If you’re shopping for a gas water heater, the first thing to know is that the products below are tankless models—not conventional storage-tank heaters labeled as power vent. Several use direct venting or outdoor installation instead. That difference matters: check your home’s fuel type, venting setup, hot-water demand, and installation space before choosing a model.
Our comparison focuses on five gas tankless options, from compact indoor units to high-capacity models designed to serve several fixtures at once. Use the flow rate as a starting point, not a guarantee: the amount of hot water available at once also depends on incoming water temperature and your home’s setup.
Table of Contents
Quick Comparison
| Product | Fuel and installation | Listed flow rate | Notable feature |
|---|---|---|---|
| Rheem RTGH 9.0 GPM Indoor Tankless | Natural gas, indoor, direct vent | 9.0 GPM at a 35°F rise | Condensing design; 0.93 UEF |
| Rinnai RX199iN Smart Sense Tankless | Natural gas or propane; indoor or outdoor with required outdoor vent cap | Up to 11.1 GPM | 0.98 UEF; indoor/outdoor flexibility |
| Rheem RTG 7.0 GPM Indoor Tankless | Natural gas, indoor, direct vent | 7.0 GPM at a 35°F rise | Non-condensing design; leak detection |
| Rheem Prestige Tankless with Recirculation | Natural gas, indoor | 11.0 GPM | Built-in recirculation and auto-learn programming |
| Rheem RTG 7.0 GPM Outdoor Propane Tankless | Propane, outdoor | 7.0 GPM at a 35°F rise | Outdoor cabinet eliminates the need for indoor venting |
Our Picks: Best Power Vent Gas Water Heater reviews
1. Rheem RTGH 9.0 GPM: High-Capacity Indoor Condensing Model
The Rheem RTGH is a natural-gas tankless water heater for indoor installation. Its listed capacity is 9.0 gallons per minute at a 35°F temperature rise, with a 180,000 BTU-per-hour input. Rheem describes it as a condensing model with a 0.93 Uniform Energy Factor (UEF).
That combination makes it a strong fit for a household that needs more capacity than a smaller tankless unit can provide. Rheem says it is suited to three or four simultaneous showers, but actual performance depends on the temperature of incoming water and the number of fixtures running. The digital control adjusts temperature in 1°F increments, and the unit includes built-in freeze protection and multiple safety features.
This is an indoor direct-vent model, not a conventional power-vent tank heater. Its high capacity may suit a larger home, but choosing it based on flow rate alone would be a mistake. Have a qualified installer confirm that your gas supply, venting plan, and hot-water demand match the unit. The listed warranty is 15 years for the heat exchanger and five years for parts.
Pros:
- High listed output of 9.0 GPM at a 35°F rise
- Condensing design with a listed 0.93 UEF
- Indoor direct-vent configuration
- Digital temperature adjustment in 1°F increments
Cons:
- Uses natural gas, so it is not a match for propane-only homes
- Requires indoor installation and a compatible direct-vent setup
Verdict: Choose this Rheem if you need a high-capacity indoor natural-gas tankless unit and its direct-vent requirements suit your home.
2. Rinnai RX199iN: Flexible Fuel and Installation Options
The Rinnai RX199iN is a condensing tankless model with a listed maximum output of 11.1 GPM and a 199,000 BTU input. Its Smart Sense gas control supports natural gas or propane, while its Versa Vent design allows indoor or outdoor installation. An RX-OVC vent cap is required for outdoor installation.
Its listed 0.98 UEF is the highest among the models in this comparison that provide a UEF figure. Rinnai also lists a Quick Flush feature for simplified flushing and describes the unit as compact. The high stated flow rate may make it worth considering for homes with several hot-water fixtures, though the best match depends on local incoming-water temperatures and a professional sizing check.
The flexibility is useful, but it does not remove the need to confirm the exact installation configuration. The Wi-Fi control module is not included, so don’t assume remote app control comes with the heater. Rinnai recommends professional installation. Its listed residential warranty includes 15 years on the heat exchanger and five years on parts; the five-year labor coverage requires registration within 90 days of installation, or labor coverage defaults to one year.
Pros:
- Supports natural gas or propane
- Can be installed indoors or outdoors with the required outdoor vent cap
- Listed capacity reaches 11.1 GPM, with a 0.98 UEF
- Includes a Quick Flush feature
Cons:
- The outdoor vent cap is required for outdoor installation
- The Wi-Fi control module is sold separately
Verdict: The RX199iN is the most adaptable pick here if you need fuel flexibility, installation options, and high listed capacity—and are prepared to confirm the correct configuration with a professional.
3. Rheem RTG 7.0 GPM: Indoor Natural-Gas Value Option
This Rheem RTG is an indoor, natural-gas tankless heater with a listed output of 7.0 GPM at a 35°F rise. Its 160,000 BTU-per-hour input and non-condensing design place it below the higher-capacity Rheem RTGH and Rinnai models in this group. Rheem says it can handle two to three simultaneous showers, depending on conditions.
The wall-mounted design can free up floor space compared with a tank-style heater. It also has a digital LED control panel with temperature adjustments in 1°F increments, plus built-in freeze and flame-failure protection. Rheem lists LeakGuard leak detection and prevention as another feature.
Its 0.82 UEF is lower than the listed figures for the two condensing models in this comparison. That may make it a more straightforward option for a home with moderate demand, but it is not the choice to make if you regularly run many hot-water fixtures at once. Confirm that your home can accommodate its direct-vent installation and natural-gas requirements.
Pros:
- Listed output of 7.0 GPM at a 35°F rise
- Space-saving wall-mounted design
- Leak detection and prevention feature
- Digital temperature adjustment in 1°F increments
Cons:
- Listed capacity is lower than the 9.0 and 11.1 GPM models in this comparison
- Natural gas only; it is not listed for propane
Verdict: Consider this Rheem for a smaller or moderate-demand household that wants an indoor natural-gas tankless unit with leak protection, rather than the highest capacity available.
4. Rheem Prestige: Built-In Recirculation for Less Waiting
The Rheem Prestige is an indoor natural-gas tankless model with built-in recirculation and a listed flow rate of 11.0 GPM. Its main distinction is not just capacity: Rheem says the recirculation feature is designed to reduce the wait for hot water, while auto-learn programming tracks usage and adapts to peak hot-water needs.
The product description also lists water- and gas-leak detection that can shut down the unit and provide an error code. Its compact design may be useful when replacing a tank heater and reclaiming floor space. If reducing the wait at taps is a priority, its built-in recirculation sets it apart from the other picks here.
The supplied product information does not list a UEF, BTU input, or detailed venting specifications for this model. That makes it harder to compare on efficiency or verify installation needs from the listed details alone. Check the product documentation and have an installer confirm compatibility, including whether the recirculation setup fits your plumbing.
Pros:
- Built-in recirculation is designed to reduce hot-water wait time
- Auto-learn programming tracks use and adapts to peak demand
- Listed flow rate of 11.0 GPM
- Water- and gas-leak detection with automatic shutdown
Cons:
- Supplied details do not state its UEF or BTU input
- Confirm venting and recirculation compatibility before purchasing
Verdict: Pick the Prestige if built-in recirculation and usage-based programming matter more to you than having complete efficiency and input specifications in the supplied listing details.
5. Rheem RTG 7.0 GPM Outdoor: Propane-Powered Choice
This Rheem RTG is an outdoor tankless water heater designed for liquid propane. It has a listed output of 7.0 GPM at a 35°F rise and a 160,000 BTU-per-hour input. Because it installs outdoors, it avoids the need for indoor venting, and its metal cabinet is designed for outdoor installation.
Like the indoor RTG model, this is a non-condensing heater with a listed 0.82 UEF. Rheem describes it as suitable for two to three simultaneous showers, but your results will depend on incoming water temperature and how many fixtures you use at the same time. The model also includes digital temperature adjustment, freeze protection, and flame-failure protection.
This unit is a focused choice for homes that use propane and can accommodate outdoor installation. It is not a natural-gas model, and its outdoor placement may not suit every property or climate. Have an installer check the proposed location, fuel connection, and local installation requirements before buying.
Pros:
- Designed for liquid propane
- Outdoor installation eliminates indoor venting
- Listed output of 7.0 GPM at a 35°F rise
- Includes freeze protection and flame-failure protection
Cons:
- Propane only; not a fit for natural-gas-only homes
- Outdoor placement is required
Verdict: Choose this Rheem if your home uses propane and outdoor installation is practical; skip it if you need an indoor or natural-gas unit.
How to Choose a Gas Tankless Water Heater
Know What “Power Vent” Means for Your Project
A power-vent water heater usually refers to a storage-tank model that uses a powered fan to move combustion exhaust through a vent. The products in this comparison are tankless units, and their listed setups include direct venting or outdoor installation. If you specifically need a power-vent tank heater, verify the product type before ordering rather than assuming a tankless model is interchangeable.
Match the Fuel Type
Check whether your home uses natural gas or propane. Most of the models here are natural-gas units, while the outdoor Rheem RTG is listed for liquid propane. The Rinnai RX199iN supports either fuel through its Smart Sense gas control system. A fuel mismatch can rule out a model, so confirm the exact configuration with the manufacturer and installer.
Size for Flow and Incoming Water Temperature
Flow rate is useful for comparing models, but a listed GPM figure does not tell the whole story. The Rheem RTGH and RTG flow figures are stated at a 35°F rise; the Rinnai listing gives a maximum of 11.1 GPM. Colder incoming water requires a greater temperature increase to reach your set point, which can affect how many fixtures the heater can serve at once. List the fixtures you expect to use together and ask a qualified professional to size the unit for your location.
Check Venting and Installation Location
Indoor and outdoor models have different installation needs. The Rheem RTGH and indoor RTG are listed for indoor direct-vent installation, while the propane Rheem RTG is made for outdoor installation. The Rinnai can be installed indoors or outdoors, but outdoor installation requires the RX-OVC vent cap. Confirm clearances, vent components, and local requirements before choosing based on location alone.
Compare Efficiency on the Same Terms
UEF is a useful comparison figure when it is provided, but it is not the only factor in operating cost. The listed values are 0.93 for the Rheem RTGH, 0.98 for the Rinnai RX199iN, and 0.82 for the Rheem RTG models. The supplied information does not give a UEF for the Rheem Prestige, so compare its official product documentation before making an efficiency decision.
Consider Features You Will Actually Use
Temperature controls, leak detection, recirculation, and app connectivity can influence everyday convenience. The Rheem models offer digital temperature adjustment, and some include leak protection. The Prestige adds built-in recirculation and auto-learn programming. The Rinnai has a Quick Flush feature, but its Wi-Fi control module is not included. Focus on features that solve a real need in your home rather than choosing by feature count.
Review Warranty Details and Professional Installation Needs
Warranty coverage varies by model and may depend on registration. For example, the Rinnai listing says labor coverage is five years when the product is registered within 90 days of installation; otherwise, labor coverage defaults to one year. Check the full warranty terms for the model you choose. These are gas appliances, and the product information recommends professional installation for several models, so include qualified installation and setup in your buying plan.
Frequently Asked Questions
Are these power-vent water heaters?
No. The products compared here are gas tankless water heaters. Some are listed as indoor direct-vent units, and others are designed for outdoor installation. A conventional power-vent storage-tank heater is a different product type.
Which model has the highest listed flow rate?
The Rinnai RX199iN has the highest stated maximum in this comparison at up to 11.1 GPM. The Rheem Prestige is listed at 11.0 GPM. Actual output depends on incoming water temperature and household demand.
Which models can use propane?
The Rinnai RX199iN supports natural gas or propane. The Rheem RTG 7.0 GPM outdoor model is listed for liquid propane. The other Rheem models in this comparison are listed for natural gas.
Can I install a tankless water heater myself?
Professional installation is recommended in the supplied information for several models, and the Rinnai listing specifically advises using a technician. Because installation involves gas, venting, and other home-specific requirements, ask a qualified professional to confirm the right setup.
Does a higher GPM rating guarantee several showers at once?
No. A GPM figure is a useful capacity guide, not a guarantee for every home. Incoming water temperature, desired output temperature, and other running fixtures all affect how much hot water the unit can supply at once.
Does the Rinnai include Wi-Fi control?
The product information says a Controlr module is needed for Wi-Fi control and is not included. Check the current product details for compatible control options.
Which model is best if I want hot water to arrive sooner at the tap?
The Rheem Prestige is the only model here specifically described as having built-in recirculation intended to reduce hot-water wait time. Confirm that its recirculation setup is compatible with your plumbing before choosing it.
Final Recommendation
For flexible fuel and installation options, the Rinnai RX199iN stands out on the supplied specifications. For a high-capacity indoor natural-gas option, consider the Rheem RTGH 9.0 GPM. If your priority is built-in recirculation, the Rheem Prestige has a distinct feature set, while the outdoor Rheem RTG is a practical option for a propane home. Since none of these is a conventional power-vent tank heater, confirm the product type and have an installer verify sizing and venting before you buy.
