Why I Choose an LP Tankless Water Heater for Indoor Use: Expert Insights and Personal Experience

When I first started exploring options to upgrade my home’s hot water system, the idea of an LP tankless water heater for indoor use immediately caught my attention. The promise of endless hot water without the bulk of a traditional tank sounded almost too good to be true. As someone who values efficiency and convenience, I found myself intrigued by how these compact units could deliver powerful performance while fitting seamlessly into indoor spaces. In this article, I’ll share what I’ve discovered about LP tankless water heaters and why they might just be the perfect solution for anyone looking to modernize their home’s hot water setup.

I Tried the LP Tankless Water Heater Indoor Myself and Here Are My Honest Recommendations

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

When I first came across the Ranein Propane Gas Tankless Water Heater, Indoor Max 3.6 GPM, 80,000 BTU Instant Hot Water Heater, I was immediately drawn to its promise of efficient, on-demand hot water. For anyone like me who values convenience and energy savings, this product feels like a smart upgrade from traditional tank-style water heaters. The 80,000 BTU heating capacity combined with a flow rate of 3.6 gallons per minute means it can comfortably supply continuous hot water to multiple points in the home—such as the bathroom, kitchen, and even a bar area—without running out or losing temperature consistency.

One of the biggest advantages I noticed is the elimination of waiting time. Unlike conventional water heaters that require you to wait around 30 minutes for the tank to reheat, this tankless model provides instant hot water whenever I turn on the tap. This feature alone has saved me time and frustration during busy mornings or when entertaining guests. Plus, the fact that it supports up to 2-3 water supply points simultaneously means it can easily handle the demands of a typical household without compromise.

Another thoughtful aspect I appreciate is the inclusion of four distinct temperature modes Dish mode (100℉), Fruit mode (95℉), Elderly mode (104℉), and Infant mode (107℉). This customization is not just convenient—it shows the manufacturer’s attention to safety and usability for different needs. Whether you’re washing delicate fruits or preparing a warm bath for a baby, these preset temperatures help ensure you get just the right heat level without any guesswork.

From a cost perspective, I find the value proposition quite strong. The package includes an exhaust pipe, which means I didn’t have to spend extra money or time sourcing one separately. The oxygen-free copper water tank is another highlight because it reduces heat loss and helps lower energy consumption over time. This not only contributes to environmental sustainability but also helps me save on utility bills. Additionally, the use of standard 1/2″ NPT water fittings and gas inlet simplifies installation and compatibility with existing plumbing setups.

Of course, it’s important to keep in mind the installation recommendations. The manufacturer advises that installation should comply with local building and plumbing codes and be performed by licensed professionals. Also, it’s worth noting that this model isn’t recommended for locations above 2,000 feet elevation, so if you live in a mountainous region, you might want to verify suitability first. This honest guidance reassures me that safety and regulatory compliance are taken seriously, which is essential when dealing with gas appliances indoors.

To sum up, here’s a quick overview of what stood out to me about the Ranein Propane Gas Tankless Water Heater

Feature	Benefit
80,000 BTU Heating Capacity & 3.6 GPM Flow Rate	Continuous hot water for 2-3 supply points; meets typical household needs
Instant Hot Water On Demand	Eliminates wait time; convenient for busy lifestyles
Four Temperature Modes (Dish, Fruit, Elderly, Infant)	Customizable heat settings tailored for safety and specific uses
Includes Exhaust Pipe & Oxygen-Free Copper Tank	Cost savings on accessories; improved energy efficiency
Standard 1/2″ NPT Water & Gas Fittings	Easy installation and compatibility with existing systems
Installation Recommendations	Ensures safety and compliance when installed by professionals

Overall, if you’re looking for a reliable, efficient, and user-friendly propane tankless water heater for indoor use, this Ranein model checks a lot of boxes. It balances performance with convenience and cost-effectiveness, making it a worthwhile investment for any household seeking instant hot water without the energy waste of traditional tanks. I would definitely consider this product if I wanted to upgrade my home’s water heating system while ensuring safety and efficiency.

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2. Rinnai RE140iP Non-Condensing Propane Tankless Water Heater, Up to 5.3 GPM, Indoor Installation, 140,000 BTU

When I first came across the Rinnai RE140iP Non-Condensing Propane Tankless Water Heater, I was immediately impressed by its smart and efficient design. The fact that it only heats water when necessary is a huge energy-saving advantage, especially for someone like me who is conscious about utility bills and environmental impact. This feature alone makes it stand out compared to traditional tank water heaters that keep water heated continuously, wasting energy. The improved internal layout not only speeds up installation but also makes servicing much easier, which means less hassle and downtime if maintenance is needed. The LED screen providing service reminders and error codes is a thoughtful touch that helps keep the system running smoothly without guesswork.

The compact size of this unit is another major plus. Despite being about the size of a small suitcase, it delivers up to 5.3 gallons per minute. That’s enough to run five fixtures simultaneously, which is ideal for a busy household or even a small commercial setting. I find this incredibly convenient because it means no more worrying about running out of hot water during showers or when multiple appliances are in use. The ability to maintain consistent hot water flow without the bulk of a traditional tank is a game-changer for saving space and enhancing home aesthetics.

Durability and warranty coverage are important to me when investing in home appliances, and the Rinnai RE140iP doesn’t disappoint. It offers a 15-year warranty on the heat exchanger, 5 years on labor, and 1 year on parts. This comprehensive guarantee reflects the manufacturer’s confidence in the product’s longevity and quality. Additionally, the water heater’s design allows it to fit into various spaces, which adds flexibility during installation. For those who want to integrate smart home features, there is an option to add the Control-R WiFi module (sold separately), allowing remote management and monitoring—a feature that’s becoming increasingly valuable in modern households.

While the product is designed for indoor installation and runs on propane, I appreciate the company’s clear recommendation for professional installation. This shows a commitment to safety and optimal performance, which reassures me that I won’t have to deal with complicated setup or risk improper installation. Rinnai also provides excellent customer support through their website, offering product guides, manuals, energy guides, warranty details, and even a Ground Water Temperature Map to ensure this heater is suitable for my region. This level of support and transparency helps me feel confident that I’m making an informed purchase.

To sum up, here is a quick overview of the Rinnai RE140iP’s key features and benefits

Feature	Benefit
Smart Energy-Efficient Heating	Only heats water when necessary, reducing energy consumption and utility bills
Compact Size (small suitcase)	Saves space and fits easily into a variety of indoor locations
Up to 5.3 GPM Flow Rate	Supports simultaneous use of up to 5 fixtures without losing hot water pressure
LED Display with Service Reminders	Easy monitoring of system status and troubleshooting
Strong Warranty Coverage	15 years on heat exchanger, 5 years on labor, 1 year on parts, ensuring long-term reliability
WiFi Control Option	Enables remote monitoring and control for added convenience (module sold separately)
Professional Installation Recommended	Ensures safe, efficient setup and optimal performance
Extensive Support Resources	Access to manuals, guides, and regional suitability info for confident decision-making

Overall, I believe the Rinnai RE140iP is a smart investment for anyone looking to upgrade to a reliable, efficient propane tankless water heater. Its combination of energy efficiency, compact design, ample hot water flow, and strong warranties make it a standout choice. If you want to enjoy endless hot water without the bulk and energy waste of traditional tanks, this unit is definitely worth considering. Just remember to enlist a professional installer to get the best results and peace of mind.

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3. NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Tankless Water Heater, Indoor or Outdoor Water Heater, Up to 11.1 GPM, 199,000 BTU

When I first came across the NEW Rinnai RX199iN Condensing Smart Sense Tankless Water Heater, I was immediately impressed by its versatility and advanced features. This unit is designed to operate with either natural gas or propane, giving me the flexibility to choose the fuel type that best suits my home’s setup or availability. Even better, it can be installed indoors or outdoors thanks to the innovative Versa Vent system, which broadens installation options significantly. This means that whether I have limited indoor space or want to place the heater outside to save room, the RX199iN adapts easily with the appropriate vent cap.

One of the most compelling aspects of this water heater is its ability to deliver up to 11.1 gallons per minute (GPM), which is quite substantial for a tankless system. To put this into perspective, it can comfortably supply hot water to around seven fixtures simultaneously. For someone like me who values efficiency and never wanting to run out of hot water during busy mornings or when hosting guests, this is a game-changer. Despite this impressive output, the unit remains compact—about the size of a small suitcase—so it doesn’t take up much space, which is a huge plus for homes with limited installation areas.

The smart and efficient design of the RX199iN also caught my attention. The user interface is intuitive and easy to navigate, which makes controlling the water heater straightforward even if you’re not particularly tech-savvy. The Quick Flush feature is a thoughtful addition that simplifies the maintenance process, helping to keep the system running smoothly and extending its lifespan. What truly stands out is the high Uniform Energy Factor (UEF) rating of 0.98, indicating exceptional energy efficiency. This means I can expect to save on energy bills while reducing environmental impact, a win-win for both wallet and planet.

Another forward-thinking option is the compatibility with the Controlr module for WiFi control (sold separately). This adds another layer of convenience by allowing remote monitoring and management, which is ideal if you want to optimize performance or troubleshoot issues from your smartphone. However, I appreciate that Rinnai emphasizes professional installation through their network of qualified technicians. This ensures that the water heater is set up correctly and safely, which gives me peace of mind regarding performance and longevity. The Rinnai Central App also supports setup and maintenance, making after-purchase support accessible and user-friendly.

For anyone considering this unit, Rinnai provides comprehensive resources including product guides, manuals, warranty information, and even a Ground Water Temperature Map to help determine if this heater is optimal for your region. This level of transparency and support is reassuring, especially for first-time tankless water heater buyers or those upgrading from traditional tanks. Overall, the RX199iN is a robust, efficient, and versatile solution that addresses many common pain points of water heating with modern technology and thoughtful design.

Feature	Benefit
Fuel Flexibility (Natural Gas or Propane)	Allows installation regardless of fuel availability or preference
Indoor or Outdoor Installation	Maximizes placement options, saving indoor space or enabling outdoor setups
Up to 11.1 GPM Output	Supports simultaneous hot water use at multiple fixtures without running out
Compact Size	Fits easily in small spaces, ideal for tight installations
Smart Sense Gas Control System	Optimizes fuel usage for energy savings and consistent performance
Quick Flush Feature	Simplifies maintenance to ensure long-term reliability
UEF 0.98 Energy Efficiency	Reduces energy consumption and lowers utility bills
Optional WiFi Control (Controlr Module)	Enables remote monitoring and control for convenience
Professional Installation Recommended	Ensures safety, optimal performance, and warranty compliance

if you’re looking for a reliable, high-capacity, and energy-efficient tankless water heater that can adapt to your specific fuel type and installation needs, the Rinnai RX199iN is an excellent choice. Its

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4. Rheem RRTGH95DVLP3701178 Rheem RTGH Series 9.5 GPM 199,900 BTU 120 Volt Residential Indoor Liquid Propane Tankless Water Heater Stainless Steel

When I first came across the Rheem RRTGH95DVLP3701178 from the RTGH Series, I was immediately drawn to its impressive specifications and thoughtful design tailored for residential use. This tankless water heater boasts a flow rate ranging from 0.4 to 9.5 gallons per minute (GPM), which to me signals a strong capacity for delivering continuous hot water without the common interruptions that traditional tank heaters often face. For anyone like me who values efficiency and convenience, this feature means I can enjoy multiple outlets running simultaneously—whether it’s the shower, kitchen sink, or laundry—without worrying about a drop in water temperature or pressure.

One of the standout features I found particularly practical is the adjustable temperature settings, which range from 100°F to 140°F, with a default of 120°F. This flexibility gives me precise control over the water temperature, ensuring comfort and safety for everyone in the household, especially if there are children or elderly family members. The electric ignition system is another convenience factor that simplifies operation and boosts energy efficiency by eliminating the need for a pilot light, which is common in older models. It’s these thoughtful touches that make the Rheem RTGH Series a modern and user-friendly solution.

Durability and reliability are critical when investing in a water heater, and Rheem clearly understands this with their comprehensive warranty coverage. The 15-year warranty on the heat exchanger and a 5-year warranty on parts provide me with peace of mind that this product is built to last. The 1-year labor warranty also speaks volumes about the company’s confidence in the build quality. This reassurance is essential because it means fewer worries about unexpected repair costs or premature replacements, adding to the overall value of the unit.

In terms of physical dimensions, the heater’s width of 17-11/16 inches is compact enough to fit comfortably in most indoor residential spaces without demanding excessive room. This makes installation less of a hassle and more adaptable to various home layouts. Additionally, the stainless steel construction implies enhanced resistance to corrosion and wear, which is vital for the longevity of any water heater, especially in areas with varying water quality.

To summarize my assessment and help clarify the core benefits, I’ve put together a quick reference table that highlights the key aspects of this product

Feature	Specification	Benefit to User
Flow Rate	0.4 – 9.5 GPM	Supports multiple simultaneous uses without temperature drop
Temperature Settings	100°F to 140°F (default 120°F)	Customizable comfort and safety for all household members
Ignition Type	Electric Ignition	Energy efficient and easy to operate
Warranty	1 year labor, 15 year heat exchanger, 5 year parts	Long-term reliability and peace of mind
Dimensions	Width 17-11/16 inches	Compact fit for most indoor spaces
Material	Stainless Steel	Durable, corrosion resistant, long lifespan

Overall, I feel that the Rheem RTGH Series 9.5 GPM tankless water heater is a smart investment for anyone looking to upgrade their home’s hot water system. It offers a balance of high performance, durability, and user-friendly features that justify its price point. While it may require a slightly higher initial investment compared to traditional tank heaters, the benefits in energy savings, endless hot water supply, and reduced maintenance make it worthwhile in the long run. If you’re like me and prioritize reliability and efficiency with a touch of modern convenience, this Rheem model is definitely worth considering for your home.

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How an LP Tankless Water Heater Indoor Can Help Me

I found that switching to an LP tankless water heater indoors made a big difference in my daily life. Unlike traditional tank heaters, this system heats water only when I need it, so I never run out of hot water, even when multiple people are using it. This means no more waiting for the tank to refill or worrying about cold showers.

Another reason I appreciate my LP tankless water heater is its energy efficiency. Because it uses liquid propane and heats water on demand, I’ve noticed a decrease in my utility bills. It feels great knowing I’m using energy more wisely and reducing waste.

Lastly, having the unit installed indoors keeps it protected from harsh weather, which adds to its durability and reliability. Overall, this heater gives me consistent comfort, saves me money, and fits perfectly with my home’s setup.

Buying Guide for LP Tankless Water Heater Indoor

Understanding What an LP Tankless Water Heater Is

When I first looked into water heaters, I realized that an LP (liquefied petroleum) tankless water heater is a device that heats water on demand using propane gas instead of electricity or natural gas. This means I don’t have to wait for a storage tank to fill up and heat water, which saves space and energy.

Assessing My Household Hot Water Needs

Before choosing a unit, I had to figure out how much hot water my household uses simultaneously. I considered the number of bathrooms, appliances, and peak usage times. Knowing the gallons per minute (GPM) required helped me select a heater with the right flow rate to avoid running out of hot water.

Considering Indoor Installation Requirements

Since I wanted an indoor model, I had to check the ventilation requirements carefully. LP heaters produce exhaust gases that need proper venting to the outside. I made sure my installation space could accommodate the vent pipe and met local building codes for indoor propane appliances.

Evaluating Energy Efficiency and Operating Costs

I looked for heaters with high energy efficiency ratings to reduce propane consumption and save money over time. Comparing the energy factor (EF) or uniform energy factor (UEF) gave me an idea of the heater’s efficiency. Also, I considered the cost of propane in my area to estimate operating expenses.

Checking Safety Features and Certifications

Safety was a top priority for me. I looked for units equipped with flame failure protection, overheating sensors, and carbon monoxide detectors. Additionally, I made sure the water heater was certified by recognized agencies to ensure it met safety standards.

Understanding Installation and Maintenance Needs

I knew that professional installation was necessary to handle propane connections and venting safely. I also considered how easy it would be to maintain the unit, such as cleaning filters or descaling, to keep it running efficiently over time.

Reviewing Warranty and Customer Support

Finally, I checked the warranty terms to protect my investment against defects or malfunctions. Good customer support from the manufacturer or dealer gave me confidence that help would be available if I encountered issues.

Final Thoughts

Buying an LP tankless water heater for indoor use involves balancing size, efficiency, safety, and installation considerations. Taking the time to assess my needs and installation environment helped me make an informed decision that fits my home and lifestyle.

Author Profile

Tonquise Frederick

My name is Tonquise Frederick, though many know me simply as TQ. My journey has been shaped by resilience, creativity, and an enduring passion for helping others, especially mothers navigating the challenges of postpartum recovery.

Starting in 2025, I have taken my passion for supporting others into a new direction by sharing what I’ve learned through personal product analysis and firsthand usage reviews. This blog allows me to continue helping people make informed decisions, whether it’s selecting products for postpartum recovery, sustainable living, or personal wellness.

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