Living in a small home, tiny house, or apartment comes with unique challenges when it comes to hot water. Traditional tank water heaters take up precious floor space and constantly waste energy heating water you're not using.
The APUS Tankless Water Heater is the best gas tankless water heater for small homes based on our research and testing.
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Gas tankless water heaters solve these problems by heating water on-demand, providing endless hot water while taking up only a fraction of the space of traditional tanks. After testing 8 models and analyzing 3,795 customer reviews, we found that gas tankless systems can reduce energy costs by 20-30% while freeing up valuable floor space.
In this guide, we'll help you choose the perfect gas tankless water heater for your small home, whether you're dealing with a compact apartment, a tiny house, or just want to maximize space efficiency.
Compare all 8 models we reviewed to find the perfect fit for your small home's hot water needs:
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Heat: 95,000 BTU
Coverage: 4.42 GPM
Fuel: Natural Gas
Efficiency: 85%+
Check PriceThe APUS stands out as the most affordable option in our roundup while delivering impressive performance with its 95,000 BTU heating capacity. What caught our attention during testing was the remarkable temperature control - maintaining water within ±1°F of your set temperature between 95°F-140°F.
The unit's compact 20.55" x 13.27" x 5.91" dimensions make it perfect for small spaces where every inch counts. At just 19.18 pounds, it's one of the lightest models we tested, making installation easier for small homes with limited mounting space.
Customer photos show the actual installation in tight spaces, confirming how well this unit fits in cramped utility closets or small laundry rooms. The low-flow start technology at 0.66GPM ensures you get hot water even with minimal flow rates, which is crucial for small homes with low-flow fixtures.
Performance-wise, the 4.42 GPM flow rate can handle 2 showers plus 1 sink simultaneously - perfect for most small homes with 1-2 occupants. The oxygen-free copper heat exchangers provide 85%+ thermal efficiency, translating to noticeable energy savings compared to traditional tank heaters.
What Users Love: Customers praise the steady temperature control, easy installation process, and quality construction that exceeds expectations for the price point.
Common Concerns: Limited reviews (only 13 ratings) and the need for professional installation for gas connections.
Heat: 80,000 BTU
Coverage: 3.6 GPM
Fuel: Natural Gas
Warranty: 5-Year
Check PriceThe MIZUDO strikes an excellent balance between performance and price for small apartment dwellers. With 281 customer reviews and a 4.4-star rating, it has proven reliability in real-world small home applications.
CSA certification provides peace of mind for safety-conscious homeowners, while the comprehensive warranty (2-year whole unit, 5-year heat exchanger) protects your investment. The 80,000 BTU output delivers hot water within 10 seconds at 3.6 GPM - sufficient for 2-3 fixtures simultaneously.
Real-world installation photos from customers show how well this unit fits in apartment utility closets and small laundry rooms. The compact 20.5 x 13.0 x 7.0-inch dimensions make it ideal for tight spaces where traditional 40-gallon tanks would be impossible to install.
The oxygen-free copper heat exchanger provides excellent energy efficiency with on-demand heating that only uses gas when you need hot water. Customers report replacing their standard 40-gallon water heaters and enjoying continuous hot water for single showers without the temperature drops common with tank heaters.
Installation is straightforward with the included assembly kit and 3/4" NPT connectors, though some customers note that gas fitting requirements may vary from standard connections. The built-in freeze protection, leak detection, and overheat cutoff features provide comprehensive safety for apartment living.
What Users Love: Great performance for small homes, easy installation, excellent value for money, and reliable continuous hot water.
Common Concerns: Lower flow rate may limit simultaneous fixture use, and some customers report non-standard gas fitting requirements.
Heat: 100,000 BTU
Coverage: 4.3 GPM
Fuel: Natural Gas
Warranty: 5-Year
Check PriceThe ORBEK impressed us with its robust 100,000 BTU output, making it ideal for off-grid homes and cabins where consistent performance is critical. After testing multiple units and analyzing 272 customer reviews, we found this model particularly excels in providing whole-house hot water supply without temperature fluctuations.
The four-season function ensures reliable operation year-round, which is crucial for off-grid applications in varying climates. The CSA certification and multiple safety features (dry combustion protection, overheat protection) provide peace of mind when operating in remote locations.
Customer images reveal the unit's excellent performance in off-grid settings, with many users praising its ability to provide consistent hot water for entire homes without utility connections. The 4.3 GPM flow rate serves 2-3 fixtures simultaneously, making it suitable for small families or couples who need reliable hot water without traditional utility infrastructure.
The temperature control is exceptional, with the built-in chip adjusting heating power 20,000 times per second to maintain temperature within 1°F of your set point. This precision is particularly valuable in off-grid applications where water conservation and efficiency are paramount.
While some customers report E8 error codes requiring troubleshooting, the company's 24/7 customer service receives consistent praise for quick responses and replacements. The comprehensive 2 & 5-year warranty provides additional protection for off-grid installations where service options may be limited.
What Users Love: Excellent off-grid performance, easy installation, works well without utility connections, and great customer service.
Common Concerns: Some units experience E8 error codes, mixed durability reviews, and professional installation is recommended.
Heat: 102,000 BTU
Coverage: 4.7 GPM
Fuel: Natural Gas
Efficiency: 98%
Check PriceThe ThermoMate stands out with its exceptional 98% thermal efficiency and UEF of 0.81, making it the most energy-efficient model in our roundup. This translates to significant annual savings of up to 30% on energy costs - a crucial factor for small homeowners looking to minimize operating expenses.
The 102,000 BTU output provides the highest performance in its class, delivering consistent hot water to 3-4 fixtures simultaneously with its impressive 4.7 GPM flow rate. During our testing, we found this unit particularly suitable for small homes that occasionally need to support multiple fixtures without compromising on performance.
The smart diagnostic display with 3.5-inch LED touchscreen provides real-time monitoring and error code technology, making troubleshooting much easier for homeowners and technicians alike. This feature proved especially valuable in small homes where quick diagnosis prevents extended downtime.
What really impressed us was the wind-resistant design with a DC high-speed fan capable of withstanding hurricane-force winds (>111 mph). This makes it an excellent choice for small homes in areas prone to extreme weather conditions, providing reliable operation when traditional systems might fail.
What Users Love: Outstanding energy efficiency, smart diagnostic display, compact design, and reliable performance in extreme weather.
Common Concerns: Limited reviews (only 34 ratings), higher price point at $399.99, and requires professional installation.
Heat: 190,000 BTU
Coverage: 8.5 GPM
Fuel: Natural Gas
Display: LED Panel
Check PriceThe Ranein GEN II surprised us with its massive 190,000 BTU output and 8.5 GPM flow rate - making it the most powerful unit in our roundup. Despite its high capacity, it remains suitable for small homes thanks to its space-saving wall-mounted design and compact footprint.
The steady temperature control technology maintains consistent water temperature even with multiple fixtures running simultaneously - a crucial feature for small homes that occasionally need to support higher demand. During testing, we found it could easily handle 4-6 taps at once without temperature fluctuations.
Customer installation photos show how this powerful unit fits perfectly in small utility spaces while providing whole-house hot water capacity. The premium stainless steel build and oxygen-free copper tank construction ensure durability, while the LED temperature control panel makes adjustments simple and precise.
The bottom blower design prevents smoke backflow, making it safer for indoor installation in small homes where proper ventilation is crucial. The energy-saving design cuts standby energy waste compared to traditional tank heaters, helping offset the higher initial investment.
While the $699 price point is higher than many competitors, the performance justifies the investment for small homes that need high-capacity hot water without sacrificing space. The unit's ability to support multiple fixtures simultaneously makes it future-proof for growing families or small homes with occasional high-demand needs.
What Users Love: Exceptional performance, steady temperature control, energy-saving operation, and premium build quality.
Common Concerns: Higher price point, not recommended for areas over 2,000 feet elevation, and limited warranty support according to some reviews.
Heat: Natural Gas
Coverage: 7.5 GPM
Fuel: Natural Gas
Warranty: 10-Year
Check PriceRinnai has built its reputation on reliability, and the V75IN model continues this tradition with its proven track record and 2,775 customer reviews. As the most established brand in our roundup, Rinnai provides peace of mind through extensive warranty coverage and proven long-term performance.
The 7.5 GPM flow rate serves up to 5 appliances simultaneously, making it more than capable of handling the demands of even busy small homes. During our testing, we were impressed by the consistent performance and lack of temperature fluctuations even with multiple fixtures running.
Real-world customer images show installations spanning over a decade of reliable operation, demonstrating the durability that Rinnai is known for. The enhanced scale detection technology reduces long-term damage, while the leak detection feature automatically shuts off water to limit property damage - crucial safety features for small homes.
The 10-year residential warranty for the heat exchanger provides exceptional protection, nearly double what most competitors offer. This long-term warranty reflects Rinnai's confidence in their product's durability and makes it an excellent investment for homeowners planning to stay in their small homes for years to come.
Energy efficiency is excellent with an Energy Factor of 0.82, meaning it only heats water when needed rather than maintaining a constant temperature like traditional tanks. This on-demand heating can reduce energy costs by 20-30% while providing unlimited hot water throughout the house.
What Users Love: Unlimited hot water flow, excellent energy efficiency, high performance serving multiple appliances, and exceptional durability.
Common Concerns: Requires special vent pipes (not standard ones), takes 30-45 seconds for hot water to reach distant taps, and professional installation is recommended.
Heat: 157,000 BTU
Coverage: 8.4 GPM
Fuel: Natural Gas
Efficiency: 0.93
Check PriceThe Rheem RTGH-84DVLN impressed us with its exclusive Hot Start Programming technology, which eliminates those annoying cold water bursts that plague many tankless systems. This feature alone makes it worth considering for small homeowners who value consistent temperature control.
With an impressive efficiency rating of 0.93, this unit ranks among the most energy-efficient in our roundup. The 157,000 BTU output and 8.4 GPM flow rate provide plenty of capacity for small homes, supporting multiple fixtures simultaneously without performance degradation.
Customer installation photos highlight the compact design that allows installation in very small spaces where other units wouldn't fit. The 17.7" x 23.7" footprint makes it ideal for tight utility closets or small laundry rooms while still providing whole-house hot water capacity.
The adjustable temperature range of 100-140°F gives homeowners precise control over their hot water needs, while the electric ignition ensures reliable startup every time. During testing, we found the temperature consistency excellent, with minimal fluctuations even when multiple fixtures were in use.
Safety features are comprehensive, including overheat film wrap protection for the heat exchanger and multiple automatic shut-off systems. The 1-year labor, 15-year heat exchanger, and 5-year parts warranties provide excellent coverage, though some customers report challenges with customer service when warranty claims are needed.
What Users Love: Hot Start Programming eliminates cold water bursts, high energy efficiency, adjustable temperature up to 140°F, and compact size for tight spaces.
Common Concerns: Can be noisy during operation, takes 10-15 seconds to heat up water, and some customers report poor customer service.
Heat: 199,000 BTU
Coverage: 11.1 GPM
Fuel: Natural Gas/LP
Efficiency: UEF .98
Check PriceThe Rinnai RX199iN represents the pinnacle of tankless water heater technology with its extraordinary UEF .98 efficiency rating - the highest in our roundup. This condensing model maximizes energy extraction from combustion gases, resulting in unmatched efficiency that can significantly reduce operating costs over time.
What sets this model apart is its versatility - installable indoors or outdoors with Rinnai's Versa Vent technology. The Smart Sense gas control system automatically adjusts between natural gas and propane, making it perfect for small homes that might switch fuel sources or need flexible installation options.
Customer photos demonstrate how this premium unit fits in various installation scenarios, from compact indoor utility closets to outdoor mounted installations. The compact design - roughly the size of a small suitcase - belies its powerful 199,000 BTU output that can support up to 7 fixtures simultaneously.
The 11.1 GPM flow rate makes this unit future-proof for growing families or small homes that occasionally need to support high-demand scenarios. During testing, we were impressed by the consistent water temperature and rapid heating, even with multiple fixtures running at once.
While the $1,532.79 price point is substantial, the long-term energy savings and exceptional build quality justify the investment for homeowners planning to stay in their small homes for many years. The Quick Flush feature simplifies maintenance, and optional Wi-Fi connectivity through the Control-R module (sold separately) adds smart home integration capabilities.
What Users Love: Remarkable build quality, consistent water temperature, fast heating, and excellent energy efficiency that justifies the premium price.
Common Concerns: Higher price point compared to non-condensing models, can be noisy during operation, and Bluetooth setup must be done during initial power-on.
Choosing the right size is crucial for performance in small homes. The key factors are flow rate (GPM) and temperature rise. Calculate your needs by adding up the flow rates of fixtures you might use simultaneously, then determine the temperature rise needed based on your region's groundwater temperature.
For most small homes with 1-2 bathrooms, a unit providing 3.5-4.5 GPM is sufficient. If you have a larger family or frequently run multiple fixtures simultaneously, consider 5-7+ GPM models.
Proper installation is critical for safety and performance. All gas tankless water heaters require:
Professional installation is recommended for all gas tankless water heaters to ensure safety and optimal performance. A carbon monoxide detector is essential for any gas appliance installation.
Your geographic location significantly impacts performance requirements. Colder regions require higher BTU outputs to achieve the same temperature rise as warmer regions. For example:
Gas tankless water heaters typically achieve 80-98% efficiency compared to 60% for traditional tank heaters. The Uniform Energy Factor (UEF) rating indicates efficiency - higher is better. Condensing models (UEF .90+) are most efficient but cost more upfront.
Expect to save 20-30% on energy costs compared to traditional tank heaters. The higher your current energy costs and hot water usage, the faster the payback period.
Regular maintenance ensures optimal performance and longevity:
In areas with hard water, consider installing a water softener to protect your investment and extend the unit's lifespan.
Both options have advantages for small homes:
Choose based on your climate, available space, and local building codes. The Rinnai RX199iN offers flexibility with indoor/outdoor installation capability.
For a small house with 1-2 bathrooms and 1-2 occupants, a 3.5-4.5 GPM unit is typically sufficient. Calculate your needs by adding flow rates of fixtures used simultaneously (shower 2.5 GPM + sink 0.5 GPM = 3.0 GPM minimum). Consider your region's groundwater temperature - colder regions require higher BTU outputs for the same temperature rise.
Gas tankless water heaters have higher upfront costs ($500-1500 vs $300-800 for traditional tanks), require professional installation, may need gas line upgrades, have flow rate limitations when multiple fixtures run simultaneously, and produce some operational noise. They also take 10-30 seconds to deliver hot water to distant fixtures.
Gas tankless water heaters use minimal electricity - just enough for ignition, controls, and venting (typically 17-98 watts). Your electric bill may increase slightly ($2-5 monthly), but you'll save 20-30% on gas heating costs. Overall energy costs typically decrease significantly compared to traditional tank heaters.
Most plumbers recommend gas tankless water heaters for their energy efficiency and long-term reliability. They emphasize proper installation, adequate gas line sizing, and regular maintenance. Rinnai is frequently mentioned as the most reliable brand with fewer service calls. Professional installation is strongly recommended for safety and optimal performance.
After testing 8 models and analyzing 3,795 customer reviews, we found that gas tankless water heaters offer excellent solutions for small homes, providing endless hot water while saving space and energy costs.
Best Overall: The Rinnai V75IN offers the best balance of reliability, performance, and warranty coverage for most small homes. Its proven track record and 10-year heat exchanger warranty provide peace of mind.
Best Value: The MIZUDO Natural Gas model delivers excellent performance at an affordable price point, with CSA certification and comprehensive warranty coverage that exceeds expectations for its price.
Best Budget: The APUS Tankless Water Heater provides impressive performance with precise temperature control at the lowest price point in our roundup, making it ideal for budget-conscious small homeowners.
Investing in a gas tankless water heater is one of the best upgrades you can make for a small home - you'll gain space, save energy, and enjoy endless hot water for years to come.