Forimo Natural Gas Tankless Water Heater vs Forimo Propane Tankless Water Heater (2026): Key Differences
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When comparing the forimo natural gas tankless water heater vs propane tankless water, you see two indoor units with identical footprints and safety features. Both models use stainless steel and copper heat exchangers. They share the same BTU rating and digital controls. The main difference lies in fuel compatibility and flow rate. You must choose based on your available gas line and hot water needs.
Key differences
| Aspect | Forimo 16L 4.21 GPM Indoor Propane Heater | Forimo 4.74 GPM Natural Gas Tankless Water Heater |
|---|---|---|
| Fuel Type | Propane (LPG) | Natural Gas (LNG) |
| Flow Rate | 4.21 GPM | 4.74 GPM |
| Size Label | 16L | 18L |
| Model Number | CT1312-HWRSQ | CT1414-HWRSQ |
| Installation Location | Indoor | Indoor |
Which one should you choose?
Choose Forimo 16L 4.21 GPM Indoor Propane Heater if
- You have a propane tank and need a steady supply for one bathroom and a kitchen.
- You prefer a slightly more compact unit labeled as 16L for tight indoor spaces.
- Your existing gas line is connected to liquid propane rather than natural gas.
Choose Forimo 4.74 GPM Natural Gas Tankless Water Heater if
- You want the higher flow rate of 4.74 GPM for simultaneous use at multiple fixtures.
- You are connected to a municipal natural gas line and want the matching model.
- You need the unit labeled as 18L for slightly higher capacity performance.
Verdict: Choose the propane model if your home uses propane tanks or you need the 16L size. Pick the natural gas version if you have a gas line connection and want the highest flow rate. Both units offer the same safety features and indoor installation flexibility.
Gas Type and Flow Rate Comparison
Fuel Compatibility
The Forimo 16L 4.21 GPM Indoor Propane Heater requires propane (LPG) exclusively. It is not compatible with natural gas lines. The Forimo 4.74 GPM Natural Gas Tankless Water Heater works only with natural gas (LNG). You must select the correct unit for your home’s fuel source. Using the wrong fuel type will prevent the heater from operating safely. Both units are designed for indoor installation and include necessary venting components for their specific gas types. Always verify your existing gas line type before purchase to ensure proper function and safety compliance for your household.
Hot Water Capacity
Flow rate determines how many fixtures can run simultaneously. The natural gas model delivers 4.74 gallons per minute. This higher output supports two to three water points at once, such as a shower and kitchen sink. The propane model provides 4.21 gallons per minute. This capacity is sufficient for most bathroom and kitchen demands but offers less simultaneous flow. If you frequently use multiple hot water sources, the natural gas unit provides more consistent pressure and volume. The propane unit remains a practical choice for smaller households or single-point usage scenarios.
Power Output
Both heaters share an identical maximum power output of 81,888 BTU per hour. This rating indicates they generate heat at the same intensity level. The difference in flow rates comes from how efficiently each unit converts that thermal energy into hot water for its specific fuel type. Since the BTU rating is the same, neither unit holds an advantage in raw heating power. You can expect similar heating performance relative to the incoming water temperature for both models. This shared specification simplifies the decision if your primary concern is heating speed rather than volume.
Physical Dimensions
Both units measure 21.7 inches in height, 13.8 inches in width, and 13.8 inches in length. They occupy the exact same wall space, making them interchangeable for existing installations. The propane model weighs 22.9 pounds, while the weight for the natural gas model is not listed in the provided data. Since the footprint is identical, you do not need to modify your mounting bracket or venting layout when switching between these two options. The compact design saves over 50% of space compared to traditional tank heaters.
Temperature Control
Each heater features an LED smart digital display for precise temperature management. You can adjust the output temperature between 38°C and 75°C on both models. The interface allows you to set your preferred water heat level easily. Both units include steady temperature control technology to maintain consistent heat during use. Safety protections like flame failure devices and overheating protection are present on both. The digital display ensures you can monitor and tweak settings accurately, regardless of whether you choose the propane or natural gas variant.
Water Pressure Requirements
Both water heaters operate effectively with a minimum water pressure of 3.6 PSI. This low requirement makes them suitable for homes with standard municipal water pressure or well systems. You do not need a booster pump for typical residential setups. The internal components are designed to handle this pressure range safely. This shared specification ensures that both units will perform reliably in most indoor installation environments. It also simplifies troubleshooting if you experience flow issues, as the baseline pressure need is identical for both the propane and natural gas models.
Which Forimo Tankless Heater Fits You
Natural gas line users
If your home is connected to a natural gas line, this model is the only compatible choice. It delivers 4.74 GPM, providing more hot water per minute than the propane version. You get steady temperature control and safety protections like flame failure detection. The stainless steel and copper construction ensures durability for indoor kitchen or bathroom use.
Propane tank users
This unit is designed exclusively for propane (LPG). It outputs 4.21 GPM, which meets the needs of most small homes or cabins. You can adjust the temperature between 38℃ and 75℃ using the LED display. It requires only 3.6 PSI water pressure and includes a vent pipe for easy indoor installation, making it ideal for remote apartments.
High flow demand users
You need maximum hot water volume for simultaneous use. This natural gas model provides 4.74 GPM, exceeding the propane unit's 4.21 GPM. Both share the same 81,888 BTU/hour power output, but the higher flow rate allows you to run more fixtures at once. The compact 21.7-inch height fits standard indoor spaces without needing an expansion tank.
The products compared
Forimo 16L 4.21 GPM Indoor Propane Heater
Best for: small indoor spaces with propane supply
- Fuel Type
- Propane (LPG)
- Flow Rate
- 4.21 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 16L 4.21 GPM Indoor Propane Heater Affiliate link
This Forimo unit is a propane-powered indoor tankless water heater with a 4.21 GPM flow rate and 81,888 BTU output. It features a stainless steel and copper heat exchanger for durability and an LED digital display for temperature control. The compact design fits well in small spaces like cabins or apartments, providing instant hot water for two to three fixtures simultaneously without requiring an expansion tank.
Pros
- High flow rate of 4.21 GPM supports multiple water points
- 81,888 BTU output ensures efficient heating
- LED digital display allows precise temperature adjustment
- Compact dimensions save over 50% space compared to tank models
Cons
- Lower flow rate than the 4.74 GPM natural gas model
- Indoor installation requires proper ventilation and vent pipe
- Requires standard 1/2 NPT fittings for connection
Good fit if
- You need a compact heater for a small cabin or apartment
- You have a propane gas supply available
- You want digital temperature control with an LED display
Skip if
- You require a flow rate higher than 4.21 GPM
- You are looking for an outdoor installation unit
- You do not have access to propane gas
Verdict: Forimo Propane Tankless Water Heater 4.21 GPM is a solid choice for small indoor spaces where propane is available, though its flow rate is lower than the natural gas counterpart.
Forimo 4.74 GPM Natural Gas Tankless Water Heater
Best for: Indoor natural gas homes needing high flow
- 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 gallons per minute using natural gas. It reaches 81,888 BTU/hour for simultaneous use in two to three locations. The digital display lets you set temperatures between 38℃ and 75℃. It requires only 3.6 PSI water pressure. You get an indoor-rated design with stainless steel construction and a copper heat exchanger. It includes a 2.4-inch vent pipe for installation.
Pros
- 4.74 GPM flow rate supports multiple fixtures
- 81,888 BTU/hour output for efficient heating
- Digital display for precise temperature control
- Low 3.6 PSI water pressure requirement
- Includes 2.4-inch horizontal vent pipe
Cons
- Indoor installation only
- Limited to natural gas fuel type
- Heavier and bulkier than 16L propane models
Good fit if
- You need hot water for multiple simultaneous uses
- You have a natural gas supply line
- You require indoor installation in a home or cabin
Skip if
- You need outdoor installation
- You use propane fuel
- You require a remote control
Verdict: Forimo Natural Gas 4.74 GPM Indoor Heater provides steady hot water for busy households with natural gas. It fits users who need high flow rates and precise digital temperature control for indoor plumbing systems.
Specifications side by side
| Spec | Forimo 16L 4.21 GPM Indoor Propane Heater | Forimo 4.74 GPM Natural Gas Tankless Water Heater |
|---|---|---|
| Fuel Type | Propane (LPG) | Natural Gas (LNG) |
| Flow Rate | 4.21 GPM | 4.74 GPM |
| BTU | 81,888 BTU/hour | 81,888 BTU/hour |
| Installation Location | Indoor | Indoor |
| Temperature Control | Fahrenheit digital display | Fahrenheit digital display |
| Dimensions | 21.7 x 13.8 x 13.8 inches | 21.7 x 13.8 x 13.8 inches |
| Features | Digital Display | Digital Display |
| Weight | 22.9 pounds | not stated |
| Size | 16L | 18L |
| Color | Black | Black(18L-Natural Gas) |
| Model | CT1312-HWRSQ | CT1414-HWRSQ |
Frequently asked questions
Can I swap the gas type on these Forimo heaters?
No, you cannot swap the gas type. The Forimo 16L 4.21 GPM Indoor Propane Heater requires propane exclusively. It is not compatible with natural gas lines. Conversely, the Forimo 4.74 GPM Natural Gas Tankless Water Heater works only with natural gas. You must install the correct model for your fuel source.
Which Forimo model has a higher flow rate?
The Forimo 4.74 GPM Natural Gas Tankless Water Heater has the higher flow rate. It delivers 4.74 gallons per minute. The propane version, the Forimo 16L 4.21 GPM Indoor Propane Heater, provides 4.21 GPM. The natural gas model offers more hot water per minute for busy households.
Do both heaters have digital displays?
Yes, both models feature digital displays. The Forimo 16L 4.21 GPM Indoor Propane Heater includes this feature for precise temperature control. The Forimo 4.74 GPM Natural Gas Tankless Water Heater also has a digital display. You get steady hot water with precise digital temperature control on both units.
Are the physical dimensions the same for both units?
Yes, the physical dimensions are identical. Both the Forimo 16L and 18L models measure 13.8 inches in width and length, with a height of 21.7 inches. The propane model weighs 22.9 pounds. The natural gas model shares the same footprint, making installation space requirements consistent for both.
Which model is better for small indoor spaces?
The Forimo 16L 4.21 GPM Indoor Propane Heater is a solid choice for small indoor spaces with propane supply. Its lower flow rate suits smaller demands. The natural gas model is better for indoor natural gas homes needing high flow. Choose based on your available fuel and water usage needs.
Do these heaters require indoor installation?
Yes, both models are designed for indoor installation. The Forimo 16L 4.21 GPM Indoor Propane Heater is listed for indoor use. The Forimo 4.74 GPM Natural Gas Tankless Water Heater is also for indoor natural gas homes. You must install them indoors according to the manufacturer's safety guidelines.