6 Best Alternatives to the Forimo 4.74 GPM 18L Indoor (2026)
As an Amazon Associate we earn from qualifying purchases. Links on this page are affiliate links.
You might be looking for forimo 4 74 gpm 18l indoor alternatives to find a unit that better fits your specific home requirements. The Forimo 18L model delivers a steady 4.74 GPM flow rate with an 81,888 BTU output, making it strong for simultaneous use. Its copper heat exchanger and low 3.6 PSI water pressure requirement are practical features for many indoor setups. However, you may need a different size, a lower flow rate, or a more efficient condensing design. Some buyers prefer brands with flexible venting options or models that suit smaller spaces better than the Forimo's footprint.
We selected these options because their published specifications overlap with the original product’s core capabilities. This list includes other natural gas indoor heaters with varying flow rates and physical dimensions. You will find units with 4.21 GPM or 3.18 GPM outputs, which may suit moderate demand better. We also included condensing models for higher efficiency. Each alternative here shares the indoor installation and natural gas fuel type, ensuring they are viable replacements. Review the specs to see which dimensions and flow rates match your household’s hot water needs.
Our top pick: Forimo 4.74 GPM 18L Indoor Natural Gas Tankless Heater.
How these alternatives differ
Forimo 4.74 GPM Indoor Natural Gas Water Heater
This Forimo model shares the 4.74 GPM flow rate and indoor natural gas design of the original. The main difference is its slightly taller height at 22 inches compared to the 21.7 inches of the reference unit. It uses a different model number, HW-FM-18-LNG, but maintains the same black finish and digital display features. You get the same steady temperature control and efficient copper heating core. This unit is a direct alternative if your installation space requires that specific vertical dimension. It serves the same high-demand households with multiple hot water points. The footprint remains identical at 13.8 inches wide and deep. Choose this if the height variation fits your venting or clearance needs better than the standard version.
Forimo 4.74 GPM Natural Gas Tankless Water Heater
This premium Forimo option also delivers 4.74 GPM with an 18L capacity for indoor natural gas use. It matches the original in flow rate and digital display functionality. The primary distinction is the model designation, CT1414-HWRSQ, which may indicate internal component variations. The physical dimensions are identical to the reference unit, measuring 21.7 inches high and 13.8 inches wide. It offers the same robust output for busy households. You receive the same steady performance and efficient heating technology. This alternative is suitable if you prefer the specific build associated with this model number. It provides the same simultaneous hot water capability for bathroom and kitchen use. The design remains compact and corrosion-resistant with stainless steel construction.
Forimo 4.21 GPM Natural Gas Indoor Heater
This Forimo unit steps down to a 4.21 GPM flow rate, reducing capacity from the original 4.74 GPM. It is designed for 16L usage rather than 18L, making it better for moderate hot water demands. The physical size changes significantly, standing 25.4 inches tall and 14.4 inches wide. It retains the indoor natural gas fuel type and digital display for precise temperature control. You sacrifice some simultaneous flow capacity for a potentially more compact width in certain directions. This model suits buyers who prioritize steady temperature stability over maximum flow speed. The black finish and digital interface remain consistent with the brand. Choose this if your household usage does not require the higher 4.74 GPM output. It offers solid performance for smaller families or limited simultaneous use.
Forimo 4.21 GPM Natural Gas Tankless Water Heater
Similar to the previous budget option, this Forimo heater provides 4.21 GPM for indoor natural gas needs. It shares the 16L capacity and digital display features. The dimensions differ notably, with a height of 25.4 inches and a width of 14.4 inches. It weighs 23 pounds, providing a stable build for indoor installation. You get the same reliable temperature control and efficient combustion technology. The flow rate is lower than the original 4.74 GPM, which may affect multiple simultaneous fixtures. This unit is practical for homes where space and gas availability align with its specific limits. The black color and digital interface match the original aesthetic. Select this if you need moderate hot water demand handling. It offers a durable stainless steel construction for prolonged service life.
EZ Tankless Ultra HE Natural Gas Water Heater
The EZ Tankless Ultra HE introduces condensing technology for higher efficiency compared to the standard Forimo units. It delivers a lower flow rate of 3.4 GPM, which limits simultaneous high-demand use. The unit is white, contrasting with the black finish of the Forimo models. It measures 27 inches long, 14.5 inches wide, and 6.5 inches high, offering a different profile. The digital display provides precise temperature control for indoor natural gas use. You gain efficiency through condensing tech and flexible venting options. However, the reduced flow rate makes it less suitable for whole-home high-demand scenarios. This alternative fits users prioritizing energy efficiency over maximum flow volume. The compact height allows for different installation configurations. Choose this for efficient whole-home heating with flexible venting requirements.
Camplux 3.18 GPM Indoor Natural Gas Heater
This Camplux unit offers a 3.18 GPM flow rate, which is significantly lower than the original 4.74 GPM. It is designed for smaller households needing precise digital temperature control. The indoor natural gas heater features a black finish and digital display. It measures 22.8 inches high and 14.3 inches wide, providing a compact profile. The 0.5-inch NPT size specification indicates standard fitting compatibility. You sacrifice flow volume for a unit optimized for smaller spaces and lower demand. The precise digital control ensures steady temperature output for single or dual fixtures. This alternative is ideal for users who do not require high simultaneous flow rates. The compact design fits easily into various indoor installations. Select this if you prioritize precise control and compact placement over maximum hot water volume.
Quick picks
Our 7 picks
Forimo 4.74 GPM 18L Indoor Natural Gas Tankless Heater
Best for: Indoor natural gas homes with low water pressure
- Fuel Type
- Natural Gas (LNG)
- Flow Rate
- 4.74 GPM
- BTU
- 81,888 BTU/hour
- Installation Location
- Indoor
- Temperature Control
- Fahrenheit digital display
- Dimensions
- 21.7 x 13.8 x 13.8 inches
View on Amazon: Forimo 4.74 GPM 18L Indoor Natural Gas Tankless Heater Affiliate link
This Forimo unit delivers 4.74 GPM of hot water using natural gas. It features an 81,888 BTU/hour heat exchanger and a copper water tank for efficient heating. The digital display allows temperature adjustments between 38℃ and 75℃. It requires only 3.6 PSI water pressure and includes a 2.4-inch vent pipe. This model suits indoor installations in homes or small cabins needing instant hot water for multiple fixtures.
Pros
- 4.74 GPM flow rate for simultaneous use
- 81,888 BTU/hour maximum power output
- Built-in oxygen-free copper water tank
- LED digital display for temperature control
- Low 3.6 PSI water pressure requirement
Cons
- Limited to natural gas fuel type
- Indoor installation only
- Includes only a 2.4-inch vent pipe
Good fit if
- You need high flow for two to three fixtures
- You have low water pressure (3.6 PSI)
- You are installing indoors with gas access
Skip if
- You require propane compatibility
- You need outdoor installation capability
- You want a larger 16L or 18L alternative with different specs
Verdict: Forimo 18L Natural Gas Indoor Tankless provides steady 4.74 GPM output with efficient copper heating. It fits indoor spaces where natural gas is available and low water pressure exists.
Forimo 4.74 GPM Indoor Natural Gas Water Heater
Best for: High-demand indoor natural gas households
- Fuel Type
- Natural Gas
- Flow Rate
- 4.74 GPM
- BTU
- 123,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- Fahrenheit digital display
- Dimensions
- 22 x 13.8 x 13.8 inches
View on Amazon: Forimo 4.74 GPM Indoor Natural Gas Water Heater Affiliate link
This Forimo indoor unit delivers 4.74 gallons per minute using natural gas. It features a 123,000 BTU output and a stainless steel heat exchanger with an oxygen-free copper water tank. The digital display lets you set precise temperatures. It requires only 0.2 MPa of water pressure. This model suits homes needing steady hot water for two or three fixtures at once.
Pros
- 4.74 GPM flow rate for simultaneous use
- 123,000 BTU/hr heating capacity
- Digital display for temperature control
- Low 0.2 MPa minimum water pressure requirement
Cons
- Indoor installation only
- Requires dedicated exhaust vent
- Limited to natural gas fuel type
Good fit if
- You need high flow for multiple bathrooms
- You have low incoming water pressure
- You want precise temperature settings
Skip if
- You live in an area without natural gas
- You need outdoor installation options
- You require propane fuel compatibility
Verdict: Forimo 4.74 GPM 18L Natural Gas Heater provides strong performance for households with multiple hot water demands. It is a solid choice for indoor setups where natural gas is available and low water pressure is a concern.
Forimo 4.74 GPM Natural Gas Tankless Water Heater
Best for: High-flow indoor natural gas needs
- Fuel Type
- Natural Gas (LNG)
- Flow Rate
- 4.74 GPM
- BTU
- 81,888 BTU/hour
- Installation Location
- Indoor
- Temperature Control
- Fahrenheit digital display
- Dimensions
- 21.7 x 13.8 x 13.8 inches
View on Amazon: Forimo 4.74 GPM Natural Gas Tankless Water Heater Affiliate link
This Forimo unit delivers 4.74 GPM at 81,888 BTU/hour for indoor use. It features an oxygen-free copper heat exchanger and stainless steel construction. The digital display allows temperature adjustments between 38℃ and 75℃. It requires only 3.6 PSI water pressure and includes a 2.4-inch vent pipe. This model suits homes needing steady hot water for two to three simultaneous points.
Pros
- High flow rate of 4.74 GPM
- 81,888 BTU/hour power output
- Oxygen-free copper water tank
- Digital LED temperature display
- Low 3.6 PSI water pressure requirement
Cons
- Indoor installation only
- Requires proper ventilation setup
- Limited to Natural Gas (LNG) fuel
Good fit if
- You need high flow for multiple fixtures
- You have existing natural gas lines
- You want precise digital temperature control
Skip if
- You require outdoor installation
- You use propane or oil fuel
- You need instant hot water technology
Verdict: Forimo 18L Natural Gas Indoor Heater provides robust 4.74 GPM output for busy households. It fits users who prioritize steady flow and digital control over instant heating features.
Forimo 4.21 GPM Natural Gas Indoor Heater
Best for: Moderate hot water demand with precise control
- Fuel Type
- Natural Gas
- Flow Rate
- 4.21 GPM
- BTU
- 68,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- 86°F-167°F
- Dimensions
- 25.4 x 14.4 x 14.4 inches
View on Amazon: Forimo 4.21 GPM Natural Gas Indoor Heater Affiliate link
This Forimo unit delivers 4.21 gallons per minute at 68,000 BTU/hr. It features a digital display for precise temperature control between 86°F and 167°F. The stainless steel body with a copper heat exchanger resists corrosion. It requires only 3.6 PSI water pressure. This model suits homes needing steady hot water for two to three fixtures simultaneously.
Pros
- 4.21 GPM flow rate for multiple fixtures
- Digital display with 86°F-167°F range
- Stainless steel and copper construction
- Low 3.6 PSI water pressure requirement
Cons
- Lower 4.21 GPM flow rate than 4.74 GPM competitors
- Smaller 16L capacity compared to 18L models
- Heavier build due to copper heat exchanger
Good fit if
- You need reliable hot water for two to three points
- You prefer precise digital temperature control
- You have low water pressure (3.6 PSI)
Skip if
- You require the maximum 4.74 GPM flow rate
- You need an 18L capacity for high demand
- You want a lighter unit for easier mounting
Verdict: Forimo 4.21 GPM 16L Indoor Natural Gas offers solid performance for moderate hot water needs. It fits buyers who prioritize steady temperature control and durability over maximum flow speed.
Forimo 4.21 GPM Natural Gas Tankless Water Heater
Best for: Indoor homes needing moderate natural gas hot water
- Fuel Type
- Natural Gas
- Flow Rate
- 4.21 GPM
- BTU
- 68,000 BTU/hr
- Installation Location
- Indoor
- Temperature Control
- 86°F-167°F
- Dimensions
- 14.4"W x 4.72"H x 25.4"L
View on Amazon: Forimo 4.21 GPM Natural Gas Tankless Water Heater Affiliate link
This Forimo unit delivers 4.21 GPM at 68,000 BTU/hr for indoor natural gas use. It features a digital display with temperature control from 86°F to 167°F. The stainless steel and copper construction aims for durability. It fits 14.4 inches wide and 25.4 inches long. You get steady temperature control with safety protections. It suits homes needing reliable indoor hot water for two to three points.
Pros
- 68,000 BTU/hr maximum power output
- 4.21 GPM flow rate for simultaneous use
- Digital display with 86°F-167°F range
- Stainless steel and oxygen-free copper construction
Cons
- Lower flow rate than the 4.74 GPM leader
- Smaller 16L capacity compared to 18L models
- Limited to natural gas fuel type only
Good fit if
- You need a compact indoor unit for smaller homes
- You prefer digital temperature control precision
- You have natural gas available for installation
Skip if
- You require higher than 4.21 GPM flow
- You need propane compatibility instead of natural gas
- You want the maximum 4.74 GPM capacity
Verdict: Forimo 4.21 GPM 16L Indoor Natural Gas Heater offers solid performance for households with moderate hot water demands. It is a practical pick for indoor installations where space and gas availability align with its specific capacity limits.
EZ Tankless Ultra HE Natural Gas Water Heater
Best for: Efficient whole-home heating with flexible venting
- Fuel Type
- Natural Gas
- Flow Rate
- 3.4 GPM
- Installation Location
- Indoor
- Dimensions
- 27 x 14.5 x 6.5 inches
- Use
- Whole House
- Venting Type
- Condensing
View on Amazon: EZ Tankless Ultra HE Natural Gas Water Heater Affiliate link
The EZ Ultra HE is a natural gas indoor tankless water heater using condensing technology. It recycles exhaust heat to preheat incoming water, boosting efficiency. It offers a flow rate of 3.4 GPM at a 45°F rise. The unit includes a digital display and supports horizontal or vertical venting with standard PVC pipe. This model suits whole-home use where efficiency and compact venting options are priorities.
Pros
- Condensing technology for higher efficiency
- Digital display for easy control
- Flexible horizontal or vertical venting
- Includes back-draft prevention device
Cons
- Lower flow rate of 3.4 GPM
- Larger dimensions than 4.74 GPM models
- No remote control mentioned
Good fit if
- You need high energy efficiency
- You require flexible venting options
- You prefer a digital interface
Skip if
- You need 4.74 GPM flow
- You want a compact 16L unit
- You require instant hot water at higher flow
Verdict: EZ Ultra HE Condensing Gas Heater delivers efficiency through condensing tech and flexible venting, but its 3.4 GPM flow limits it for high-demand households.
Camplux 3.18 GPM Indoor Natural Gas Heater
Best for: smaller households needing precise digital control
- Fuel Type
- Natural Gas
- Flow Rate
- 3.18 GPM
- BTU
- 82,000 BTU
- Installation Location
- Indoor
- Dimensions
- 22.8 x 14.3 x 14.3 inches
- Use
- Whole House
View on Amazon: Camplux 3.18 GPM Indoor Natural Gas Heater Affiliate link
This Camplux unit delivers 3.18 GPM of hot water using 82,000 BTU of natural gas power. It features an oxygen-free copper heat exchanger for efficient heating and an LED digital display for temperature control. The compact 22.8-inch height fits indoor spaces. It supports simultaneous use at two to three points. This model suits smaller households or single-bathroom setups needing reliable indoor gas heating.
Pros
- 3.18 GPM flow rate for whole-house use
- 82,000 BTU heating capacity
- Oxygen-free copper heat exchanger
- LED digital display with °F/°C switch
- Includes exhaust pipe for installation
Cons
- Lower 3.18 GPM flow rate compared to 4.74 GPM competitors
- Indoor installation only
- No remote control listed
Good fit if
- You need a compact indoor gas heater
- You prefer a digital temperature display
- You have a smaller household with lower simultaneous demand
Skip if
- You require a flow rate above 4 GPM
- You need outdoor installation capability
- You want a higher capacity 16L or 18L unit
Verdict: Camplux 3.18 GPM Natural Gas Indoor is a solid choice for smaller homes that prioritize precise digital temperature control and compact indoor placement over maximum flow volume.
Specifications side by side
| Spec | Forimo 4.74 GPM 18L Indoor Natural Gas Tankless Heater | Forimo 4.74 GPM Indoor Natural Gas Water Heater | Forimo 4.74 GPM Natural Gas Tankless Water Heater | Forimo 4.21 GPM Natural Gas Indoor Heater | Forimo 4.21 GPM Natural Gas Tankless Water Heater | EZ Tankless Ultra HE Natural Gas Water Heater | Camplux 3.18 GPM Indoor Natural Gas Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Natural Gas (LNG) | Natural Gas | Natural Gas (LNG) | Natural Gas | Natural Gas | Natural Gas | Natural Gas |
| Flow Rate | 4.74 GPM | 4.74 GPM | 4.74 GPM | 4.21 GPM | 4.21 GPM | 3.4 GPM | 3.18 GPM |
| BTU | 81,888 BTU/hour | 123,000 BTU/hr | 81,888 BTU/hour | 68,000 BTU/hr | 68,000 BTU/hr | not stated | 82,000 BTU |
| Installation Location | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor |
| Temperature Control | Fahrenheit digital display | Fahrenheit digital display | Fahrenheit digital display | 86°F-167°F | 86°F-167°F | not stated | not stated |
| Dimensions | 21.7 x 13.8 x 13.8 inches | 22 x 13.8 x 13.8 inches | 21.7 x 13.8 x 13.8 inches | 25.4 x 14.4 x 14.4 inches | 14.4"W x 4.72"H x 25.4"L | 27 x 14.5 x 6.5 inches | 22.8 x 14.3 x 14.3 inches |
| Use | not stated | not stated | not stated | not stated | not stated | Whole House | Whole House |
| Venting Type | not stated | not stated | not stated | not stated | not stated | Condensing | not stated |
| Features | Digital Display | Digital Display | Digital Display | Digital Display | Digital Display | Digital Display | Digital Display |
| Weight | 23.2 pounds | not stated | not stated | not stated | 23 pounds | not stated | not stated |
| Size | 18L | not stated | 18L | not stated | not stated | not stated | 0.5-inch NPT |
| Color | Black | Black | Black(18L-Natural Gas) | Black | Black | White | Black |
| Model | CT1314-HWRSQ | HW-FM-18-LNG | CT1414-HWRSQ | HWRSQ-16L-LNG-2 | Tankless Water Heater-01 | EZ Ultra HE | CA318BNG |
When you evaluate flow rates, you can review liguvcy 4 gpm 4000 psi alternatives to match your exact system demands.
Frequently asked questions
Which Forimo model is best for low water pressure?
The Forimo 4.74 GPM 18L Indoor Natural Gas Tankless Heater is the best overall choice for homes with low water pressure. It provides a steady 4.74 GPM output using efficient copper heating. This design ensures reliable performance in indoor spaces where natural gas is available and water pressure is low.
What is the difference between the Forimo 18L and 16L models?
The primary difference is the heating capacity and flow rate. The 18L models deliver 4.74 GPM, while the 16L models provide 4.21 GPM. The 18L units are slightly shorter at 21.7 inches tall. The 16L units are taller at 25.4 inches. Both use natural gas and feature digital displays for temperature control.
Does the EZ Tankless Ultra HE have a digital display?
Yes, the EZ Tankless Ultra HE Natural Gas Water Heater includes a digital display. It uses condensing technology for higher efficiency and flexible venting options. However, its flow rate is limited to 3.4 GPM, which may not suit households with very high hot water demands compared to the Forimo 18L options.
Which unit is best for smaller households with precise control needs?
The Camplux 3.18 GPM Indoor Natural Gas Heater is ideal for smaller households. It prioritizes precise digital temperature control over maximum flow volume. This unit is compact and suitable for indoor placement. It fits homes where users value steady temperature accuracy rather than the highest possible gallons per minute output.
Are all listed alternatives indoor natural gas units?
Yes, all listed alternatives are designed for indoor installation and use natural gas as their fuel source. Each unit features a digital display for user control. The Forimo models vary in flow rate from 3.18 to 4.74 GPM. The EZ Tankless unit also supports whole-house use with condensing technology for efficiency.
What are the dimensions of the Forimo 4.21 GPM 16L model?
The Forimo 4.21 GPM 16L Indoor Natural Gas Heater measures 14.4 inches in width and length. Its height is 25.4 inches. One variant weighs 23 pounds. These dimensions make it a substantial unit for indoor spaces. It offers solid performance for moderate hot water demands with precise temperature control via its digital interface.
Which Forimo model is considered the premium option?
The Forimo 4.74 GPM Natural Gas Tankless Water Heater with model number CT1414-HWRSQ is the best premium option. It provides robust 4.74 GPM output for busy households. This 18L unit fits users who prioritize steady flow and digital control. It is designed for indoor natural gas setups requiring high capacity.