Rheem IKONIC 8.4 GPM Natural Gas Tankless Water Heater Alternatives: 6 Similar Picks Compared
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The Rheem IKONIC 8.4 GPM Natural Gas Tankless Water Heater delivers strong performance for indoor retrofits. This unit provides 157,000 BTUs and a high flow rate, making it suitable for whole-house hot water needs. Its dual heat exchangers aim to save energy by heating water only when you need it. The flexible venting options allow for room air intake and common venting, which helps with installation in various indoor spaces.
You might look for rheem ikonic 8 4 gpm natural gas tankless water heater alternatives if your home has different requirements. Some buyers need a lower flow rate for compact spaces, while others want higher capacity for large families. Others may prefer propane fuel or smart WiFi controls for remote monitoring. We selected these alternatives because their specifications overlap with the original unit. This list compares 6 similar picks based on flow rate, fuel type, and installation constraints to help you find the right fit.
Our top pick: Rheem IKONIC 8.4 GPM Natural Gas Water Heater.
How these alternatives compare
Rinnai RE180iN 6.9 GPM Natural Gas
The Rinnai RE180iN is smaller and lighter than the Rheem IKONIC, measuring 14.1 inches wide versus 17.3 inches. It weighs 54 pounds compared to 77.6 pounds. This compact size suits tight indoor spaces. However, it has a lower flow rate of 5.0 GPM, which may limit simultaneous use in larger homes. It uses non-condensing venting, unlike the IKONIC’s condensing design. You should choose this if you need a smaller footprint and have moderate hot water demands. The IKONIC is better for whole-house efficiency and higher flow needs.
Rheem RTG 9.5 GPM Natural Gas Water Heater
The Rheem RTG 9.5 GPM offers a higher flow rate of 9.5 GPM compared to the IKONIC’s 8.4 GPM. It includes WiFi connectivity for remote monitoring, which the standard IKONIC lacks. This unit is lighter at 46.5 pounds and narrower at 13.5 inches. It uses non-condensing venting. You should pick this if you need extra capacity for large homes and want smart features. The IKONIC is better for energy efficiency with its condensing design and dual heat exchangers. The RTG prioritizes flow and control over maximum thermal efficiency.
Rheem RTGH 8.4 GPM Indoor Natural Gas Heater
The Rheem RTGH 8.4 GPM matches the IKONIC’s 8.4 GPM flow rate but uses non-condensing technology. It is lighter at 59.9 pounds and narrower at 17.7 inches. This model includes WiFi features for remote control. You should choose this if you want smart capabilities without the condensing system. The IKONIC offers superior energy efficiency through its dual heat exchangers. The RTGH is a good alternative if you prefer non-condensing venting or already have WiFi integration in your home. The IKONIC remains the better choice for strict energy savings.
Rheem IKONIC 8.4 GPM Propane
The Rheem IKONIC 8.4 GPM Propane is identical in size and weight to the natural gas model, measuring 17.3 inches wide and weighing 77.6 pounds. It shares the same 8.4 GPM flow rate. The main difference is the fuel type, requiring propane instead of natural gas. You should select this if your home uses propane. It offers the same flexible venting and indoor installation benefits. The natural gas IKONIC is better if you have a natural gas supply. Both models provide the same condensing efficiency and retrofits compatibility for indoor spaces.
A. O. Smith 160K BTU Indoor Natural Gas Water Heater
The A.O. Smith 160K BTU unit is taller at 36.1 inches and wider at 17.8 inches compared to the IKONIC. It is designed for durability with a focus on heat exchanger longevity. This model is suitable for utility spaces where larger dimensions are acceptable. It lacks specific flow rate data in the provided specs. You should pick this if you prioritize long-term efficiency retention and robust construction. The IKONIC is more compact and offers precise flow control. The A.O. Smith is a solid choice for durability-focused installations in spacious areas.
Noritz 6.6 GPM Indoor Natural Gas Tankless Heater
The Noritz 6.6 GPM is significantly lighter at 38 pounds and narrower at 13.8 inches. It has a lower flow rate of 6.6 GPM compared to the IKONIC’s 8.4 GPM. It uses condensing technology with PVC venting, which simplifies installation. You should choose this if you need a compact unit with easy venting options. The IKONIC provides higher flow for whole-house needs. The Noritz is better for smaller households or spaces where weight and size are critical constraints. The IKONIC remains superior for high-demand applications and energy efficiency.
Quick picks
Our 7 picks
Rheem IKONIC 8.4 GPM Natural Gas Water Heater
Best for: Indoor high-efficiency retrofits
- Fuel Type
- Natural Gas
- Flow Rate
- 8.4 GPM
- BTU
- 157,000 BTUs
- Installation Location
- Indoor
- Dimensions
- 28.6 x 17.3 x 13.7 inches
- Weight
- 77.6 pounds
View on Amazon: Rheem IKONIC 8.4 GPM Natural Gas Water Heater Affiliate link
The Rheem IKONIC 8.4 GPM is an indoor natural gas unit rated at 157,000 BTUs. It features super high-efficiency dual heat exchangers to save energy. The compact design measures 28.6 by 17.3 by 13.7 inches. It supports flexible venting and room air intake. This model suits homes needing reliable hot water for multiple simultaneous uses.
Pros
- 8.4 GPM flow rate for whole-house use
- 157,000 BTU input for high efficiency
- Flexible venting and room air intake options
- Compatible with 1/2 inch gas lines
- 15-year limited warranty
Cons
- Indoor installation only
- Heavier at 77.6 pounds
- No recirculation pump included in base model
Good fit if
- You need high efficiency for energy savings
- You require flexible venting options
- You are replacing a standard tank indoors
Skip if
- You need outdoor installation
- You require a propane fuel type
- You want a built-in recirculation pump
Verdict: Rheem IKONIC 8.4 GPM Natural Gas delivers strong performance for indoor retrofits. It fits buyers who prioritize efficiency and flexible venting over outdoor placement or integrated recirculation.
Rinnai RE180iN 6.9 GPM Natural Gas
Best for: Compact indoor spaces with moderate demand
- Fuel Type
- Natural Gas
- Flow Rate
- 8.5 GPM
- BTU
- 180k BTU
- Installation Location
- Indoor
- Dimensions
- 27.3 x 14.1 x 10.8 in
- Venting Type
- Non-Condensing
View on Amazon: Rinnai RE180iN 6.9 GPM Natural Gas Affiliate link
The Rinnai RE180iN is an indoor, non-condensing natural gas tankless water heater. It delivers up to 6.9 GPM, supporting five fixtures simultaneously. Its compact 27.3 by 14.1 by 10.8 inch footprint fits tight spaces. The unit includes an LED screen for error codes and service reminders. You get a 15-year heat exchanger warranty and 5-year parts coverage. This model suits homes needing reliable indoor heating without condensing venting complexity.
Pros
- Delivers 6.9 GPM flow rate for multiple fixtures
- Compact dimensions fit small indoor spaces
- Includes LED screen for diagnostics and reminders
- 15-year limited warranty on heat exchanger
Cons
- Lower flow rate than 8.4 GPM competitors
- WiFi control module sold separately
- Requires professional installation
Good fit if
- You need a compact indoor unit
- You prefer non-condensing natural gas models
- You want a long heat exchanger warranty
Skip if
- You need more than 6.9 GPM
- You want built-in WiFi connectivity
- You require outdoor installation
Verdict: Rinnai RE180iN 6.9 GPM Natural Gas fits homes with tight indoor spaces and moderate hot water needs. It offers strong warranty coverage but lacks the higher flow rates of larger 8.4 GPM units.
Rheem RTG 9.5 GPM Natural Gas Water Heater
Best for: Large homes needing high flow and WiFi
- Fuel Type
- Natural Gas
- Flow Rate
- 9.5 GPM
- BTU
- 199,900 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTG 9.5 GPM Natural Gas Water Heater Affiliate link
This Rheem unit delivers 9.5 GPM at 199,900 BTU/hr for whole-house use. It features a non-condensing design with an 0.82 UEF. You get WiFi control and ±1°F temperature precision. The indoor model measures 24.2 by 13.5 inches. It suits large families needing multiple simultaneous showers. The compact wall-mount design saves floor space.
Pros
- 9.5 GPM flow rate supports 3-4 showers
- 199,900 BTU/hr high output
- WiFi enabled for remote control
- ±1°F digital temperature precision
Cons
- Indoor installation only
- Non-condensing design limits efficiency vs condensing models
- Requires professional installation
Good fit if
- You need high flow for multiple bathrooms
- You want WiFi connectivity
- You have indoor venting space
Skip if
- You need outdoor installation
- You require condensing efficiency
- You prefer DIY setup
Verdict: Rheem RTG 9.5 GPM Natural Gas offers high capacity and smart control for large homes. It fits households prioritizing simultaneous shower use and remote monitoring.
Rheem RTGH 8.4 GPM Indoor Natural Gas Heater
Best for: Large families needing high flow rate efficiency
- Fuel Type
- Natural Gas
- Flow Rate
- 8.4 GPM
- BTU
- 157,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- ±1°F
- Certification
- CSA
View on Amazon: Rheem RTGH 8.4 GPM Indoor Natural Gas Heater Affiliate link
This Rheem unit delivers 8.4 GPM at a 35°F rise, powered by 157,000 BTUs. It features a 0.93 UEF for high efficiency and indoor direct venting. The digital LED control offers ±1°F precision. It includes built-in freeze protection and multi-point safety systems. This model suits large families needing whole-house hot water for three to four simultaneous showers.
Pros
- 8.4 GPM flow rate for whole-house use
- 0.93 Uniform Energy Factor for efficiency
- ±1°F digital LED temperature precision
- Indoor direct vent installation
Cons
- No WiFi connectivity in this 8.4 GPM variant
- Indoor installation only
- 5-year parts warranty is shorter than the heat exchanger warranty
Good fit if
- You need 8.4 GPM for a large family
- You want high efficiency with a 0.93 UEF
- You require precise temperature control within ±1°F
Skip if
- You need outdoor installation capability
- You require WiFi smart home integration
- You want a longer 5-year parts warranty
Verdict: Rheem IKONIC 8.4 GPM Natural Gas offers high efficiency and precise control for large households. It fits buyers who prioritize steady hot water flow and energy savings over smart features.
Rheem IKONIC 8.4 GPM Propane
Best for: indoor propane retrofits
- Fuel Type
- Liquid Propane
- Flow Rate
- 8.4 GPM
- BTU
- 157,000 BTU/hr
- Installation Location
- Indoor
- Dimensions
- 28.6 x 17.3 x 13.7 inches
- Weight
- 77.6 pounds
View on Amazon: Rheem IKONIC 8.4 GPM Propane Affiliate link
This unit delivers 8.4 GPM of hot water using liquid propane fuel. It features a 157,000 BTU/hr input and weighs 77.6 pounds. The compact design fits indoor spaces with flexible venting options. It supports retrofits with ½” gas lines. This heater suits homes seeking high-efficiency propane performance for multiple simultaneous uses.
Pros
- 8.4 GPM flow rate for whole-house use
- 157,000 BTU/hr input power
- Compatible with flex venting for easy retrofits
- 15-year limited warranty coverage
Cons
- Indoor installation only
- Requires liquid propane fuel source
- Heavier at 77.6 pounds
Good fit if
- You need a high-output propane water heater
- You are replacing a tank unit indoors
- You want flexible venting options
Skip if
- You require outdoor installation
- You use natural gas instead of propane
- You need recirculation pump support
Verdict: Rheem IKONIC 8.4 GPM Propane is a solid choice for indoor propane retrofits. It fits homes needing reliable whole-house hot water with flexible venting capabilities.
A. O. Smith 160K BTU Indoor Natural Gas Water Heater
Best for: Durability-focused indoor hot water needs
- Fuel Type
- Natural Gas
- BTU
- 160K BTU
- Installation Location
- Indoor
- Dimensions
- 36.1 x 17.8 x 17.8 inches
View on Amazon: A. O. Smith 160K BTU Indoor Natural Gas Water Heater Affiliate link
This A.O. Smith indoor natural gas heater delivers 160,000 BTUs with a 0.94 Uniform Energy Factor. Its commercial-grade copper heat exchanger transfers heat faster than stainless steel options. The X3 Technology helps maintain efficiency over time. It measures 36.1 inches tall and mounts on your wall. This unit suits homes needing high performance and long-term reliability without frequent efficiency drops.
Pros
- 160,000 BTU input for strong hot water output
- 0.94 Uniform Energy Factor for high efficiency
- Primary copper heat exchanger for quick temperature stabilization
- 15-year limited warranty covers scale-related failures
- X3 Technology maintains like-new performance over time
Cons
- Larger footprint at 36.1 inches tall and 17.8 inches wide
- Indoor installation only requires proper venting
- No digital display or remote control mentioned in specs
Good fit if
- You need a high-efficiency unit with a copper heat exchanger
- You want a 15-year warranty for peace of mind
- You have space for a 36-inch tall indoor unit
Skip if
- You need an outdoor installation option
- You prefer a more compact wall-mount design
- You want smart home connectivity features
Verdict: A.O. Smith 240HX3 160K BTU Indoor Unit is a robust choice for homeowners prioritizing heat exchanger durability and long-term efficiency retention. It fits well in utility spaces where its larger dimensions are acceptable.
Noritz 6.6 GPM Indoor Natural Gas Tankless Heater
Best for: Indoor PVC venting efficiency
- Fuel Type
- Natural Gas
- Flow Rate
- 6.6 GPM
- Installation Location
- Indoor
- Venting Type
- Condensing
- Dimensions
- 6.7 × 13.8 × 23.6 inches
- Weight
- 38 pounds
View on Amazon: Noritz 6.6 GPM Indoor Natural Gas Tankless Heater Affiliate link
The Noritz NRC66DVNG is an indoor natural gas tankless water heater with a 6.6 GPM flow rate. It uses condensing technology for high efficiency and low NOx emissions. The unit measures 13.8 inches wide and 23.6 inches high. It includes a remote thermostat and a 6-foot power cord. You can vent it using Schedule 40 PVC pipe. This model suits homes needing efficient indoor heating with flexible venting options.
Pros
- 6.6 GPM flow rate for natural gas
- Condensing design for high efficiency
- Uses standard Schedule 40 PVC venting
- Includes remote thermostat and 6' power cord
Cons
- Lower 6.6 GPM flow rate than 8.4 GPM competitors
- Heavier at 38 pounds
- Indoor installation only
Good fit if
- You need high efficiency in an indoor space
- You want to use PVC venting
- You prefer a compact 13.8-inch wide unit
Skip if
- You require an 8.4 GPM flow rate
- You need outdoor installation capability
- You prefer a lighter unit under 30 pounds
Verdict: Noritz NRC66DVNG 6.6 GPM Condensing Heater fits buyers who prioritize efficiency and easy PVC venting over maximum flow rate. It is a solid choice for indoor spaces where standard venting is preferred.
Specifications side by side
| Spec | Rheem IKONIC 8.4 GPM Natural Gas Water Heater | Rinnai RE180iN 6.9 GPM Natural Gas | Rheem RTG 9.5 GPM Natural Gas Water Heater | Rheem RTGH 8.4 GPM Indoor Natural Gas Heater | Rheem IKONIC 8.4 GPM Propane | A. O. Smith 160K BTU Indoor Natural Gas Water Heater | Noritz 6.6 GPM Indoor Natural Gas Tankless Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas | Natural Gas | Natural Gas | Natural Gas | Liquid Propane | Natural Gas | Natural Gas |
| Flow Rate | 8.4 GPM | 8.5 GPM | 9.5 GPM | 8.4 GPM | 8.4 GPM | not specified | 6.6 GPM |
| BTU | 157,000 BTUs | 180k BTU | 199,900 BTU/hr | 157,000 BTU/hr | 157,000 BTU/hr | 160K BTU | not specified |
| Installation Location | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor |
| Temperature Control | not specified | not specified | ±1°F | ±1°F | not specified | not specified | not specified |
| Certification | not specified | not specified | CSA | CSA | not specified | not specified | not specified |
| Dimensions | 28.6 x 17.3 x 13.7 inches | 27.3 x 14.1 x 10.8 in | 24.2 x 13.5 x 10.3 inches | 23.7 x 17.7 x 9.8 inches | 28.6 x 17.3 x 13.7 inches | 36.1 x 17.8 x 17.8 inches | not specified |
| Venting Type | not specified | Non-Condensing | Non-Condensing | not specified | not specified | not specified | Condensing |
| Features | not specified | not specified | WiFi | WiFi | not specified | not specified | not specified |
| Weight | 77.6 pounds | 54 pounds | 46.5 pounds | 59.9 pounds | 77.6 pounds | not specified | 38 pounds |
| Size | 8.4 GPM | 8.5 GPM | 9.5 GPM (WiFi) | 8.4 GPM (No WiFi) | 8.4 GPM (no Recirc) | not specified | 13.8 inches (W) x 23.6 inches (H) x 10 inches (D) |
| Color | Gray | Silver | Gray | Gray | Gray | White | White |
| Model | RECTGH-S84iN | REU-VE2432FFD-US-N | RTG-95DVELN-3 | RTGH-84DVLN-3 | RECTGH-S84iP | ATI-240HX3-N | NRC661-DV-NG |
For outdoor hookups on your fuel line, compare monument grills 4 1 burner natural gas alternatives by burner output.
Frequently asked questions
Can I use the Rheem IKONIC 8.4 GPM with propane?
Yes, Rheem offers a propane version of this unit. The Rheem IKONIC 8.4 GPM Propane model shares the same physical dimensions as the natural gas version. It measures 17.3 inches wide and 28.6 inches tall. This option allows you to retrofit existing indoor spaces that use propane fuel.
How does the Rinnai RE180iN size compare to the IKONIC?
The Rinnai RE180iN is more compact than the Rheem IKONIC. It measures 14.1 inches wide and weighs only 54 pounds. The IKONIC is wider at 17.3 inches and weighs 77.6 pounds. The Rinnai unit is better for tight indoor spaces where wall clearance is limited.
Which alternative offers the highest flow rate?
The Rheem RTG 9.5 GPM Natural Gas Water Heater provides the highest flow rate in this list. It delivers 9.5 gallons per minute. This exceeds the 8.4 GPM output of the IKONIC. It also includes WiFi connectivity for remote monitoring. This model suits large homes with high demand.
Is there a condensing option for easier venting?
The Noritz 6.6 GPM Indoor Natural Gas Tankless Heater uses condensing technology. This allows for standard PVC venting installation. It is lighter at 38 pounds and smaller in width than the IKONIC. However, its flow rate is lower at 6.6 GPM compared to the IKONIC's 8.4 GPM.
Does the Rheem RTGH 8.4 GPM include WiFi?
No, the Rheem RTGH 8.4 GPM Indoor Natural Gas Heater does not include WiFi. The data specifies this model has no WiFi capability. It shares the 8.4 GPM flow rate and similar dimensions with the IKONIC. It is a good choice if you prefer precise control without smart features.
Which unit is best for durability-focused buyers?
The A.O. Smith 160K BTU Indoor Natural Gas Water Heater is noted for durability. It features a robust heat exchanger designed for long-term efficiency. This unit is larger, measuring 36.1 inches tall and 17.8 inches wide. It fits well in utility spaces where its larger dimensions are acceptable.
Can I install these units outdoors?
No, all listed alternatives are designed for indoor installation. The Rheem IKONIC, Rinnai RE180iN, and other models specify indoor placement. They are not rated for outdoor exposure. You must install them in protected areas like basements or utility closets to ensure proper operation and safety.