Best 40 Gallon Gas Hot Water Heater

Peter | 04-01-2026

With so many Best 40 Gallon Gas Hot Water Heater brands on the market – from big names like Corro-Protec,Ranein,Rheem,FOGATTI to smaller companies – finding the right product can be a real challenge. But we’re here to make your search easier.

We carefully researched and tested a vast range of Best 40 Gallon Gas Hot Water Heater to help you discover the top contenders that match different needs and preferences. Altogether, we spent over 100 hours evaluating numerous products first-hand.

Our #1 best Best 40 Gallon Gas Hot Water Heater is Corro-Protec Best 40 Gallon Gas Hot Water Heater, based on its stellar performance across all our tests. Below you’ll find more of our top-rated recommendations for great Best 40 Gallon Gas Hot Water Heater options currently available. Make sure to check out our buying guide too – it’s full of expert advice for choosing a Best 40 Gallon Gas Hot Water Heater tailored to exactly what you’re looking for. With our help guiding your decision, finding your perfect fit will be a breeze!

Editor's Choice
Corro-Protec Powered Anode Rod for Water Heater, 20-Year Warranty, Eliminates Rotten Egg/Sulfur
Corro-Protec Powered Anode Rod for Water Heater, 20-Year Warranty, Eliminates Rotten Egg/Sulfur
Premium Pick
Ranein Natural Gas Tankless Water Heater with Vent Pipe, Indoor Max 4.3 GPM, 100,000 BTU Instant Hot
Ranein Natural Gas Tankless Water Heater with Vent Pipe, Indoor Max 4.3 GPM, 100,000 BTU Instant Hot
Budget Pick
Rheem 72-40-2 240V / 4500W 40 Gallon Electric Water Heater
Rheem 72-40-2 240V / 4500W 40 Gallon Electric Water Heater

Top 10 Best 40 Gallon Gas Hot Water Heater

We researched and compared the top products in the Best 40 Gallon Gas Hot Water Heater category to provide you with these recommendations.

1. Corro-Protec Powered Anode Rod for Water Heater, 20-Year Warranty, Eliminates Rotten Egg/Sulfur

Corro-Protec Powered Anode Rod for Water Heater, 20-Year Warranty, Eliminates Rotten Egg/Sulfur
9.8

Corro-protec

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  • HASSLE-FREE HOT WATER - Corro-Protecs powered anode rods are revolutionizing the water heater maintenance by preventing and solving numerous water heater problems.
  • SAY GOODBYE TO ODORS - Eliminate your water heater odor problem by removing the rotten egg smell in hot water with our advanced powered anode rod.
  • PERMANENT CORROSION PROTECTION - Designed to replace your 40-89-gallon water heaters hex head anode rod, it can defend against any level of water hardness, including the increased corrosiveness of softened water.
  • 20-YEAR WARRANTY & QUALITY Manufactured in Canada since 2006, our hot water heater anode rod is backed by a 20-year warranty, fully compatible with your water heater warranty under U.S. MMWA law, and significantly extends the life of your tank.
  • STANDARD DEDICATED ANODE PORT INSTALLATION [standard for all water heater brands except Bradford White] - This 40-89-gallon model is designed for installation in a dedicated anode port located on top of your water heater. If you need to install your anode in the hot water outlet instead (no anode port or old anode stuck), select our anode for Bradford White tank and hot water outlet installation.
  • SAFE WITH ALL WATER SOURCES, TREATMENT SYSTEMS & WATER HEATER TYPES - Corro-Protec anodes are safe with any water sources [city and well water], water treatment systems [water softeners, filtration, reverse osmosis, etc.], and water heater tanks [electric, gas, solar, hybrid and geothermal].
  • MAXIMIZE ENERGY SAVINGS - Our energy-efficient design combats sediment build-up, enhancing water quality and prolonging tank life while saving you money on energy bills.
  • INSTALLATION SIMPLIFIED - Weve included comprehensive, easy-to-follow step-by-step instructions, ensuring a smooth installation process of the water heater anode rod and its accompanying long 12-foot cord power supply. 1" 1/16 and 1" 3/16 sockets will be required for removal and installation.
  • CERTIFIED LEAD-FREE - Our titanium mixed-metal oxide rod is not just lead-free but also boasts the prestigious Gold Seal by the Water Quality Association for your safety and trust.
  • MAXIMUM DURABILITY WITH TITANIUM - Forget about the constant replacement of aluminum anode rods or magnesium onesour titanium-made powered anode rod is maintenance-free and is made of materials that do not disintegrate.

2. Ranein Natural Gas Tankless Water Heater with Vent Pipe, Indoor Max 4.3 GPM, 100,000 BTU Instant Hot

  • Performance: The on-demand tankless water heater boasts a heating capacity of 100,000 BTU and a hot water flow rate of 4.3 gallons per minute (GPM). It can provide continuous hot water for 2-3 water supply points, making it sufficient to meet the hot water needs of a household's bathroom, kitchen, and bar area.
  • Upgrade Features: Four Seasons Function: Automatically adjust the water temperature output based on the seasonal water temperature changes. Kitchen Function: Default water output temperature is 100F, suitable for kitchen use. Bathtub Function: Adjustable water output quantity with a reminder when the set output quantity is reached, catering to various environmental needs.
  • No Waiting Required: Unlike traditional tank water heaters, tankless water heaters eliminate the need for a 30-minute preheating wait time, allowing you to have unlimited hot water on demand.
  • Save Money: The kit already includes the exhaust pipe, so you don't need to spend extra money on purchasing it separately. With an oxygen-free copper water tank, it reduces heat loss and lowers energy consumption. Applied with standard 1/2" NPT water fitting and gas inlet.
  • Recommendation: We strongly advise that all installations of the device adhere to local building and plumbing regulations at the installation location, and should be carried out by licensed professionals. Not recommended for areas over 2,000 feet.

3. 2025 GEN II Ranein Natural Gas Tankless Water Heater Max 3.6 GPM, 80,000 BTU Indoor On Demand

  • Endless Hot Water for Home Multi-Scenes: Boasts a max 3.6 GPM and 80,000 BTU for 23 taps (shower + kitchen sink + bar)no more hot water shortages for daily household use.
  • No Sudden Temp Changes, Stable Experience: Advanced tech maintains steady water temperature; no sudden spikes or dropsideal for showering or bathing infants comfortably.
  • Cut Down Monthly Utility Bills: Heats water on-demand, cutting standby energy waste versus traditional tank heaterslowers monthly gas/electric bills and supports eco-living.
  • Space-Saving for Small Spaces: Compact wall-mounted model fits apartments, small homes, or renovationsfrees up floor space while providing reliable on-demand hot water.
  • One-Click Specialized Modes: 4 preset modes (Dish 100F / Fruit 95F / Infant 104F / Elderly 107F)no manual adjustments needed for different daily needs.
  • Save Money on Extra Costs & Energy: Kit includes exhaust pipe (no extra purchase needed); its oxygen-free copper tank cuts heat loss to lower energy use, fitting standard 1/2" NPT water and gas ports.
  • Professional Installation Advice: Must be installed by licensed professionals per local building and plumbing codesnot recommended for areas above 2,000 feet elevation.

4. Rheem 72-40-2 240V / 4500W 40 Gallon Electric Water Heater

  • Rheemglas lined tank
  • R-Foam insulation
  • Anode Rod protects against corrosion
  • Automatic temperature control thermostat
  • Direct immersion heating element

5. FOGATTI Natural Gas Tankless Water Heater Indoor - Max 7.5 GPM 170,000 BTU, CSA Certified Compact

FOGATTI Natural Gas Tankless Water Heater Indoor - Max 7.5 GPM 170,000 BTU, CSA Certified Compact
8.5

Fogatti

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  • Powerhouse Performance: The FOGATTI tankless water heater takes up a third of the space of traditional tank heaters but delivers 5 times the performance. With a high heating power of 170,000 BTU and a flow rate of 7.5 GPM, it provides endless hot water on demand, perfect for multitasking households
  • Instant Heating: Unlike traditional tank heaters, this tankless water heater gas delivers instant and endless hot water as water flows through. Whether its for showers, sinks, or appliances, even for 3-5 outlet points, it ensures uninterrupted hot water whenever you need it
  • Precision Temperature Control: With advanced water servo technology and temperature sensors, the gas tankless water heater indoor precisely adjusts water flow and gas intake to maintain a temperature difference within 1. The four-stage combustion system ensures consistent comfort, whether its a chilly winter or a hot summer
  • Quick and Easy Installation: The compact design measuring 25 x 16.3 x 7.3 inches makes installation hassle-free. Tankless gas water heater is compatible with low water pressure from 15-150 PSI, ensuring smooth operation even in areas with weaker water pressure. Simply connect to a standard 120V AC for seamless operation
  • Trusted Quality and Support: Built with a high-efficiency copper heat exchanger and 304 stainless steel burner, this water heater offers exceptional durability and performance. Certified by CSA and equipped with multiple safety features, it meets the highest safety standards for reliable operation
  • Reliable Protection and Support: The FOGATTI natural gas tankless water heater includes 2 years of full coverage for the entire unit and 5 years of coverage for the heat exchanger. Our dedicated customer support team is ready to assist with any questions or concerns, providing peace of mind for you
  • Note: Important Usage Guidelines: Tankless water heater natural gas is equipped with active heating anti-freeze device, If enviroment temp drop below 5 or not be used for long period, drain the water inside to prevent damage. For optimal performance, recommended for use below 2000 feet altitude

6. Ranein Natural Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater

  • Performance: The on-demand tankless water heater boasts a heating capacity of 80,000 BTU and a hot water flow rate of 3.6 gallons per minute (GPM). It can provide continuous hot water for 2-3 water supply points, making it sufficient to meet the hot water needs of a household's bathroom, kitchen, and bar area.
  • No Waiting Required: Unlike traditional tank water heaters, tankless water heaters eliminate the need for a 30-minute preheating wait time, allowing you to have unlimited hot water on demand.
  • Provides 4 modes: Dish mode(100), Fruit mode(95), Elderly mode(104) and Infant mode(107). More convenient for you to use.
  • Save Money: The kit already includes the exhaust pipe, so you don't need to spend extra money on purchasing it separately. With an oxygen-free copper water tank, it reduces heat loss and lowers energy consumption. Applied with standard 1/2" NPT water fitting and gas inlet.
  • Recommendation: We strongly advise that all installations of the device adhere to local building and plumbing regulations at the installation location, and should be carried out by licensed professionals.(Not recommended for areas over 2,000 feet)

7. Frost King SP57/11C All Season Water Heater Insulation Blanket, 3” Thick x 48” x 75”, R10

Frost King SP57/11C All Season Water Heater Insulation Blanket, 3” Thick x 48” x 75”, R10
8.5

Frost King

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  • Vinyl backed fiberglass insulation blankets are designed for gas, oil or electric water heaters up to 60 gallon size
  • Improves Heater efficiency
  • 3 Thick x 48 x 75, R10
  • Package contains a roll of plastic tape

8. Water Heater Blanket Jacket Foam Insulation Non Fiberglass 40-80 Gallon Tank R12

Water Heater Blanket Jacket Foam Insulation Non Fiberglass 40-80 Gallon Tank R12
8

Trade Winds

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  • Kit Content: Reflective Foam Core Aluminum Foil insulation
  • 2 Pieces (4 feet) x (7 feet) + (2 feet) x (7 feet)
  • 30 feet Reflective Tape

9. Rheem 50 Gal. Smart High Efficiency Hybrid Heat Pump Water Heater with 10-Year Warranty

10. ThermoMate CZ422NG Natural Gas Tankless Water Heater, Up to 5 GPM 113,000 BTU, High Efficiency

ThermoMate CZ422NG Natural Gas Tankless Water Heater, Up to 5 GPM 113,000 BTU, High Efficiency
8.9

Thermomate

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  • [Max 5 GPM & 113,000 BTU] - The ThermoMate instant hot water heater can supply two showers simultaneously, each delivering 105F water at a flow rate of 2 GPM, based on an inlet water temperature of 65F. No waiting time, no cold water shocks, perfect for busy households. Adopting advanced water flow sensor, the built-in chip can adjust the heating power 20,000 times per second, ensuring that the hot water within 1 fluctuations for a comfortable shower experience.
  • [Safety & Reliable] - This gas tankless water heater integrates 8 protections: boil-dry, freeze, flame-out, overheating, over-temperature, pipe blockage, high-temperature lock, and excessive air pressure. Equipped with 4 ceramic heating cores, it auto-activates frost protection when temperatures hit 41F (5). The energy-smart system uses minimal electricity to generate gentle warmth, preventing pipe ice buildup without high energy costs.
  • [Energy Efficient & Save Money] - The heat exchanger is constructed from high-quality oxygen-free copper, providing superior thermal conductivity and corrosion resistance compared to stainless steel. It achieves a thermal efficiency of 98% (vs. 80% for stainless steel models) and boasts a uniform energy factor (UEF) of 0.81. This design reduces energy waste, lowering annual operating costs by approximately 30% versus traditional systems.
  • [Smart Diagnostic Display] - Equipped with a 3.5-inch LED touchscreen, it allows you to effortlessly adjust and monitor output water temperature90F to 140Fwhile providing real-time tracking of water flow, fan operation, and flame status. Advanced error code technology enables rapid diagnosis of water heater malfunctions. The UL-certified 120V/5-foot power cord ensures continuous power supply for real-time monitoring systems.
  • [Easy to Install & Save space] - The whole house tankless water heater features standard 3/4" NPT water inlet/outlet connectors, a 1/2" NPT gas inlet, a 3" OD vent, and a UL-approved 120V plug, ensuring compatibility with most households. With its compact dimensions of 21"H x 13"W x 7"D, the on-demand water heater requires less than one-third of the space occupied by traditional tank models, freeing up valuable room in your home.
  • [Wind Resistant] - Engineered with a DC High-speed Fan (360Pa static pressure/3000 RPM), the system ensures powerful exhaust evacuation capable of withstanding winds from a major hurricane (Category 3 and above, >111 mph/178 km/h), eliminating safety risks like backdraft and flameouts during the most extreme weather.

Peter

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