budget price.
Pros
- 190,000 BTU/hr heating capacity
- 8.5 GPM maximum flow rate
- Anti-freeze protection included
- Compact 24.3 x 15.1 x 8.1 inch size
Cons
- Not recommended for elevations over 2,000 feet
- 44-pound weight requires sturdy mounting
- No remote control or digital display listed
Good fit if
- You need high flow for multiple outlets
- You have an outdoor installation spot
- You want strong heating power on a budget
Skip if
- You live above 2,000 feet elevation
- You need indoor installation
- You require remote operation
Verdict: Ranein 8.5 GPM Natural Gas Heater provides robust 190,000 BTU output for outdoor family use. It fits buyers who prioritize flow rate and budget over smart features.
Rinnai 7.6 GPM Outdoor Natural Gas Water Heater
Best for: compact outdoor spaces with moderate hot water needs
- Fuel Type
- Natural Gas
- Flow Rate
- 9.8 GPM
- BTU
- 199k BTU
- Installation Location
- Outdoor
- Dimensions
- 24.6 x 14.1 x 10.8 in
- Venting Type
- Non-Condensing
View on Amazon: Rinnai 7.6 GPM Outdoor Natural Gas Water Heater Affiliate link
The Rinnai RE199eN is a non-condensing natural gas unit designed for outdoor installation. It delivers 7.6 GPM of hot water, supporting up to six fixtures simultaneously. The compact footprint measures 24.6 x 14.1 x 10.8 inches and weighs 53.3 pounds. It features an LED screen for error codes and service reminders. This model suits homes needing reliable high-flow output in a small, durable package.
Pros
- Provides 7.6 GPM flow rate for multiple simultaneous fixtures
- Compact dimensions fit tight outdoor spaces
- LED screen displays error codes and service reminders
- 15-year heat exchanger warranty for long-term durability
Cons
- Lower flow rate than the 9.5 GPM Rheem alternative
- WiFi control module sold separately
- Professional installation is required
Good fit if
- You need a compact unit for limited outdoor space
- You want a durable unit with a long heat exchanger warranty
- You require hot water for up to six fixtures
Skip if
- You need a flow rate above 8 GPM
- You want built-in WiFi connectivity without extra purchases
- You are looking for a DIY-friendly installation
Verdict: Rinnai RE199eN 7.6 GPM Outdoor is a solid choice for households prioritizing durability and compact size over maximum flow rate. It fits well in tight outdoor areas where space is limited.
APUS 190,000 BTU Outdoor Natural Gas Water Heater
Best for: Smart app control and high flow
- Fuel Type
- Natural Gas
- Flow Rate
- 8.1 GPM
- BTU
- 190,000 BTU
- Installation Location
- Outdoor
- Voltage
- 120V AC
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: APUS 190,000 BTU Outdoor Natural Gas Water Heater Affiliate link
The APUS 190,000 BTU unit delivers 8.1 GPM of instant hot water for whole-house use. It features smart temperature control via the Tuya app or a wired controller, maintaining accuracy within ±1°F. The compact outdoor design connects to 120V AC power and includes oxygen-free copper heat exchangers. This model suits users seeking precise digital management and reliable performance for multiple simultaneous water points.
Pros
- High 190,000 BTU output for strong flow
- App and wired controller for remote adjustments
- Precise ±1°F temperature stability
- Ultra-low 0.79 GPM minimum flow requirement
Cons
- Requires 120V AC electrical connection
- Only 2-year full warranty coverage
- Outdoor installation only
Good fit if
- You want precise digital temperature control via an app
- You have a standard 120V AC outlet nearby
- You need a unit for outdoor installation
Skip if
- You require a condensing indoor model
- You prefer a longer warranty period
- You lack access to 120V AC power
Verdict: APUS 190k BTU Natural Gas Outdoor Heater is a solid choice for users who value smart app control and stable temperatures. It fits homes needing high flow rates with digital management.
Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater
Best for: high-flow outdoor whole house use
- Fuel Type
- Natural Gas
- Flow Rate
- 9.5 GPM
- BTU
- 199,900 BTU/hr
- Installation Location
- Outdoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater Affiliate link
The Rheem RTG-95XLN-3 delivers 9.5 GPM at a 35°F rise, powered by 199,900 BTUs of natural gas. Its non-condensing design allows outdoor installation without complex venting. You get precise digital control with ±1°F accuracy. The unit weighs 39.3 pounds and measures 20.8 by 13.5 by 9.4 inches. It suits large homes needing high flow rates for multiple simultaneous showers.
Pros
- 9.5 GPM flow rate supports 3-4 simultaneous showers
- 199,900 BTU/hr output for high demand
- ±1°F digital temperature precision
- Outdoor-ready non-condensing design
Cons
- No WiFi connectivity in this specific model
- Requires professional installation
- Heavier at 39.3 pounds than some alternatives
Good fit if
- You need high flow for multiple bathrooms
- You prefer outdoor installation without venting
- You want precise temperature control
Skip if
- You want built-in WiFi control
- You need a compact indoor unit
- You prefer DIY installation
Verdict: Rheem RTG-95XLN-3 9.5 GPM provides robust performance for large households with high hot water demands. It is ideal for outdoor setups where high flow and precision matter more than smart features.
VELPAX 5.26 GPM Outdoor Natural Gas Water Heater
Best for: precise temperature control and remote operation
- Fuel Type
- Natural Gas
- Flow Rate
- 5.26 GPM
- BTU
- 120,000 BTU/hr
- Installation Location
- Outdoor
- Capacity
- 20L
- Voltage
- 120V AC
View on Amazon: VELPAX 5.26 GPM Outdoor Natural Gas Water Heater Affiliate link
The VELPAX unit delivers 5.26 GPM at 120,000 BTU for outdoor natural gas use. It features an LED digital display and remote control for precise temperature adjustments between 95°F and 149°F. Advanced water servo technology keeps fluctuations within ±1°F. The stainless steel body and oxygen-free copper tank ensure durability. This model operates on low water pressure starting at 3.6 PSI, making it suitable for various outdoor setups.
Pros
- LED smart digital display for easy temperature viewing
- Includes remote control panel for indoor operation
- Precise temperature control with ±1°F fluctuation
- Operates on low water pressure starting at 3.6 PSI
Cons
- Lower flow rate of 5.26 GPM compared to competitors
- Lower BTU output of 120,000 BTU/h
- Heavier build with stainless steel and copper components
Good fit if
- You need precise temperature control within ±1°F
- You want a remote control for indoor operation
- You have low water pressure starting at 3.6 PSI
Skip if
- You require a flow rate above 5.26 GPM
- You need a BTU output higher than 120,000
- You prefer a lighter aluminum construction
Verdict: VELPAX 5.26 GPM Natural Gas Outdoor Heater offers precise temperature stability and remote convenience for users prioritizing control over raw output. It fits buyers who value steady performance in low-pressure environments rather than maximum flow.
Westinghouse 8.1 GPM Outdoor Natural Gas Heater
Best for: steady outdoor hot water for 3-5 fixtures
- Fuel Type
- Natural Gas
- Flow Rate
- 8.1 GPM
- BTU
- 180,000 BTU
- Installation Location
- Outdoor
- Voltage
- 120V AC
- Temperature Control
- 95–158°F, ±1°F
View on Amazon: Westinghouse 8.1 GPM Outdoor Natural Gas Heater Affiliate link
This Westinghouse unit delivers 8.1 GPM at 180,000 BTU for whole-home outdoor use. It supports 3–5 fixtures and maintains temperature within ±1°F. The compact 26.8-inch height fits standard spaces. CSA certification ensures safety. It requires 120V AC power. This model suits households needing reliable, steady hot water without large indoor footprint.
Pros
- 8.1 GPM flow rate supports multiple simultaneous fixtures
- ±1°F temperature stability reduces cold water fluctuations
- CSA certified for outdoor safety and reliability
- Compact 26.8 x 17.1 x 17.1 inch footprint
Cons
- 2-year limited warranty is shorter than the 5-year heat exchanger coverage
- Requires 120V AC electrical connection for operation
- Heavier at 42 pounds compared to lighter competitors
Good fit if
- You need steady temperature control within ±1°F
- You require outdoor installation with CSA certification
- You want to run 3–5 fixtures simultaneously
Skip if
- You need a higher flow rate than 8.1 GPM
- You prefer indoor installation only
- You want a warranty longer than 2 years for the unit
Verdict: Westinghouse 8.1 GPM Natural Gas Outdoor Heater provides precise temperature control and robust outdoor durability. It fits homes needing reliable multi-fixture performance without the bulk of larger units.
Specifications side by side
| Spec | MIZUDO 8.1 GPM Outdoor Natural Gas Tankless Heater | Ranein 8.5 GPM Outdoor Natural Gas Water Heater | Rinnai 7.6 GPM Outdoor Natural Gas Water Heater | APUS 190,000 BTU Outdoor Natural Gas Water Heater | Rheem RTG 9.5 GPM Outdoor Natural Gas Tankless Heater | VELPAX 5.26 GPM Outdoor Natural Gas Water Heater | Westinghouse 8.1 GPM Outdoor Natural Gas Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Natural Gas |
| Flow Rate | Up to 8.1 GPM | 8.5 GPM | 9.8 GPM | 8.1 GPM | 9.5 GPM | 5.26 GPM | 8.1 GPM |
| BTU | 180,000 BTU | 190,000 BTU | 199k BTU | 190,000 BTU | 199,900 BTU/hr | 120,000 BTU/hr | 180,000 BTU |
| Installation Location | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor | Outdoor |
| Capacity | not stated | not stated | not stated | not stated | not stated | 20L | not stated |
| Voltage | 120V | not stated | not stated | 120V AC | not stated | 120V AC | 120V AC |
| Temperature Control | 95–167°F, ±1°F | not stated | not stated | 95°F–149°F, ±1°F | ±1°F | 95°F - 149°F, ±1℉ | 95–158°F, ±1°F |
| Certification | CSA | not stated | not stated | not stated | CSA | not stated | CSA |
| Dimensions | 26.2 x 17.1 x 7.1 inches | 24.3 x 15.1 x 15.1 in | 24.6 x 14.1 x 10.8 in | 22.48 × 15.51 × 6.54 in | 20.8 x 13.5 x 9.4 inches | 23.2" x 14.9" x 6.3" | 26.8 x 17.1 x 17.1 inches |
| Use | Whole House | not stated | not stated | not stated | not stated | not stated | Whole House |
| Venting Type | not stated | not stated | Non-Condensing | not stated | Non-Condensing | not stated | not stated |
| Features | not stated | not stated | not stated | not stated | WiFi | Digital Display | not stated |
| Weight | not stated | 44 pounds | 53.3 pounds | 42.5 pounds | 39.3 pounds | not stated | 42 pounds |
| Size | Natural Gas, 8.1 GPM, 180,000 BTU, Indoor | 8.5 GPM Outdoor | 9.8 GPM | not stated | 9.5 GPM (No WiFi) | 20L | not stated |
| Color | White 8.1NG | Gray-NG | Silver | Gray | Gray | White | Grey 81NO |
| Model | HS180A0W-NG | RHO19K-NG | REU-VE2737WD-US-N | AP-AWH-W26NG | RTG-95XLN-3 | XGRSQ-White-LNG-20L | HS180A0G-NG |
If you also heat outdoor spaces, you can review appleya natural gas patio heater alternatives for your fuel supply.
Frequently asked questions
Which alternative offers the highest flow rate for whole-house use?
The Rheem RTG-95XLN-3 delivers 9.5 GPM, the highest flow rate in this comparison. It is designed for large households with significant hot water demands. This unit operates outdoors on natural gas and includes WiFi connectivity for remote monitoring. It provides robust performance where high flow and precision matter more than smart features.
Are there compact options for tight outdoor spaces?
Yes, the Rinnai REU-VE2737WD-US-N is a strong candidate for limited areas. It measures 14.1 inches wide and 10.8 inches deep, making it narrower than many competitors. It provides 7.6 GPM of hot water, which suits moderate needs. Its compact footprint allows installation in tight outdoor locations without sacrificing durability.
Which models include smart app control features?
The APUS AP-AWH-W26NG and the Rheem RTG-95XLN-3 both support digital management. The APUS unit offers smart app control for stable temperature adjustments. The Rheem model includes WiFi connectivity for remote operation. These features allow you to monitor and adjust settings from your phone, adding convenience to high-flow outdoor units.
What is the smallest physical footprint available?
The APUS AP-AWH-W26NG has the most compact dimensions, measuring only 6.54 inches in width and length. It stands 22.5 inches tall and weighs 42.5 pounds. This slim profile makes it ideal for spaces where depth is restricted. It still delivers 190,000 BTU of heating power for outdoor natural gas use.
Do any units feature a digital display for temperature control?
The VELPAX XGRSQ-White-LNG-20L includes a digital display for precise temperature management. It provides 5.26 GPM of hot water with steady performance. This model suits buyers who value control over raw output. The display helps you monitor settings accurately, ensuring consistent water temperature in low-pressure environments or for specific fixture needs.
How do the dimensions of these outdoor heaters compare?
Most units range from 13 to 17 inches in width. The Westinghouse HS180A0G-NG and MIZUDO HS180A0W-NG share similar widths of 17.1 inches. The APUS model is significantly narrower at 6.54 inches. Heights vary between 20.8 and 26.8 inches. You should measure your installation space carefully, as depth also varies, with the Rinnai being the shallowest at 10.8 inches.