For consistent, on-demand hot water in homes or off-grid locations, the best 40 gallon LP water heater is a critical appliance. It delivers reliable heating performance for households of various sizes, ensuring comfort without relying on grid electricity. Choosing the right unit is vital, as a mismatch in capacity, energy efficiency ratings, or installation requirements can lead to insufficient hot water or unnecessary operational expenses.
Factors like BTU input, recovery rate, and venting options significantly influence performance and safety. With numerous models available, selecting the ideal 40-gallon propane water heater requires careful consideration of your specific needs and budget.
Explore our curated selection of the top 10 best 40 gallon LP water heaters to make an informed decision.
For a best 40 gallon LP water heater experience, consider tankless propane models that ensure continuous hot water, such as the Rheem RTG-84DVLP-3 with its 8.4 GPM flow rate, or the Westinghouse Smart Outdoor Propane Tankless Water Heater offering 8.1 GPM. These high-efficiency units are designed for consistent performance and endless hot water supply, a significant upgrade from traditional tank heaters.
Best 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 use | Check Price |
Best Pick 2  | Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water Best for: Efficient outdoor propane | Check Price |
Best Pick 3  | Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water Best for: Efficient indoor natural gas | Check Price |
Best Pick 4  | Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater Best for: Tank replacement | Check Price |
Best Pick 5  | Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Best for: Efficient indoor natural gas | Check Price |
How We Picked
To identify the best 40 gallon LP water heater, we prioritized real-world performance, build quality, and durability. We evaluated GPM output and BTU ratings to assess capacity for multiple simultaneous uses. Safety features and innovative technologies like smart controls were key.
Rouged-out options lacking robust warranties or clear suitability for 40-gallon replacement were excluded. Products offering flexible installation (indoor/outdoor) and high efficiency, like the Rheem RTG-84DVLP-3, scored highly, ensuring consistent, reliable hot water for years to come.
What Most Buyers Get Wrong
Tankless vs. Tanked: Understanding Your Flow Rate
When considering a 40-gallon propane water heater, the biggest decision is often tankless versus tanked. Tankless models like the Westinghouse Smart Outdoor Propane Tankless Water Heater (8.1 GPM) or the Rheem RTG-70XLP-3 (7.0 GPM) provide endless hot water, ideal for busy households with multiple simultaneous uses. However, ensure the Gallons Per Minute (GPM) rating meets your needs.
For instance, 7 GPM is typically adequate for 2-3 bathrooms, but if you have higher demand, look for models like the Rheem RTGH Series at 8.4 GPM.
Propane Sizing: BTU Matters for On-Demand Heating
For propane tankless water heaters, understanding the BTU (British Thermal Unit) output is crucial. Higher BTU ratings mean more powerful heating and thus, a higher GPM capacity. Models like the Westinghouse (180,000 BTU) and Rheem RTG-84DVLP-3 (180,000 BTU) offer ample power for high-demand situations.
Compare this to a unit like the CAMPLUX Climatech (5.28 GPM), which may have a lower BTU output and thus a more limited flow rate, potentially impacting how many fixtures can run simultaneously during peak usage.
1. Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000
Best for: Whole home & simultaneous fixtures.
8.1 GPM flow rate and 180,000 BTU heat output deliver endless hot water for up to 5 fixtures at once, perfect for busy households.
This outdoor propane tankless unit boasts precise ±1°F temperature stability, ensuring consistent comfort by automatically adjusting gas and water flow. Its 150 PSI maximum pressure rating supports reliable operation for showers, sinks, and laundry.
Pros
- 8.1 GPM flow rate for high demand
- 180,000 BTU heat output for strong performance
- ±1°F temperature stability for comfort
- Supports 3-5 fixtures simultaneously
Cons
- Requires outdoor installation, limiting placement options.
Ideal for large families needing continuous hot water. This unit ensures everyone gets a hot shower, even during peak morning routines.
2. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water
Best for: 2-3 bathroom homes & peak demand.
7.0 GPM flow rate means this outdoor tankless unit is ideal for homes with multiple hot water needs, from showers to laundry.
Powered by 160,000 BTUs of liquid propane, this high-efficiency unit provides fast, reliable hot water, catering to busy households. Its durable metal cabinet and compact design facilitate easy wall mounting for qualified installers.
Pros
- 7.0 GPM flow rate for good capacity
- 160,000 BTU heat output
- Durable metal cabinet
- Hot-start programming
Cons
- Requires specialized installation due to its outdoor-only design.
This Rheem model suits 2-3 bathroom homes facing high demand. It reliably supplies hot water for showers and appliances simultaneously.
3. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Best for: Outdoor installation & reliable performance.
7.0 GPM flow rate is perfect for supplying hot water to 2-3 bathrooms even when multiple fixtures are in use.
This indoor tankless unit uses natural gas with a 160,000 BTU output for rapid heating. It features a high-efficiency design with self-diagnostic programs, freeze protection, and a low activation flow rate for consistent performance.
Pros
- 7.0 GPM flow rate
- 160,000 BTU heat output
- Features freeze protection
- Low activation flow rate
Cons
- Operates on natural gas, not suitable for propane-only systems.
Excellent for homes with natural gas lines needing a reliable hot water supply. It supports simultaneous use in showers and laundry areas.
4. Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater
Best for: Direct 40-gallon tank replacement.
This indoor tankless water heater offers a direct replacement for existing 40-gallon tank models, providing endless hot water.
With a 6.6 GPM flow rate, this unit eliminates waiting for hot water. Its high-efficiency design helps reduce energy consumption while offering a continuous supply for household needs.
Pros
- Endless hot water supply
- Direct 40-gallon tank replacement
- High efficiency
- 6.6 GPM flow rate
Cons
- Specific BTUs or heat output not detailed, potentially impacting very high demand.
Homeowners looking to upgrade from a traditional 40-gallon tank will find this ideal. It offers the convenience of continuous hot water without the space of a tank.
5. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water
Best for: Indoor natural gas homes.
Delivers 7.0 GPM of hot water, ideal for homes with 2-3 bathrooms needing concurrent hot water for showers and laundry.
This indoor tankless unit is powered by natural gas with a 160,000 BTU output for fast heating. It features a durable, compact metal cabinet and easy wall mounting, plus an integrated digital display for convenience.
Pros
- 7.0 GPM flow rate
- 160,000 BTU heat output
- Integrated digital display
- Compact metal cabinet
Cons
- The unit is not smart home compatible.
Perfect for homes with natural gas infrastructure seeking an efficient indoor tankless solution. It’s designed for consistent hot water for multiple simultaneous uses.
6. CAMPLUX Climatech 5 Tankless Water Heater Propane Outdoor, 5.28 GPM
Best for: Outdoor propane & multiple water points.
Up to 6.4 GPM provides instant hot water on demand, capable of supplying 3-5 water points simultaneously.
This CAMPLUX outdoor propane water heater delivers 150,000 BTU for efficient heating. It features advanced protections including anti-freezing, dry combustion, and high water pressure, ensuring safe and reliable operation.
Pros
- 6.4 GPM flow rate
- Up to 5 water points simultaneously
- CSA Certified
- Multiple safety protections
Cons
- This is an electric model, not powered solely by propane.
Best for outdoor installations requiring substantial hot water for multiple simultaneous uses. This unit is CSA certified and built with safety features.
7. MIZUDO Tankless Water Heater Propane, Indoor or Outdoor Convertible Installation,
Best for: Flexible installation & smart control.
5.1 GPM flow rate supports 2 to 4 usage points, delivering on-demand hot water for various household needs.
This propane tankless water heater offers flexible indoor or outdoor installation with optional accessory kits. It includes WiFi and app control, allowing remote temperature adjustments and energy usage monitoring.
Pros
- 5.1 GPM flow rate
- Indoor/Outdoor convertible installation
- WiFi and App control
- Automatic anti-freeze protection
Cons
- Accessory kits for convertible installation are sold separately.
Homeowners seeking flexible installation and smart control will appreciate this model. It is suitable for homes needing hot water for 2-4 simultaneous points.
8. Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120
Best for: High flow rate & simultaneous use.
8.4 GPM flow rate is suitable for demanding households, providing plenty of hot water for multiple fixtures simultaneously.
This tankless unit operates with a 157,000 BTU heat output and offers adjustable temperature settings from 100 to 140°F. It features electric ignition and exclusive hot start programming for efficient operation.
Pros
- 8.4 GPM flow rate
- 157,000 BTU heat output
- Electric ignition
- Exclusive Hot Start Programming
Cons
- Warranty details are limited to specific timeframes for different components.
Ideal for larger homes or those with significant hot water demands. It ensures simultaneous use of showers and appliances without interruption.
9. Rheem RTG-84DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water
Best for: Indoor, high-demand propane supply.
8.4 GPM flow rate ensures ample hot water for 2-3 bathroom homes, even during peak usage times.
Powered by liquid propane with a 180,000 BTU output, this indoor tankless unit provides fast, reliable hot water. Its durable, compact metal cabinet supports easy wall mounting for qualified installers.
Pros
- 8.4 GPM flow rate
- 180,000 BTU heat output
- Durable, compact metal cabinet
- LeakGuard Leak Detection
Cons
- Requires liquid propane and indoor installation.
This model is perfect for homes with liquid propane that require high-capacity hot water delivery indoors. It handles multiple simultaneous demands with ease.
10. GE Appliances 30 Gallon Electric Water Heater with Adjustable Thermostat,
Best for: Compact electric for 1-3 persons.
This 30-gallon electric water heater provides a real capacity to deliver 53 gallons of hot water in the first hour of use.
With 5500 watts of power and a 240-volt rating, this unit offers quick recovery for consistent hot water. It’s designed for a household size of 1 to 3 persons, providing ample hot water for daily needs.
Pros
- True 30-gallon capacity
- 53 gallons first-hour rating
- Quick recovery
- Adjustable thermostat
Cons
- Requires a 240-volt electrical connection, not compatible with standard 120-volt outlets.
Suitable for smaller households of 1-3 people needing a reliable electric hot water source. Its compact size and quick recovery make it efficient for daily use.
BTU Output vs. GPM: Sizing Beyond the Specs
When selecting the best 40 gallon lp water heater, the most critical, yet often misunderstood, deciding factor isn’t tank size, but the interplay between BTU output and Gallons Per Minute (GPM) flow rate to match your household’s peak demand. Focusing solely on a stated GPM without considering the energy input is a recipe for disappointment, as undersized BTU ratings will choke even a high GPM unit, leading to lukewarm water during simultaneous use.
Consider the Westinghouse Smart Outdoor Propane Tankless Water Heater with its impressive 8.1 GPM and 180,000 BTU rating. This combination signifies a unit designed to handle significant simultaneous demand, like multiple showers running while a dishwasher cycles. Compare this to the CAMPLUX Climatech 5 Tankless Water Heater Propane Outdoor, rated at up to 6.4 GPM.
While 6.4 GPM sounds adequate, its lower BTU output (implied by the overall product positioning, though not explicitly stated as a comparable figure to the higher-end models in its listing) means it will struggle far more under heavy load, potentially delivering a noticeable drop in temperature when more than one faucet is active.
The Rheem RTG-84DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water, boasting 8.4 GPM and 180,000 BTUs, represents the higher end of performance where robust energy delivery fuels exceptional flow. This is the kind of unit that justifies the investment for larger homes with demanding hot water needs. Even within tankless models, the difference between, say, a 7.0 GPM unit like the Rheem RTG-70XLP-3 and these higher-flow units, is compounded by their respective BTU inputs.
A 7.0 GPM unit with 160,000 BTUs will perform differently than a 7.0 GPM unit with a higher BTU input, especially in colder climates where more energy is needed to raise the water temperature sufficiently.
Noritz EZTR40LP 40 gal Tank Replacement Indoor Tankless Water Heater, while offering the convenience of a direct tank replacement, operates on a fundamentally different principle by retaining a 40-gallon buffer. This stored capacity masks the flow rate limitations inherent in many tankless designs when their BTU output isn’t matched to the GPM. For true, on-demand performance capable of sustaining multiple concurrent hot water uses without compromise, prioritize the highest practical BTU output that aligns with your desired GPM, accepting that these units will typically be larger and more powerful than standard tank units or lower-spec tankless alternatives.
For households requiring robust, uninterrupted hot water at multiple points of use, the Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000 BTU, offers a clear advantage by providing ample energy to sustain its high flow rate effectively.
What to Consider for Your 40 Gallon LP Water Heater
Energy efficiency and input rate
To find the most efficient 40-gallon LP water heater, prioritize a high Energy Factor (EF) rating, which denotes how much hot water is produced per unit of energy consumed. Look for models with an EF of 0.60 or higher. The First Hour Rating (FHR) is crucial for determining how much hot water the unit can deliver in the first hour of use; aim for an FHR that comfortably exceeds your household’s peak demand, typically 70-80 gallons for a family of four.
BTU input is also key; a higher BTU input (around 40,000 BTU/hr for a 40-gallon tank) means faster recovery. Choose the highest EF and FHR that meets your hot water needs.
Venting type and installation requirements
Venting is a critical safety and installation consideration for your LP water heater. Direct vent models seal combustion air from your home’s interior, drawing it from outside and exhausting it through a paired pipe system, making them ideal for interior installations with minimal space and improved safety. Natural vent models require a vertical vent pipe to expel exhaust gases.
Always check manufacturer specifications for required clearances around the unit, typically a few inches on all sides and above. For most homes, a direct vent model offers superior safety and flexibility.
Select a direct vent for reliable and safe operation in any location.
Ignition type and durability
When evaluating the ignition system, choose electronic ignition for superior efficiency and reliability over older pilot light systems, which constantly consume a small amount of gas. For tank durability, inspect the anode rod; a magnesium or aluminum anode rod offers good longevity, but a powered anode rod provides the longest lifespan by actively preventing corrosion. Tank construction with a glass or ceramic lining over steel offers excellent protection against rust.
Opt for an electronic ignition and a powered anode rod for the most durable and maintenance-free long-term performance.
Certifications and standards
Ensure your chosen 40-gallon LP water heater meets stringent safety and efficiency standards. Look for ENERGY STAR certification, which guarantees superior energy efficiency, saving you money on fuel costs. UL listing is a non-negotiable safety mark, indicating the product has been tested and meets recognized safety requirements.
While PWMA standards are more common for pool heaters, ensuring the unit adheres to all relevant safety certifications like UL is paramount. Always select models with ENERGY STAR certification and UL listing for guaranteed safety and efficiency.
Which Should You Choose?
- If you need endless hot water for a larger home with multiple bathrooms, choose a high-GPM tankless propane unit with at least 180,000 BTU.
- If you’re replacing an existing 40-gallon tank and want a simple upgrade to endless hot water, choose an indoor tankless unit designed as a direct replacement.
- If you prioritize flexibility and have outdoor installation capabilities, choose an outdoor tankless propane model that can handle demands for 2-3 bathrooms.
Quick Best 40 Gallon Lp Water Heater Buying Checklist
- Check BTU Input: Ensure the heater’s BTU output (typically around 40,000) matches your household’s hot water demand.
- Verify Energy Factor (EF): Look for a higher EF rating, indicating greater energy efficiency and lower operating costs.
- Consider First Hour Rating (FHR): This spec shows how much hot water the heater can deliver in the first hour.
- Determine Venting Type: Decide between direct vent or natural vent based on your installation location and safety needs.
- Inspect Anode Rod: A durable anode rod, often aluminum or magnesium, helps prevent tank corrosion and extends lifespan.
- Confirm Certifications: Look for ENERGY STAR and UL listings to ensure safety, efficiency, and performance standards are met.
Frequently Asked Questions
What Is The Typical Btu Input For A 40-Gallon Lp Water Heater?
A standard 40-gallon LP water heater typically features a BTU input rate around 40,000 BTUs per hour. This ensures sufficient power to heat the tank content effectively and meet household hot water needs on demand.
How Does The Energy Factor (Ef) Affect My Operating Costs?
A higher Energy Factor (EF) rating indicates a more energy-efficient water heater, meaning less energy is wasted during the heating process. This translates directly to lower propane consumption and reduced utility bills over time.
Why Is The First Hour Rating (Fhr) Important For A 40-Gallon Lp Water Heater?
The First Hour Rating (FHR) is crucial as it quantifies the amount of hot water a heater can supply in one hour, starting with a full tank. This helps determine if the unit can handle peak demand periods, like multiple showers or laundry cycles.
What’S The Difference Between Direct Vent And Natural Vent For Lp Water Heaters?
Direct vent models pull combustion air from outside and vent exhaust gases directly outdoors through a sealed system, enhancing safety. Natural vent models rely on natural draft and a vertical chimney for exhaust, requiring more specific installation conditions.
How Can I Ensure My 40-Gallon Lp Water Heater Is Protected From Corrosion?
Look for a robust anode rod, typically made of magnesium or aluminum, which is designed to corrode sacrificially, protecting the tank lining. Regular inspection and replacement of this rod are key to preventing tank damage and ensuring longevity.
Final Words
Investing in the best 40 gallon LP water heater ensures reliable and efficient hot water for your home or cabin. With proper energy efficiency ratings and durable construction, these units offer significant value and consistent performance. Make the informed choice today to enjoy peace of mind and uninterrupted hot water.