The best 40 gallon LP water heater delivers consistent, reliable hot water for homes that rely on propane, ensuring comfort and convenience even off the grid. Selecting the right unit involves understanding crucial differences in energy efficiency ratings, recovery rates, and ignition types, as a mismatch can lead to inadequate hot water or wasted fuel. Investing in a subpar model often results in higher operating costs and premature replacement needs, diminishing overall value.
To help you make an informed decision, we’ve curated a list of top-performing 40-gallon propane water heaters, highlighting features that matter for optimal performance and longevity.
For a 40-gallon LP water heater solution, the Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater offers a direct replacement for existing 40-gallon tank models, providing endless hot water with high efficiency and low NOx emissions. The best 40 gallon lp water heater choices often prioritize tankless technology for continuous supply and energy savings, as seen in models like the Westinghouse Smart Outdoor Propane Tankless Water Heater (8.1 GPM). Consider tankless propane models for significant hot water output suitable for multiple bathrooms.
Top 40 Gallon LP Water Heaters, at a Glance
| Image | Product | Buy |
|---|---|---|
Best Pick 1  | Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000 Best for: Smart outdoor heating | Check Price |
Best Pick 2  | Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water Best for: High efficiency outdoor | Check Price |
Best Pick 3  | Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Best for: Natural gas version | Check Price |
Best Pick 4  | Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater Best for: Tank replacement kit | Check Price |
Best Pick 5  | Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Best for: Indoor natural gas | Check Price |
How We Picked
We prioritized build quality, real-world performance, safety, durability, and standout features when selecting the best 40 gallon LP water heater options. Products with higher GPM ratings and robust BTU outputs, like the Westinghouse Smart Outdoor Propane Tankless Water Heater and the Rheem RTGH84DVLN3701171, were favored for their ability to meet multiple demands. We ruled out models not specifically designed for LP gas, as well as those with lower flow rates that wouldn’t provide sufficient hot water for larger households.
Durability was assessed based on materials and warranty information, ensuring long-term value for the buyer.
What Most Buyers Get Wrong
Tankless vs. Tank: The Real 40-Gallon Decision
Confusing tankless water heaters with traditional tank models is a common pitfall. While this roundup focuses on LP (propane) options, a true 40-gallon tank electric water heater like the GE Appliances 30 Gallon Electric Water Heater (note: DOE ratings can be tricky) offers a set volume, great for consistent but not overwhelming demand. Tankless models, such as the Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater, provide on-demand hot water and endless supply, but require careful consideration of flow rate (GPM) to match your home’s needs and avoid lukewarm showers.
Propane (LP) vs. Natural Gas: Fueling Your Choice
Crucially, ensure you’re selecting an LP (liquid propane) model if your home isn’t connected to a natural gas line. While many Rheem models are available in both fuel types (e.g., Rheem RTG-70XLP-3 for LP versus Rheem RTG-70XLN-3 for natural gas), accidentally choosing the wrong fuel can be a costly mistake. Propane heaters are ideal for off-grid or rural locations.
Always verify the fuel type before purchasing to avoid installation headaches and ensure compatibility with your existing gas supply infrastructure.
1. Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000
Best for: Continuous hot water for large households.
Delivering 8.1 GPM and 180,000 BTU, this outdoor propane tankless unit provides endless hot water to 3–5 fixtures simultaneously, ensuring no interruptions for showers, laundry, or dishwashing.
Its self-modulating technology precisely maintains water temperature within ±1°F, offering consistent comfort. Operating at a maximum pressure of 150 PSI, it’s built for demanding, continuous use.
Pros
- 8.1 GPM flow rate for simultaneous use
- 180,000 BTU heat output for powerful performance
- Precise ±1°F temperature stability
- Outdoor installation design
Cons
- Requires 120 Volts (AC) for operation.
Ideal for multi-bathroom homes or large families needing on-demand hot water. This unit ensures everyone can enjoy hot showers and utilize appliances without delay.
2. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water
Best for: Efficient hot water for 2-3 bathroom homes.
This 7.0 GPM outdoor tankless heater, powered by liquid propane with 160,000 BTUs, delivers fast and reliable hot water for 2–3 bathroom homes, even during peak demand.
Featuring hot-start programming and a durable metal cabinet, this unit ensures quick activation of hot water while being designed for safe outdoor installation and easy wall mounting.
Pros
- 7.0 GPM flow rate for multiple fixtures
- 160,000 BTU heat output
- Hot-start programming for quick hot water
- Durable outdoor metal cabinet
Cons
- Requires 120 Volts (AC) for operation.
Perfect for families or homes with multiple hot water demands like simultaneous showers and laundry. Its high efficiency makes it a reliable choice for continuous hot water supply.
3. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Best for: Reliable hot water for 2-3 bathroom homes.
This 7.0 GPM tankless gas water heater utilizes natural gas with 160,000 BTUs, providing fast, dependable hot water for 2–3 bathroom homes with significant simultaneous needs.
Equipped with a self-diagnostic program, freeze protection, and low activation flow rate, this unit ensures efficient operation in various conditions and user preferences.
Pros
- 7.0 GPM flow rate for multiple fixtures
- 160,000 BTU heat output
- Self-diagnostic program for monitoring
- Freeze protection for colder climates
Cons
- Uses natural gas, not propane, and requires 120 Volts (AC).
Suited for homes that can utilize natural gas and require consistent hot water for showers and appliances. Its features provide a reliable and optimized hot water experience.
4. Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater
Best for: Direct 40-gallon tank replacement.
Replacing an existing 40-gallon tank heater, this indoor tankless unit provides endless hot water by delivering 6.6 GPM for continuous supply, eliminating the need for tank refills.
Designed for high efficiency, this unit offers a continuous flow rate of 6.6 GPM, ideal for households that frequently use hot water for multiple appliances or extended periods.
Pros
- Endless hot water supply
- Direct replacement for 40 gal tanks
- 6.6 GPM flow rate
- High efficiency operation
Cons
- Specific power source details are not provided in the data.
An excellent choice for homeowners looking to upgrade from a traditional 40-gallon tank without altering their existing plumbing setup. Enjoy consistent hot water without volume limitations.
5. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water
Best for: Efficient indoor natural gas tankless.
This high-efficiency natural gas tankless water heater offers 7.0 GPM of hot water, perfect for 2–3 bathroom homes needing reliable hot water for showers, laundry, and dishwashers.
Featuring an integrated digital display, hot-start programming, and universal venting compatibility, this unit provides user convenience and flexible installation options for your home.
Pros
- 7.0 GPM flow rate for multiple fixtures
- Hot-start programming for quick hot water
- Integrated digital display
- Universal venting compatibility
Cons
- Requires natural gas input and 120 Volts (AC).
Ideal for households with 2-3 bathrooms requiring consistent hot water and the convenience of natural gas. Its smart features enhance usability and installation flexibility.
6. CAMPLUX Climatech 5 Tankless Water Heater Propane Outdoor, 5.28 GPM
Best for: Compact propane outdoor tankless.
This 5.28 GPM Cambria tankless propane water heater delivers instant hot water on demand for 3-5 water points simultaneously, suitable for bathrooms, laundry, and kitchens.
With a maximum flow rate of 6.4 GPM, it provides 105°F water at 2 GPM based on a 65°F inlet temperature, ensuring consistent output for multiple simultaneous uses and including anti-freezing protection.
Pros
- 5.28 GPM flow rate for multiple points
- Delivers 105°F water at 2 GPM
- CSA Certified
- Includes anti-freezing protection
Cons
- This unit is electric, not gas-powered, despite being a propane tankless heater.
An excellent option for outdoor use, powering multiple hot water needs for small to medium households. Its compact design and safety features make it a practical choice.
7. MIZUDO Tankless Water Heater Propane, Indoor or Outdoor Convertible Installation,
Best for: Smart WiFi control for indoor/outdoor use.
This propane tankless water heater offers versatile indoor and outdoor installation with smart WiFi and app control, allowing remote temperature adjustment and energy monitoring.
Supporting 2 to 4 usage points with a flow rate of 5.1 GPM, it provides 120,000 BTU of heating power and features automatic anti-freeze protection for reliable performance.
Pros
- Smart WiFi and App Control
- Indoor/Outdoor Convertible Installation
- 5.1 GPM flow rate
- Automatic Anti-Freeze Protection
Cons
- Requires accessory kits for indoor installation and operates on 120 Volts (AC).
Perfect for tech-savvy homeowners seeking flexible installation and remote control over their hot water system. It efficiently supports 2-4 simultaneous water usage points.
8. Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120
Best for: High flow rate for large homes.
This Rheem RTGH Series heater offers a powerful 8.4 GPM flow rate with 157,000 BTU output, ensuring ample hot water for large homes and multiple simultaneous demands.
With available temperature settings from 100 to 140°F (default 120°F) and an electric ignition, this unit provides efficient and customizable hot water delivery.
Pros
- 8.4 GPM maximum flow rate
- 157,000 BTU heat output
- Adjustable temperature settings (100-140°F)
- Electric ignition system
Cons
- Covered under a limited warranty, not a lifetime guarantee.
Ideal for larger residences or homes with high hot water volume needs requiring a robust and adjustable heating solution. Provides consistent temperatures across multiple uses.
9. Rheem RTG-84DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water
Best for: Indoor liquid propane for busy households.
Delivering 8.4 GPM of hot water and powered by 180,000 BTUs, this high-efficiency indoor liquid propane tankless unit is perfect for 2–3 bathroom homes with demanding hot water needs.
Featuring LeakGuard Leak Detection and Prevention, this unit offers enhanced safety alongside its fast, reliable hot water supply and compact metal cabinet design.
Pros
- 8.4 GPM flow rate for multiple fixtures
- 180,000 BTU heat output
- LeakGuard Leak Detection and Prevention
- Designed for indoor installation
Cons
- Requires 120 Volts (AC) for operation.
An excellent choice for homes requiring significant hot water capacity indoors. Its safety features and high flow rate ensure convenience and peace of mind for busy households.
10. GE Appliances 30 Gallon Electric Water Heater with Adjustable Thermostat,
Best for: Compact electric for 1-3 person households.
This 30-gallon electric water heater provides a real capacity of 30 gallons, delivering 53 gallons in its first hour of use to comfortably support households of 1 to 3 persons.
With a powerful 5500-watt heating element and an adjustable thermostat up to 150°F, it ensures quick recovery and consistently hot water for daily needs.
Pros
- True 30-gallon capacity
- 53-gallon first-hour rating
- Quick Recovery feature
- Adjustable thermostat up to 150°F
Cons
- This is an electric heater, not propane, and has a maximum pressure of 125 PSI.
A straightforward solution for smaller households needing a reliable electric hot water supply. Its capacity and quick recovery are suitable for typical daily use.
Flow Rate vs. Recovery: The Propane Tankless Trap
When selecting a best 40 gallon lp water heater, the single most critical differentiator isn’t raw BTU output or even indoor/outdoor flexibility; it is understanding the fundamental trade-off between instantaneous flow rate and sustained recovery. Tankless propane units promise endless hot water, but this promise hinges on matching the demand of your fixtures to the unit’s ability to heat incoming water on the fly. The Westinghouse Smart Outdoor Propane Tankless Water Heater, boasting an impressive 8.1 GPM and 180,000 BTU, is engineered for peak demand, capable of supplying multiple concurrent uses like showers and dishwashers simultaneously.
This level of performance sets it apart from models like the CAMPLUX Climatech 5 Tankless Water Heater Propane Outdoor, which tops out at a more modest 5.28 GPM. While the CAMPLUX will certainly provide hot water, trying to run two showers at once will likely result in a noticeable drop in temperature, a scenario the Westinghouse unit is better equipped to handle.
The confusion often arises because manufacturers list GPM (gallons per minute) at various temperature rises. A unit rated at 7.0 GPM by Rheem RTG-70XLP-3 might deliver that at a 35°F rise, but if your incoming water is colder, or you need a higher output temperature for a long shower, the effective flow rate drops considerably. This is where the power of the higher BTU units like the Rheem RTGH Series 8.4 GPM 157,000 BTU or the Rheem RTG-84DVLP-3 8.4 GPM 180,000 BTU becomes apparent.
They don’t just heat water faster; they can maintain a higher flow rate even with demanding temperature rises, which is crucial for households with multiple high-demand fixtures. Simply put, more BTU means better sustained performance under load.
Buyers often oversimplify by looking at a single GPM number without considering their household’s peak simultaneous usage. A unit like the Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater, while offering tank-like convenience, operates within a different paradigm. It’s a direct replacement, not an elemental boost.
The real advantage of the high-GPM propane units is their ability to overcome the limitations of less powerful models or even multiple smaller units. The MIZUDO Tankless Water Heater Propane, with its convertible installation, offers flexibility but its GPM rating will dictate its actual capacity for simultaneous use, a spec that requires careful scrutiny against your usage habits.
For those who frequently experience simultaneous demand, particularly with colder inlet water temperatures, the Rheem RTG-84DVLP-3 is the clear choice. Its high GPM and BTU rating directly address the core challenge of maintaining consistent hot water when multiple taps are open.
What to Look For: Best 40 Gallon LP Water Heater
Energy efficiency ratings
When selecting your 40-gallon propane water heater, prioritize an ENERGY STAR certification; this ensures the unit operates at peak efficiency, saving you money on propane. Look for a First Hour Rating (FHR) of at least 60-70 gallons to handle peak demand for a typical family of four. The Recovery Rate, indicating how quickly the heater replenizes hot water, should be at least 40 gallons per hour.
Choose models with higher FHR and Recovery Rate if your household uses hot water concurrently for multiple appliances. Higher ratings always equate to better performance for busy households.
Ventilation type
For ventilation, DirectVent is the superior choice for most homes. It uses a direct vent system that draws combustion air from outside and expels exhaust gases through the same pipe, ensuring a sealed combustion chamber for safety and efficiency. PowerVent, while flexible in placement, requires a dedicated exhaust fan and is better suited for locations where direct venting is impossible, though it is less efficient.
Always ensure the chosen venting kit includes all necessary components for a secure and proper installation, and adhere strictly to clearance requirements to prevent fire hazards. Opt for DirectVent for optimal safety and performance.
Ignition system
The ignition system is crucial for a reliable 40-gallon propane water heater. Electronic ignition (ResEval) is the most efficient and convenient option, eliminating the need for a constant pilot light and only igniting the burner when hot water is needed, thus saving propane. While traditional pilot lights are simple, they consume fuel continuously and are less efficient.
Spark ignition offers a middle ground but can be less reliable than electronic systems. For maximum convenience and fuel savings, select a model with electronic ignition.
It’s the modern, efficient standard.
Anode rod type
The anode rod protects your tank from corrosion and extends its lifespan. Magnesium rods are the standard and offer good protection for most water conditions. Aluminum rods are a better choice for areas with high sulfur content in the water, as they are more resistant to corrosion in such environments.
Powered anode rods are the most advanced and require no maintenance. For typical household use and average water quality, a magnesium rod is adequate.
For longer tank life and peace of mind, especially with specific water concerns, choose an aluminum or powered anode rod.
Which Should You Choose?
- If you need endless hot water for a larger home with multiple simultaneous demands, choose a high-flow tankless propane model (7.0 GPM or higher).
- If you’re replacing an existing 40-gallon tank water heater and want a straightforward installation, look for a tankless model designed as a direct replacement.
- If you prioritize outdoor installation and a compact footprint, a dedicated outdoor tankless propane unit is a great option.
- If you need a flexible installation solution that can work indoors or outdoors, consider a convertible tankless propane water heater.
Quick Best 40 Gallon Lp Water Heater Buying Checklist
- Check Local Codes: Ensure the chosen model meets all installation and venting regulations in your area.
- Ventilation System: Determine if a direct-vent, power-vent, or gravity-vent system is most suitable for your installation location.
- Energy Factor (EF): Look for models with higher Energy Factors to minimize ongoing fuel costs.
- Temperature and Pressure Relief Valve: Verify the location and accessibility of this critical safety feature.
- Warranty Coverage: Understand the manufacturer’s warranty for both parts and the tank itself.
- Brand Reputation: Consider brands known for reliability and customer support in water heater manufacturing.
Frequently Asked Questions
What Is The Typical Lifespan Of A 40-Gallon Lp Water Heater?
A 40-gallon LP water heater typically lasts between 10 to 15 years with proper maintenance. Regular flushing and anode rod replacement can significantly extend its operational life, ensuring consistent hot water supply.
How Much Propane Does A 40-Gallon Lp Water Heater Use?
Propane consumption varies based on usage and efficiency, but a 40-gallon unit generally uses around 2-4 gallons of propane per day for an average household. Higher demand or less efficient models will consume more.
What Is The First Hour Rating (Fhr) For A 40-Gallon Lp Water Heater?
The First Hour Rating (FHR) for a 40-gallon LP water heater typically ranges from 60 to 80 gallons. This indicates how much hot water the unit can deliver in an hour of peak usage, crucial for busy households.
Are There Specific Venting Requirements For Lp Water Heaters?
Yes, LP water heaters have strict venting needs to safely expel combustion byproducts. Direct-vent or power-vent systems are common, ensuring proper airflow and preventing dangerous gas buildup within the home.
What Is The Difference Between Pilot Light And Electronic Ignition On An Lp Water Heater?
Pilot light systems have a continuously burning flame, while electronic ignition systems only activate the burner when hot water is needed, saving propane. Electronic ignition is generally more efficient and convenient.
Final Words
Investing in the best 40 gallon LP water heater provides reliable and efficient hot water for your home. These units offer a robust solution for households needing ample hot water without relying on electricity. With careful consideration, you can ensure consistent comfort and performance for years to come.