For shoppers searching for natural gas hot water tanks, these five tankless models offer on-demand alternatives without a storage tank. The Rinnai RE199iN is best for high-demand indoor use, while the Rinnai REP199iN adds built-in recirculation to help reduce hot-water wait times. The Rheem is an outdoor option, and the 5.26 GPM model is suited to more modest demand. Compare installation location, flow rate, and household hot-water needs before choosing.
| Product | Best suited for | Listed capacity |
|---|---|---|
| Rinnai RE199iN | High-demand indoor use | Up to 9.8 GPM |
| Rheem RTG Series | Outdoor installation | 8.4 GPM |
| Rinnai REP199iN | Reducing hot-water wait times | 7.9 GPM |
| Natural Gas 5.26 GPM model | Lower-demand outdoor use | 5.26 GPM |
| Ranein 8.5 GPM | Indoor use with multiple water points | 8.5 GPM |
Rinnai RE199iN: Best for High-Demand Indoor Use
This indoor, non-condensing model is listed at 199,000 BTU and up to 9.8 gallons per minute. Its stated capacity and whole-house positioning make it the best fit here for households with several potential hot-water demands, such as showers, laundry, and dishwashing. Actual simultaneous flow depends on conditions at the home, so match the unit to local climate and fixture demand rather than relying on the maximum figure alone.
The wall-mounted design saves floor space. An LED display provides diagnostic codes and service reminders. The product listing gives a 15-year limited heat-exchanger warranty, five years on parts, and one year on labor. Wi-Fi monitoring requires a separately sold Controlr module. Choose this if you want an indoor unit with high listed flow; avoid it if you need built-in recirculation, which the listing identifies on another model.
Rheem RTG Series: Best for Outdoor Installation
The Rheem RTG Series is an outdoor, non-condensing natural gas tankless water heater rated at 180,000 BTU and 8.4 GPM in its product name. It is best for buyers who specifically want an outdoor unit and have household demand that fits its stated flow rate. Compared with the indoor Rinnai RE199iN, its distinguishing choice is the listed outdoor installation location.
The supplied product information does not provide further feature details, installation requirements, or warranty terms. Confirm the exact model specifications and suitability for your home before buying. Avoid this choice if you need an indoor-mounted heater or require more flow than its stated rating can support.
Rinnai REP199iN: Best for Shorter Waits
This indoor Rinnai model is rated at 199,000 BTU and up to 7.9 GPM. Its built-in recirculation pump is intended to help reduce hot-water wait times, making it the best match for buyers who prioritize quicker hot water at fixtures. It provides on-demand heating in a compact, space-saving design.
Its listed maximum flow is lower than the RE199iN’s 9.8 GPM, so compare both ratings against simultaneous household use. Choose this model if built-in recirculation matters more than the higher stated flow of the RE199iN. Confirm installation requirements for the home with a qualified professional.
5.26 GPM Model: Best for Lower Demand
This outdoor natural gas model is listed at 5.26 GPM, with a Fahrenheit digital display and multi-protection features. It is best for buyers whose hot-water demand fits a lower listed flow rate and who are looking for an outdoor unit. The display may help users read the temperature setting in Fahrenheit.
Its stated capacity is below the other models in this comparison, so it may be a poor fit for households that often run multiple hot-water fixtures at once. The product name does not specify BTU output or detailed installation requirements. Verify those details before purchase.
Ranein 8.5 GPM: Best for Multiple Water Points
The Ranein indoor tankless model is listed at 8.5 GPM and 190,000 BTU. Its description positions it for a large home and four to six water points, so it is best for buyers seeking a high-flow indoor option. Listed features include a wall-mounted compact design, LED display, anti-freeze function, and standard 3/4-inch NPT water inlet fittings.
The product description also mentions an adjustable blower and says it helps provide oxygen for combustion. Installation still needs to match the home’s gas, venting, and plumbing requirements. Although the listing describes quick assembly, buyers should not assume that professional installation is unnecessary.
Buying Guide: How to Choose a Natural Gas Tankless Heater
How much flow rate does a household need?
Estimate which hot-water fixtures may operate at the same time, then compare that demand with each model’s listed GPM. A higher maximum figure does not guarantee the same flow in every home: incoming water temperature and other installation conditions can affect delivered hot water. Consider the 5.26 GPM model for lower demand; compare the 8.4–9.8 GPM options for higher stated capacity.
Should the unit be installed indoors or outdoors?
Choose based on the manufacturer’s specified installation location and the home’s layout. The RE199iN, REP199iN, and Ranein models are listed as indoor units, while the Rheem and 5.26 GPM models are identified as outdoor units. Do not assume an indoor model can be installed outdoors or vice versa. Review local code and installation instructions with a qualified professional.
Is recirculation important?
A built-in recirculation pump is the defining feature of the Rinnai REP199iN in this selection. It is designed to help reduce the wait for hot water. If you do not need that feature, compare the other models by location and listed GPM instead. Also distinguish built-in features from accessories sold separately, such as the RE199iN’s optional Controlr module.
What should buyers verify before ordering?
Confirm fuel type, gas supply, venting, clearances, electrical needs, water connections, and local installation rules against the exact model documentation. Check the warranty terms directly for the model being considered. Tankless heaters do not store a tankful of heated water, but their output is limited by capacity and operating conditions.
Frequently Asked Questions
Are these traditional natural gas hot water tanks?
No. These products are tankless water heaters that heat water on demand rather than storing it in a traditional tank.
Which model has the highest listed flow rate?
The Rinnai RE199iN has the highest listed rate in this selection, at up to 9.8 GPM.
Which model has built-in recirculation?
The Rinnai REP199iN is listed with a built-in recirculation pump intended to help reduce hot-water wait times.
Can a tankless heater supply several fixtures at once?
It can serve simultaneous demand within its capacity, but actual output depends on the model and operating conditions. Compare expected fixture demand with the heater’s flow rating.
Is an outdoor model right for every home?
No. Outdoor installation depends on the model’s specifications, local conditions, and applicable installation requirements. Confirm suitability before buying.