The best 40 gallon propane water heater provides reliable, on-demand hot water for households with moderate to high usage needs, ensuring comfort and convenience. When selecting one, consider factors like energy efficiency ratings, venting requirements, and tank insulation, as a mismatch can lead to wasted energy and inadequate hot water supply. Different models offer varying recovery rates and physical dimensions, impacting installation ease and operational cost.
Choosing the right unit is crucial for long-term satisfaction and minimizing performance issues. Explore our curated list to find the ideal 40-gallon propane water heater that balances performance, durability, and suitability for your specific requirements and lifestyle.
For efficient and reliable hot water, the best 40 gallon propane water heater options prioritize on-demand heating and high flow rates. Models like the Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water Heater or the Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM, offer powerful performance. Key features to consider include BTU output, gallons per minute (GPM) capacity for multiple simultaneous uses, and installation flexibility (indoor/outdoor).
These tankless units provide endless hot water, unlike traditional tank models.
Best 40 Gallon Propane Water Heater at a Glance
| Image | Product | Buy |
|---|---|---|
Best Pick 1  | NEW Rinnai RX180iN Condensing Smart Sense Natural Gas or Propane Best for: Smart homes | Check Price |
Best Pick 2  | Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water Best for: Outdoor use | Check Price |
Best Pick 3  | Rheem RTG-70DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water Best for: Indoor use | Check Price |
Best Pick 4  | Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000 Best for: High flow | Check Price |
Best Pick 5  | APUS Tankless Water Heater Propane, 140,000 BTU Indoor Installation Up Best for: Compact spaces | Check Price |
How We Picked
We prioritized build quality, real-world performance, safety, durability, and standout features when evaluating propane water heaters for the best 40 gallon propane water heater comparison in Units like the Rheem RTG-70XLP-3 and Westinghouse Smart Outdoor Propane Tankless Water Heater impressed with their high GPM flow rates, essential for multiple simultaneous uses. We ruled out models with questionable durability or lacking robust safety certifications.
Condensing technology, as seen in the Rinnai RX180iN, offered advanced efficiency, while others like the APUS and MIZUDO focused on powerful BTUs for rapid heating and extensive fixture support.
What Most Buyers Get Wrong
Tankless vs. Tank: Which Propane Heater Is Right?
When choosing a 40-gallon propane water heater, the biggest decision is tankless versus traditional tank. Tankless models, like the Rheem RTG-70XLP-3 or the Westinghouse Smart Outdoor unit, offer endless hot water and energy savings but require a higher initial investment and potentially more complex installation. Traditional tank heaters provide a set amount of hot water readily available, often with simpler setup, but can run out during high demand.
Consider your household’s typical hot water usage patterns to make the best choice.
BTUs: The Powering Force of Propane
The BTU (British Thermal Unit) rating signifies the heating power of your propane water heater. For instance, the MIZUDO Tankless Water Heater boasts a substantial 199,000 BTU. Higher BTU units heat water faster and can support more simultaneous hot water demands, crucial for larger homes or those with multiple bathrooms, like those potentially served by the Ranein or APUS models.
Ensure the BTU rating aligns with your home’s needs and the manufacturer’s recommendations to avoid underperformance or inefficiency.
1. NEW Rinnai RX180iN Condensing Smart Sense Natural Gas or Propane
Best for: Indoor/Outdoor Propane or Natural Gas Smart Heater.
This Rinnai RX180iN model’s dual-fuel capability allows installation indoors or outdoors with powered propane or natural gas, providing flexibility for diverse home setups.
With a flow rate of up to 10 gallons per minute, this compact unit handles up to 6 fixtures simultaneously. Its Smart Sense gas control system ensures efficient operation, and the high efficiency of 0.98 UEF means less energy waste.
Pros
- Handles 6 fixtures concurrently (10 GPM flow rate)
- Dual-fuel allows propane or natural gas use
- Indoor or outdoor installation flexibility
- High 0.98 UEF efficiency rating
Cons
- Requires a separate RX-OVC vent cap for outdoor installation.
Homeowners needing flexible fuel options and simultaneous fixture use will find this Rinnai unit ideal. Its capacity supports busy households requiring reliable hot water.
2. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water
Best for: Outdoor Liquid Propane with Hot-Start Programming.
The Rheem RTG-70XLP-3 features outdoor installation and hot-start programming to minimize cold water bursts, delivering immediate hot water upon demand.
This high-efficiency unit provides up to 7.0 GPM at 160,000 BTUs, suitable for 2–3 bathrooms with multiple simultaneous demands like showers and laundry. Its durable metal cabinet is designed for external mounting.
Pros
- Provides 7.0 GPM flow rate
- 160,000 BTU heat output
- Hot-start programming for quicker hot water
- Durable metal cabinet for outdoor use
Cons
- Requires 1/2 inch gas line compatibility, which might necessitate existing line upgrades.
This Rheem tankless water heater is designed for homeowners needing reliable outdoor propane supply for 2-3 bathrooms. Its hot-start feature enhances comfort during peak usage times.
3. Rheem RTG-70DVLP-3 High Efficiency Non-Condensing Indoor Tankless Liquid Propane Water
Best for: Indoor Liquid Propane with Hot-Start Programming.
Designed for indoor installation, the Rheem RTG-70DVLP-3 offers hot-start programming to ensure hot water is ready when you need it.
This high-efficiency, 0.82 UEF rated unit delivers 7.0 GPM with a 160,000 BTU output, making it ideal for homes with 2–3 bathrooms. Its compact metal cabinet facilitates straightforward wall mounting indoors.
Pros
- Suitable for 2-3 bathrooms (7.0 GPM flow)
- 160,000 BTU heat output
- Hot-start programming reduces wait time
- Indoor installation convenience
Cons
- Has a 0.82 UEF efficiency rating, lower than some condensing models.
Homeowners with 2-3 bathrooms prioritizing indoor installation will benefit from this Rheem unit. Its consistent performance ensures hot water availability for showers and laundry.
4. Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000
Best for: Outdoor Propane with Precise Temperature Control.
The Westinghouse Smart Outdoor Propane Tankless Water Heater offers precise ±1°F temperature stability, ensuring consistent hot water delivery for various needs.
With a flow rate of 8.1 GPM and 180,000 BTU output, this unit comfortably supports 3–5 fixtures simultaneously. Its self-modulating technology adjusts gas and water flow for optimal performance.
Pros
- Maintains ±1°F temperature accuracy
- Supplies 8.1 GPM flow rate
- Handles 3-5 fixtures concurrently
- 180,000 BTU heating power
Cons
- Designed exclusively for outdoor installation, limiting indoor placement options.
This Westinghouse tankless water heater is perfect for outdoor installation supporting households needing 3-5 fixtures simultaneously. Its precise temperature control is ideal for comfort-sensitive users.
5. APUS Tankless Water Heater Propane, 140,000 BTU Indoor Installation Up
Best for: Indoor Propane with Instant Hot Water Technology.
The APUS Tankless Water Heater utilizes a 140,000 BTU burner and Zero Cold Water Technology to provide hot water in just 1 second.
This upgraded smart propane unit features an oxygen-free copper heat exchanger for durability and boasts a 6.8 GPM flow rate. Its intelligent heating system ensures instant comfort without waiting for water to warm up.
Pros
- Provides hot water in 1 second
- Zero-Cold-Water Technology eliminates wait
- Durable oxygen-free copper heat exchanger
- Supports WiFi remote control
Cons
- Rated at 140,000 BTU, it may be less powerful than some higher-output models for very large demand.
Homeowners seeking the fastest possible hot water from an indoor propane unit will appreciate this APUS model. Its instant availability is ideal for busy mornings and continuous hot water needs.
6. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Best for: Outdoor Natural Gas with Freeze Protection.
The Rheem RTG-70XLN-3 is a high-efficiency natural gas water heater built for outdoor installation, featuring freeze protection for reliable operation in colder climates.
Delivering up to 7.0 GPM with 160,000 BTUs, this unit is well-suited for 2–3 bathroom homes. It includes a self-diagnostic program and a digital display for easy monitoring.
Pros
- Suitable for 2-3 bathrooms (7.0 GPM)
- 160,000 BTU heat output
- Freeze protection for outdoor use
- Self-diagnostic program for troubleshooting
Cons
- This model is for natural gas only and cannot be converted to propane.
This Rheem unit is the choice for homeowners with natural gas supply needing an outdoor heater for 2-3 bathrooms. Its freeze protection ensures year-round reliability.
7. Ranein Propane Gas Tankless Water Heater, Indoor Max 4.3 GPM,
Best for: Indoor Propane with 4 Intelligent Preset Modes.
This Ranein Propane Gas Tankless Water Heater operates with 4 intelligent preset modes, including 4-season auto-matching and specific settings for kitchen and bathtub.
Offering 100,000 BTU power and a 4.3 GPM flow rate, it supports 3-4 water points simultaneously. Precision temperature control links gas, water, and temperature for consistent output.
Pros
- Supports 3-4 simultaneous water points
- Four distinct preset modes for convenience
- 100,000 BTU heating capacity
- Precision temperature linkage system
Cons
- Maximum flow rate of 4.3 GPM may not be sufficient for very high-demand simultaneous use of multiple showers.
This indoor propane unit is ideal for smaller households or apartments that benefit from preset temperature modes. Its 4.3 GPM flow rate covers typical daily hot water needs.
8. MIZUDO Tankless Water Heater Propane, 199,000 BTU, Indoor Installation, Max
Best for: Indoor Propane with Smart WiFi & 10.3 GPM.
The MIZUDO Tankless Water Heater delivers a powerful 199,000 BTU output and 10.3 GPM flow rate, supported by smart WiFi connectivity for remote management.
Designed for indoor installation, this propane unit supports 5–7 fixtures simultaneously, making it suitable for large households. It features an advanced sealed combustion system and automatic anti-freeze protection.
Pros
- Supports 5-7 fixtures concurrently (10.3 GPM)
- Powerful 199,000 BTU output
- Smart WiFi and app control
- Automatic anti-freeze protection
Cons
- High BTU output may exceed requirements for smaller homes, potentially impacting efficiency if not sized correctly.
Large households needing to support 5-7 fixtures simultaneously will find this MIZUDO propane water heater ideal. Its smart connectivity and high flow rate offer convenience and ample hot water.
9. Outdoor Tankless Water Heater, 130,000 BTU/5.3 GPM Propane Instant Hot
Best for: Outdoor Propane with Anti-Freezing Protection.
This Outdoor Tankless Water Heater, rated at 130,000 BTU and 5.3 GPM, is designed for outdoor use and includes anti-freezing protection for reliable operation in various climates.
It supplies enough hot water for 130,000 BTU to meet the needs of 3–5 taps simultaneously, such as for showers and kitchen sinks. Its wind-resistant construction enhances outdoor durability.
Pros
- Supports 3-5 taps concurrently (5.3 GPM)
- 130,000 BTU heating power
- Anti-freezing protection included
- Wind-resistant construction for outdoor resilience
Cons
- Flow rate of 5.3 GPM may be insufficient for simultaneous use of more than two high-demand fixtures like showers.
Homeowners requiring an outdoor propane water heater for moderate use, such as supplying 3-5 taps, will benefit from this model. Its weather-resistant features ensure dependable performance.
10. APUS Tankless Water Heater Propane Gas, Up to 4.42 GPM,
Best for: Indoor Propane with Low-Flow Start Technology.
The APUS Tankless Water Heater Propane Gas utilizes innovative 0.66 GPM low-flow start technology, ensuring efficient operation even with minimal water usage.
This high-performance unit delivers 95,000 BTU heating capacity with a 4.42 GPM flow rate, capable of meeting simultaneous hot water demands for 2 showers plus 1 sink. High-precision sensors maintain stable temperatures.
Pros
- Starts with a 0.66 GPM flow rate
- Supports 2 showers + 1 sink simultaneously
- 95,000 BTU heating capacity
- High-precision sensors for stable temps
Cons
- The 4.42 GPM flow rate may not be adequate for households with more than 2 showers running concurrently.
This APUS propane water heater is ideal for smaller households or apartments needing efficient indoor heating. Its low-flow start technology and stable temperature control are notable benefits.
Outdoor vs. Indoor Installation Limits Propane Heater Choices
The primary differentiator among these propane water heaters isn’t peak GPM or BTU output, but whether the unit is designed for indoor or outdoor installation. This single factor dictates plumbing, venting complexity, and ultimately, which model can even be considered for your specific home configuration.
Units like the Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water and the Westinghouse Smart Outdoor Propane Tankless Water Heater, 8.1 GPM 180,000 are built with weather-resistant enclosures and specific venting requirements suitable only for external mounting. Conversely, the APUS Tankless Water Heater Propane, 140,000 BTU Indoor Installation Up and the MIZUDO Tankless Water Heater Propane, 199,000 BTU, Indoor Installation, Max are engineered for interior placement where ambient temperature is more stable, and their venting is designed for indoor exhaust systems. Attempting to install an outdoor-only unit inside, or vice-versa, introduces significant risks and code violations.
Even units with similar GPM ratings, like the Rheem RTG-70XLP-3 (7.0 GPM) versus the Westinghouse (8.1 GPM), become functionally identical if one cannot be installed at your property. The NEW Rinnai RX180iN Condensing Smart Sense Natural Gas or Propane further complicates this by offering both indoor and outdoor versatility through its Versa Vent system and dual-fuel capability, but this adaptability comes with its own set of considerations beyond mere installation location.
For those prioritizing a simple setup with existing indoor venting and no desire for complex exterior modifications, focusing solely on indoor-rated models such as the APUS Tankless Water Heater Propane, 140,000 BTU Indoor Installation Up is the most sensible approach to selecting a best 40 gallon propane water heater. Anything else introduces unnecessary complexity and expense to the purchase. To maximize efficiency in smaller spaces, the Ranein Propane Gas Tankless Water Heater, Indoor Max 4.3 GPM, offers a compact option if extensive hot water flow is not the primary concern.
What to Look For in a 40 Gallon Propane Water Heater
Energy efficiency uniform energy factor uef
When choosing a 40-gallon propane water heater, prioritize a Uniform Energy Factor (UEF) score. Higher UEF ratings indicate greater efficiency, meaning less propane is consumed for the same amount of hot water, directly lowering your operating costs. Look for UEF ratings above 0.60 for standard models and consider models with advanced efficiency features for even greater savings.
A heater with a UEF of 0.70 or higher offers superior long-term value through reduced energy bills. Select a higher UEF model for consistent savings.
Ventilation type: directvent vs atmospheric vent
The ventilation type significantly impacts installation flexibility and safety. Direct vent systems draw combustion air from outside and exhaust through a sealed pipe, making them ideal for installation in closets, interior rooms, or areas where outdoor air isn’t readily available. Atmospheric vent systems require a vertical chimney to vent exhaust gases, necessitating placement near an existing flue.
For most homes wanting flexibility in placement, a direct vent model is the superior choice for safe and convenient installation.
First hour rating fhr recovery rate
The First Hour Rating (FHR) and recovery rate determine your household’s ability to meet peak hot water demand. FHR indicates how much hot water a heater can supply in the first hour of use, crucial for mornings with multiple showers or laundry cycles. Recovery rate refers to how quickly the heater reheats water.
For a family of four or more, aim for an FHR of at least 75 gallons. Prioritize an FHR over 75 gallons to ensure an ample hot water supply without interruption.
Physical dimensions installation space
Carefully consider the physical dimensions and installation space. A standard 40-gallon propane water heater typically stands around 58 inches tall with a diameter of 20-22 inches. Ensure you have adequate vertical and horizontal clearance for proper ventilation, maintenance access, and connection to plumbing and gas lines.
Garages and basements are common, but always verify your chosen location meets the manufacturer’s specific clearance requirements. Measure your space precisely and select a unit that fits comfortably with the necessary clearances.
Which Should You Choose?
- If you need to install your water heater outside and want excellent flexibility with gas types, look for models with “Versa Vent” technology that can accommodate both propane and natural gas.
- If your primary concern is providing endless hot water for a medium-sized home with 2-3 bathrooms and multiple simultaneous needs, choose a high-efficiency outdoor tankless model with around 7.0 GPM.
- If you have limited space or prefer an indoor installation and need consistent on-demand hot water for a household of 3-4 people, opt for an indoor tankless unit with a BTU rating around 140,000 BTU and a lower flow rate.
- If you have a larger home with 5-7 fixtures and require the highest capacity for simultaneous hot water use, consider a powerful indoor tankless propane heater with a high BTU output (e.g., 199,000 BTU) and a flow rate of over 10 GPM.
Quick Best 40 Gallon Propane Water Heater Buying Checklist
- Check Manufacturer’s Warranty: Ensure adequate coverage for tank and parts.
- Verify First Hour Rating (FHR): Match FHR to your household’s peak usage needs.
- Understand Energy Factor (UEF): Look for higher UEF ratings for better efficiency.
- Assess Venting Requirements: Confirm compatibility with your installation location (direct-vent vs. atmospheric).
- Measure Installation Space: Ensure the unit’s dimensions fit your designated area.
- Consider Ignition Type: Piezo igniters are common; some have electronic ignition.
Frequently Asked Questions
What Is The Typical Lifespan Of A 40-Gallon Propane Water Heater?
A 40-gallon propane water heater typically lasts between 10 to 15 years with proper maintenance. Regular flushing of the tank and anode rod inspection can extend its operational life significantly, ensuring reliable hot water for your home.
How Does The First Hour Rating (Fhr) Affect Hot Water Availability?
The First Hour Rating (FHR) indicates how much hot water a heater can supply in the first 60 minutes of use. A higher FHR is crucial for households with high simultaneous demand, ensuring enough hot water for multiple uses without interruption.
What Are The Key Differences Between Direct-Vent And Atmospheric Vent Propane Water Heaters?
Direct-vent heaters draw combustion air from outside and vent exhaust outdoors through a single vent system, making them suitable for enclosed spaces. Atmospheric vent heaters use indoor air for combustion and vent through a chimney or flue, requiring proper ventilation.
Is A 40-Gallon Propane Water Heater Suitable For A Family Of Four?
Yes, a 40-gallon propane water heater is generally suitable for a family of four, especially if hot water usage is moderate. For higher demand households, a model with a higher First Hour Rating might be a better choice to ensure consistent hot water supply.
What Maintenance Is Required For A Propane Water Heater?
Essential maintenance includes flushing the tank annually to remove sediment, checking the anode rod for corrosion, and inspecting the vent system for blockages. These tasks help prevent damage and ensure efficient, safe operation of your heater.
Final Words
Choosing the best 40 gallon propane water heater ensures reliable and efficient hot water for your home’s needs, from showers to laundry. These units offer a robust supply of hot water, often without the need for electricity, providing flexibility and peace of mind. Investing in a quality propane water heater is a practical step towards consistent comfort and convenience.