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You may be considering apus 80000 btu indoor propane alternatives if the APUS unit does not match your specific needs. The APUS model delivers stable temperature control within ±1°F and fits compact indoor spaces with its low-profile design. It supports 2–3 water points at 3.6 GPM, making it suitable for small households or apartments. However, you might need higher flow rates for multiple bathrooms or a different physical size for your installation area. Some users also prefer electric options if propane infrastructure is unavailable.
We selected these 6 alternatives because their specifications overlap with the original APUS heater. This list includes other indoor propane units with varying BTU outputs and flow capacities. You will find options ranging from 3.06 GPM single-shower models to 8.5 GPM high-capacity systems. The selection also covers electric tankless heaters for those with adequate 240V power. Each product here shares the tankless, indoor, and propane or electric attributes of the APUS unit. This ensures you can compare like-for-like specifications to find the best fit for your home.
01 How these models differ from the APUS
Ranein 3.6 GPM Indoor Propane Tankless Heater
The Ranein 3.6 GPM unit matches the APUS flow rate and 80,000 BTU heating capacity for similar household demand. It shares the indoor propane fuel type and compact tankless form factor. The Ranein distinguishes itself with dual-chamber combustion efficiency, which may improve thermal performance during steady use. Its dimensions are slightly smaller at 13.8 inches wide and 21.7 inches high, making it easier to fit in tighter utility closets. You get included ventilation components, which simplifies installation compared to sourcing parts separately. If you want similar performance with potentially better efficiency and easier setup, this is a practical alternative. It sacrifices the APUS LED display but maintains steady temperature control for medium homes.
ThermoMate Propane 3.06 GPM
The ThermoMate 3.06 GPM model reduces flow rate and heating capacity to 75,000 BTU, targeting single-bathroom applications. It is significantly narrower at 15.9 inches wide but taller at 28.1 inches high. This vertical profile suits spaces with limited width but available height. The unit removes the need for high flow, making it ideal for users who only need hot water for one shower at a time. It sacrifices the ability to serve multiple fixtures simultaneously, which the APUS handles well. The metallic silver finish offers a different aesthetic. If your primary goal is saving space in a small bathroom without needing high capacity, this compact option fits better. It lacks the multi-point support of the APUS but delivers stable heat for single-use scenarios.
Rinnai 8.5 GPM Indoor Propane Tankless Water Heater
The Rinnai 8.5 GPM unit drastically increases capacity with 180,000 BTU and nearly double the flow rate of the APUS. It is designed for large homes with multiple bathrooms requiring simultaneous hot water. The unit is heavier at 53.8 pounds and requires 240V power for its smart features, unlike the APUS 120V system. Its dimensions are 14.1 inches wide and 27.3 inches high. You gain the ability to support more fixtures at once, but you sacrifice energy efficiency and simplicity. The Rinnai is a premium choice for high-demand households. If you need to run showers and sinks simultaneously without temperature drops, this high-output model is the superior option. It is overkill for small apartments but essential for larger families.
GASLAND 4 GPM Propane Indoor Heater
The GASLAND 4 GPM model offers slightly higher flow than the APUS at 4 GPM, with a compact design measuring 15.1 inches wide and 9.4 inches high. It is shorter than the APUS, making it suitable for low-ceiling installations. The black finish provides a different visual option. It maintains indoor propane usage and tankless efficiency. You gain a bit more flow capacity for small households while keeping a small footprint. The unit sacrifices some of the APUS advanced temperature stability features, focusing on reliable performance instead. If you need a bit more hot water for a small home and prefer a shorter unit, this is a solid alternative. It fits well in tight spaces where height is a constraint.
Novieex 4.3 GPM Propane Tankless Water Heater
The Novieex 4.3 GPM unit provides higher flow than the APUS with 100,000 BTU heating capacity. It is designed for high-flow indoor multi-bathroom households. The dimensions are 13.8 inches wide and 23.2 inches high, similar to the APUS but slightly narrower. It weighs 19.8 pounds, comparable to the APUS. You gain increased capacity for simultaneous use without a significant size increase. The unit sacrifices some of the APUS advanced safety sensors and LED display in favor of raw output. It is ideal for users who need more hot water for multiple bathrooms. If you prioritize flow rate over precise temperature control features, this model offers a practical upgrade for larger indoor setups.
Thermomate 18kW Electric Tankless Water Heater
The Thermomate 18kW Electric unit switches from propane to electric power, requiring 240V electrical capacity. It is designed for single-shower applications with precise temperature control. The unit is 13.1 inches wide and 17.1 inches high, making it shorter and narrower than the APUS. It eliminates the need for gas venting and propane tanks. You gain easier installation if you have adequate electrical infrastructure. The unit sacrifices the ability to provide hot water for multiple fixtures simultaneously. It is best for users who cannot run gas lines or prefer electric simplicity. If you need a compact, precise solution for a single shower and have 240V power, this electric alternative is a practical choice.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | APUS 80,000 BTU Indoor Propane Tankless Heater Best overall | Small indoor spaces needing stable hot water | |
| 2 | Ranein 3.6 GPM Indoor Propane Tankless Heater Best budget | Medium homes needing steady hot water | |
| 3 | ThermoMate Propane 3.06 GPM Best bathroom | Single bathroom showers with space constraints | |
| 4 | Rinnai 8.5 GPM Indoor Propane Tankless Water Heater Best premium | Large homes needing high flow rates | |
| 5 | GASLAND 4 GPM Propane Indoor Heater Also great | Small households needing stable hot water | |
| 6 | Novieex 4.3 GPM Propane Tankless Water Heater Also great | high-flow indoor multi-bathroom households | |
| 7 | Thermomate 18kW Electric Tankless Water Heater Best shower | single shower applications with 240V power |
APUS 80,000 BTU Indoor Propane Tankless Heater
Best for: Small indoor spaces needing stable hot water
- Fuel Type
- Propane
- Max Flow Rate
- 3.6 GPM
- Heating Capacity
- 80,000 BTU
- Installation Location
- Indoor
- Voltage
- 120 V AC
- Fixture Capacity
- 2–3 Points
The APUS 80,000 BTU propane water heater delivers 3.6 GPM for two to three fixtures. It uses a copper heat exchanger and segmented combustion for stable temperature control between 95 and 149°F. The compact wall-mount design fits tight indoor spaces. It includes anti-freeze protection and multiple safety shut-offs. This unit suits small homes or apartments needing reliable on-demand hot water.
- 80,000 BTU heating capacity supports 3.6 GPM flow
- Stable temperature control within ±1°F of set point
- Oxygen-free copper heat exchanger for efficient heat transfer
- Anti-freeze protection activates near 41°F
- Compact wall-mount form factor saves floor space
- Lower maximum flow rate of 3.6 GPM compared to competitors reaching 4.3 GPM
- Heavier build at 19.2 pounds versus lighter compact units
- Shorter warranty coverage of 2 years compared to industry standards
- You need hot water for two to three fixtures simultaneously
- You have limited indoor space for a wall-mounted unit
- You require stable temperature control for comfort
- You need a flow rate higher than 3.6 GPM
- You require a longer warranty than 2 years
- You are looking for a unit with higher BTU capacity
Verdict: APUS 80K BTU Propane Tankless Heater provides steady hot water for small households with limited space. It fits buyers who prioritize temperature stability and compact installation over high flow rates.
Ranein 3.6 GPM Indoor Propane Tankless Heater
Best for: Medium homes needing steady hot water
- Fuel Type
- Propane Gas
- Max Flow Rate
- 3.6 GPM
- Heating Capacity
- 80,000 BTU
- Installation Location
- Indoor
- Fixture Capacity
- 2-3 water points
- Temperature Range
- 95°F-149°F
The Ranein indoor propane tankless water heater delivers 80,000 BTU and 3.6 GPM. It supports two to three simultaneous water points. The unit features a copper heat exchanger and adjustable temperature settings from 95°F to 149°F. This model includes a vent pipe. It suits households needing reliable on-demand hot water for multiple fixtures.
- 80,000 BTU heating capacity
- 3.6 GPM maximum flow rate
- Dual heating chambers for efficiency
- Oxygen-free copper heat exchanger
- Built-in anti-freeze protection
- 3.6 GPM flow is lower than the 4.3 GPM Novieex model
- 80,000 BTU is less powerful than the 98,500 BTU GASLAND unit
- Heavier at 18 pounds than the 13.8-pound ThermoMate option
- You need hot water for two to three fixtures
- You want a unit with a copper heat exchanger
- You prefer propane for indoor heating
- You require more than 3.6 GPM flow
- You need higher than 80,000 BTU power
- You live above 2,000 feet elevation
Verdict: Ranein 80,000 BTU Propane Heater offers solid dual-chamber efficiency for medium-sized homes. It fits users who prioritize steady temperature control and included ventilation over maximum flow speed.
ThermoMate Propane 3.06 GPM
Best for: Single bathroom showers with space constraints
- Fuel Type
- Propane
- Max Flow Rate
- Up to 3.06 GPM
- Heating Capacity
- 75,000 BTU
- Installation Location
- Indoor
- Voltage
- 120V
- Temperature Range
- 90–140°F
The ThermoMate indoor propane tankless water heater delivers up to 3.06 GPM at 75,000 BTU. It features a 98% thermal efficiency rating and a 3.5-inch LED display for precise control. This compact unit fits well in smaller spaces, offering stable temperatures within ±1°F. It is designed for single-shower use in bathrooms where space and efficiency matter.
- 98% thermal efficiency with 0.81 UEF rating
- Precise temperature control within ±1°F
- Compact 21"H x 13"W x 7"D footprint
- 3.5-inch LED display with diagnostic codes
- Lower 75,000 BTU heating capacity than competitors
- Reduced 3.06 GPM flow rate compared to others
- Maximum 140°F temperature limit restricts high demand
- You need a compact unit for a single bathroom
- You prioritize high thermal efficiency and low energy use
- You want precise digital temperature control via LED display
- You require high flow rates above 4 GPM
- You need heating capacity above 80,000 BTU
- You are installing a whole-house system with multiple outlets
Verdict: ThermoMate 75,000 BTU Propane Heater suits single-bathroom setups where space is tight and efficiency is key. It delivers stable hot water for one shower at a time without the bulk of larger units.
Rinnai 8.5 GPM Indoor Propane Tankless Water Heater
Best for: Large homes needing high flow rates
- Fuel Type
- Propane
- Max Flow Rate
- 8.5 GPM
- Heating Capacity
- 180k BTU
- Installation Location
- Indoor
- Fixture Capacity
- 7 fixtures at once
- Features
- Tankless
This Rinnai unit delivers 180,000 BTU and up to 8.5 GPM for indoor propane heating. It supports seven fixtures running at once. The compact design measures 14.1 by 10.8 by 27.3 inches. You get a 15-year heat exchanger warranty. Professional installation is required. This model suits large households needing high flow rates.
- 180,000 BTU heating capacity
- 8.5 GPM maximum flow rate
- Supports seven fixtures simultaneously
- 15-year heat exchanger warranty
- Heavier at 53.8 pounds than most alternatives
- Requires professional installation
- Larger footprint than compact competitors
- You need hot water for seven fixtures at once
- You want a 15-year heat exchanger warranty
- You have space for a 53.8-pound unit
- You prefer a lighter, easier DIY install
- You only need to run two or fewer fixtures
- You want a smaller, more compact unit
Verdict: Rinnai RE180iP 8.5 GPM Propane Heater handles high demand with 180,000 BTU and 8.5 GPM. It fits large homes with multiple bathrooms needing simultaneous hot water.
GASLAND 4 GPM Propane Indoor Heater
Best for: Small households needing stable hot water
- Fuel Type
- Propane
- Max Flow Rate
- 4 GPM
- Heating Capacity
- 98,500 BTU
- Installation Location
- Indoor
- Fixture Capacity
- Two showers and a kitchen faucet
- Features
- Tankless
The GASLAND CG360LPN3 delivers 98,500 BTU of heating power with a maximum flow rate of 4 GPM. Its compact dimensions of 15.1 inches wide and 9.4 inches high save significant space compared to traditional tanks. This indoor propane unit maintains temperature stability within ±0.5°F. It suits households needing steady hot water for multiple fixtures in tight spaces like apartments or utility closets.
- 98,500 BTU heating capacity for strong performance
- 4 GPM max flow rate supports two showers and a kitchen faucet
- ±0.5°F precision temperature control ensures consistent water heat
- Compact footprint measures 15.1 inches wide and 9.4 inches high
- Lower flow rate of 4 GPM compared to the Rinnai RE180iP at 8.5 GPM
- Lower heating capacity of 98,500 BTU compared to the Novieex at 100,000 BTU
- Indoor installation only, excluding outdoor use cases
- You need a compact unit for tight spaces like apartments
- You want precise temperature stability within ±0.5°F
- You require steady hot water for two showers and a kitchen faucet
- You need higher flow rates than 4 GPM
- You require outdoor installation options
- You need heating power above 98,500 BTU
Verdict: GASLAND 4 GPM Propane Indoor Heater offers precise temperature control and a compact design for small homes. It fits buyers who prioritize stability and space savings over maximum flow capacity.
Novieex 4.3 GPM Propane Tankless Water Heater
Best for: high-flow indoor multi-bathroom households
- Fuel Type
- Propane Gas
- Max Flow Rate
- Up to 4.3 GPM
- Heating Capacity
- 100,000 BTU
- Installation Location
- Indoor
- Voltage
- 110V-120V
- Fixture Capacity
- 2-4 points of use
This Novieex unit delivers 100,000 BTU of heating power for indoor use. It provides up to 4.3 GPM of hot water. The digital thermostat adjusts temperatures between 95°F and 149°F. It supports two to four points of use. The compact design saves space in utility areas. You get reliable on-demand hot water for showers and sinks.
- 100,000 BTU heating capacity for strong performance
- Up to 4.3 GPM flow rate for multiple fixtures
- Digital thermostat with ±1°F precision control
- Wall-mounted design saves over 50% of space
- 19.8 pounds weight is heavier than lighter competitors
- 13.8 inch width is bulkier than compact alternatives
- Recommended for use below 2000 feet altitude only
- You need high flow rates for multiple bathrooms
- You want precise digital temperature control
- You have indoor space for wall mounting
- You live above 2000 feet altitude
- You prefer smaller footprint units
- You need outdoor installation options
Verdict: Novieex 100k BTU Propane Tankless Heater suits households needing high capacity hot water for multiple simultaneous uses. It fits well in indoor spaces where wall mounting is possible and altitude is under 2000 feet.
Thermomate 18kW Electric Tankless Water Heater
Best for: single shower applications with 240V power
- Fuel Type
- Electric
- Max Flow Rate
- Up to 4.4GMP
- Heating Capacity
- 18kW
- Installation Location
- Indoor
- Voltage
- 240 Volt
- Temperature Range
- 80°F to 140°F
This is an electric tankless water heater designed for indoor use. It delivers up to 4.4 GPM with 18kW of heating power. The unit operates on 240V and requires two 40A breakers. You get a digital display with 1-degree adjustments from 80°F to 140°F. Its compact wall-mount design saves floor space. It suits single shower applications where high flow is not the priority.
- 18kW heating capacity for instant hot water
- Digital display allows 1-degree temperature adjustments
- Compact wall-mount design saves space
- ETL certified for safety protection
- Lower flow rate of 4.4 GPM compared to 8.5 GPM or 4.3 GPM alternatives
- Requires 240V power and two 40A breakers
- Heavier and bulkier than smaller 8kW or 11kW models
- You need a dedicated unit for a single shower
- You have existing 240V electrical infrastructure
- You want precise temperature control in 1-degree increments
- You require propane fuel for off-grid use
- You need high flow for multiple simultaneous fixtures
- You lack the space for a 17-inch tall unit
Verdict: Thermomate 18kW Electric Tankless Heater is a solid choice for users prioritizing precise temperature control and compact installation. It fits best in homes with adequate 240V electrical capacity for single-shower use.
02 Specifications side by side
| Spec | APUS 80,000 BTU Indoor Propane Tankless Heater | Ranein 3.6 GPM Indoor Propane Tankless Heater | ThermoMate Propane 3.06 GPM | Rinnai 8.5 GPM Indoor Propane Tankless Water Heater | GASLAND 4 GPM Propane Indoor Heater | Novieex 4.3 GPM Propane Tankless Water Heater | Thermomate 18kW Electric Tankless Water Heater |
|---|---|---|---|---|---|---|---|
| Fuel Type | Propane | Propane Gas | Propane | Propane | Propane | Propane Gas | Electric |
| Max Flow Rate | 3.6 GPM | 3.6 GPM | Up to 3.06 GPM | 8.5 GPM | 4 GPM | Up to 4.3 GPM | Up to 4.4GMP |
| Heating Capacity | 80,000 BTU | 80,000 BTU | 75,000 BTU | 180k BTU | 98,500 BTU | 100,000 BTU | 18kW |
| Installation Location | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor | Indoor |
| Voltage | 120 V AC | – | 120V | – | – | 110V-120V | 240 Volt |
| Fixture Capacity | 2–3 Points | 2-3 water points | – | 7 fixtures at once | Two showers and a kitchen faucet | 2-4 points of use | – |
| Temperature Range | 95–149°F | 95°F-149°F | 90–140°F | – | – | 95°F to 149°F | 80°F to 140°F |
| Features | Tankless | Tankless | Tankless | Tankless | Tankless | Tankless | Tankless |
| Application | – | – | Bathroom | – | – | – | Shower |
| Form Factor | Compact | Compact | – | Compact | Compact | – | – |
| Wattage | – | – | – | – | – | – | 18 kW |
| Intended Use | – | Home | – | – | – | – | – |
| Dimensions | 19.3 × 19.3 × 27.6 inches | 13.8 × 13.8 × 21.7 inches | 28.1 × 15.9 × 9.84 inches | 10.8 × 14.1 × 27.3 inches | 15.1 × 15.1 × 9.4 inches | 13.8 × 13.8 × 23.2 inches | 13.1 × 13.1 × 17.1 inches |
| Weight | 19.2 pounds | 18 pounds | – | 53.8 pounds | – | 19.8 pounds | – |
| Color | Space Gray | Gray-LPG | Metallic Silver | Silver | Black | Gray | Gray |
| Model | AP-AWH-Q10LPG | RH8K-LPG-FC-RATING | CZ264LP | REU-VE2432FFD-US-P | CG360LPN3 | RS-16 | ET180 |
| Size | – | 3.6 GPM Indoor | – | 8.5 GPM | 4 GPM LP | – | 240V/18kW |
03 Frequently asked questions
Which indoor propane tankless heater offers the highest flow rate?
The Rinnai RE180iP provides the highest flow rate at 8.5 GPM. It delivers 180,000 BTU of heating power for large homes with multiple bathrooms. This unit handles simultaneous hot water demand better than smaller models. Its compact form factor allows for indoor installation despite its higher capacity.
What is the smallest propane heater by footprint?
The Ranein 3.6 GPM model has a compact footprint measuring 13.8 inches in width and length. It stands 21.7 inches tall and weighs 18 pounds. This size fits well in medium-sized homes where space is limited. It maintains steady temperature control while occupying minimal wall area.
Can I use these heaters in a bathroom?
Yes, the ThermoMate Propane 3.06 GPM unit is specifically designed for bathroom applications. It fits single-bathroom setups with tight space constraints. The unit delivers stable hot water for one shower at a time. Its metallic silver finish and compact dimensions suit residential bathroom installations.
Which propane heater is best for high-flow needs?
The Novieex 4.3 GPM Propane Tankless Water Heater suits households needing high capacity. It provides 100,000 BTU for multiple simultaneous uses. This model fits indoor spaces where wall mounting is possible. It performs best at altitudes under 2,000 feet for optimal efficiency.
Is there a propane option with precise temperature control?
The GASLAND 4 GPM Propane Indoor Heater offers precise temperature control. It features a compact design suitable for small homes. This model prioritizes stability over maximum flow capacity. Its black finish and 15.1-inch square footprint make it a practical choice for space-conscious buyers.
What is the lightest propane tankless heater on the list?
The Ranein 3.6 GPM unit weighs the least at 18 pounds. Its compact dimensions are 13.8 inches wide and 21.7 inches tall. This lightweight design simplifies indoor installation. It provides steady hot water for medium homes without requiring heavy structural support.
Which heater is best for single shower applications?
The ThermoMate 18kW Electric Tankless Heater is ideal for single shower use. It requires 240V electrical capacity for operation. This unit offers precise temperature control in a compact 13.1-inch square form. It fits homes with adequate electrical infrastructure for efficient single-point heating.
