10 Best Tankless Water Heaters with 120,000 BTU, Compared
As an Amazon Associate we earn from qualifying purchases. Links on this page are affiliate links.
Finding the best tankless water heaters with 120000 btu requires comparing how each unit handles flow and fuel. We analyzed 10 models based strictly on their published specifications. The APUS 5.43 GPM Propane Tankless Water Heater leads this list because its 5.43 GPM output supports multi-fixture demand in indoor propane homes. Each pick reflects data like BTU ratings, fuel type, and dimensions from the product listings. This guide helps you decide which heater fits your home’s layout and hot water needs.
Quick picks
The best fit for you
- You need the best overall indoor propane unit APUS 5.43 GPM Propane Tankless Water Heater It delivers 5.43 GPM flow with 120,000 BTU propane power for indoor use.
- You want smart WiFi control for your heater MIZUDO 120K BTU WiFi Natural Gas Heater This natural gas model features built-in WiFi for remote management and stable temperatures.
- You require an outdoor propane setup for low elevation NOVIEEX 5.3 GPM Outdoor Propane Tankless Water Heater It provides 5.3 GPM output outdoors without needing indoor venting runs.
- You need a compact indoor natural gas heater Novieex Indoor Natural Gas Tankless Water Heater Its small 16-inch width fits tight spaces while providing 120,000 BTU indoors.
- You want a condensing indoor propane unit with freeze protection VancEpic 5.1 GPM Propane Condensing Water Heater It combines condensing efficiency with integrated freeze protection for indoor propane installations.
Our 10 picks
APUS 5.43 GPM Propane Tankless Water Heater
Best for: indoor multi-fixture propane homes
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Propane
- Flow Rate
- 5.43 GPM
- Installation Location
- Indoor
- Voltage
- 120V AC
- Temperature Control
- 95–149°F, ±1°F
The APUS Propane Tankless Water Heater delivers 120,000 BTU and a max flow rate of 5.43 GPM for indoor setups. It features a 0.66 GPM activation rate, UEF 0.81 rating, and precise temperature adjustments from 95°F to 149°F via an LED touchscreen. Standard 120V AC power runs the controls. If you need propane heating to supply two showers and a sink simultaneously, this compact wall-mounted unit fits your home.
Pros
- 5.43 GPM flow rate supports up to 3 to 4 fixtures
- Low 0.66 GPM minimum activation flow rate
- Temperature adjustment from 95°F to 149°F with ±1°F precision
- Freeze protection system activates near 41°F
- Compact wall-mounted profile measuring 20.55 × 13.27 × 5.91 inches
Cons
- Indoor installation only
- Requires 120V AC electrical connection for smart controls
- Requires manual draining when temperatures drop below 41°F during non-use
Good fit if
- You run propane fuel and require an indoor wall-mounted unit.
- You need up to 5.43 GPM to supply two showers and a sink concurrently.
- You want digital temperature adjustments between 95°F and 149°F.
Skip if
- You use natural gas lines instead of propane.
- You need an outdoor-rated water heater installation.
- You do not have a standard 120V AC outlet near the mounting location.
Verdict: APUS 5.43 GPM Propane Tankless Water Heater delivers 5.43 GPM output and responsive digital temperature control within a compact indoor profile. It effectively handles multi-fixture demand using 120,000 BTU of propane heating power.
MIZUDO 120K BTU WiFi Natural Gas Heater
Best for: Smart control and stable temperature
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Flow Rate
- 5.1 GPM
- Installation Location
- Indoor or Outdoor
- Temperature Control
- ±1°F
- Certification
- CSA
The Mizudo delivers 120,000 BTU and 5.1 GPM for indoor or outdoor use. It features WiFi app control and precise temperature stability within 1°F. The unit includes a copper heat exchanger and CSA certification. This natural gas model suits large households needing reliable hot water for multiple bathrooms simultaneously.
Pros
- WiFi app control for remote management
- Temperature stability within 1°F
- Indoor and outdoor installation flexibility
- CSA certified safety systems
Cons
- Indoor venting requires a specific 3-inch OD pipe
- Outdoor conversion needs a separate accessory kit
- 2-year full warranty is shorter than industry averages
Good fit if
- You want remote temperature adjustments via an app
- You need stable water temperature for multiple fixtures
- You prefer natural gas over propane
Skip if
- You require a propane fuel source
- You need a longer than 2-year full unit warranty
- You want a simpler unit without smart features
Verdict: Mizudo 120,000 BTU Natural Gas Heater offers smart control and precise heating for homes needing high flow rates. It fits users who value remote management and indoor-outdoor versatility.
NOVIEEX 5.3 GPM Outdoor Propane Tankless Water Heater
Best for: outdoor propane setups below 2,000 feet elevation
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Propane
- Flow Rate
- 5.3 GPM
- Installation Location
- Outdoor
- Voltage
- 110V–120V AC
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: NOVIEEX 5.3 GPM Outdoor Propane Tankless Water Heater
This outdoor propane tankless water heater delivers up to 5.3 GPM with a 120,000 BTU burner. Because it mounts on an exterior wall, you avoid installing indoor venting while running standard 3/4-inch NPT lines. It provides digital temperature regulation from 95°F to 149°F. This unit suits you if you need whole-home hot water for two to four fixtures simultaneously without consuming interior utility space.
Pros
- Delivers up to 5.3 GPM to supply two to four fixtures at once
- Outdoor wall mounting eliminates indoor flue and venting runs
- Maintains temperature between 95°F and 149°F within ±1°F
- Includes a digital LED remote control for adjustments
Cons
- Not recommended for locations above 2,000 feet elevation
- Requires manual water draining when temperatures drop below 41°F
- Outdoor placement only, cannot be installed indoors
Good fit if
- You want an outdoor propane setup that bypasses indoor venting requirements.
- You live at an elevation below 2,000 feet.
- You need sufficient flow to serve two to four fixtures at the same time.
Skip if
- You live at an elevation higher than 2,000 feet.
- You need an indoor-mounted water heater.
- You use natural gas rather than liquid propane.
Verdict: Novieex 5.3 GPM Outdoor Propane Tankless Water Heater provides high flow without requiring indoor venting runs. It is a practical exterior solution for low-elevation homes using propane.
Novieex Indoor Natural Gas Tankless Water Heater
Best for: indoor natural gas homes under 2,000 feet
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Flow Rate
- 4.75 GPM
- Installation Location
- Indoor
- Voltage
- 110V–120V AC
- Temperature Control
- 95°F–149°F, ±1°F
View on Amazon: Novieex Indoor Natural Gas Tankless Water Heater
This indoor natural gas tankless water heater delivers up to 4.75 GPM using 120,000 BTU. It features digital temperature control adjustable from 95°F to 149°F with ±1°F precision, an LED touchscreen, and 1/2-inch NPT fittings. It operates on standard 110V to 120V electrical power and includes an exhaust pipe. This unit suits you if you need a compact, wall-mounted natural gas heater for indoor spaces below 2,000 feet elevation.
Pros
- Delivers up to 4.75 GPM at 120,000 BTU
- Adjustable temperature from 95°F to 149°F with ±1°F precision
- Exhaust pipe included in the box
- Digital LED touchscreen interface
Cons
- Recommended only for use below 2,000 feet altitude
- One-year manufacturer warranty
Good fit if
- You have an indoor natural gas supply with 1/2-inch NPT fittings.
- You live at an elevation below 2,000 feet.
- You want precise digital temperature adjustment up to 149°F.
Skip if
- You live at an altitude of 2,000 feet or higher.
- You need an outdoor installation or use propane fuel.
- You require a flow rate higher than 4.75 GPM.
Verdict: Novieex Indoor Natural Gas Tankless Water Heater provides 120,000 BTU output and precise digital temperature regulation for indoor natural gas setups. It is a practical fit if your home sits below 2,000 feet elevation and needs up to 4.75 GPM.
Ranein 5.1 GPM Condensing Natural Gas Water Heater
Best for: mid-sized homes at elevations below 2,000 feet
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Flow Rate
- 5.1 GPM
- Voltage
- 120V
- Temperature Control
- 95°F–149°F, ±1°F
- Certification
- ANSI Z21.10.3
View on Amazon: Ranein 5.1 GPM Condensing Natural Gas Water Heater
This Ranein natural gas tankless water heater delivers up to 5.1 GPM using a 120,000 BTU burner and condensing technology. You can adjust temperatures from 95°F to 149°F through an LED touchscreen with four preset modes. Its compact 22 by 14.2-inch frame includes standard 3/4-inch NPT fittings and venting hardware. It suits you if you need steady hot water across two to three bathrooms in a home under 2,000 feet elevation.
Pros
- Delivers up to 5.1 GPM flow rate with a 120,000 BTU condensing burner
- Includes stainless steel vent pipe and condensate drain line in the box
- Touchscreen controls with 4 operational modes and ±1°F temperature adjustments
- Built-in 114W anti-freeze heating element activates below 42.8°F
Cons
- Not recommended for installations above 2,000 feet elevation
- Requires a dedicated 120V electrical outlet and condensate drainage
Good fit if
- You run natural gas and need to supply two to three bathrooms simultaneously.
- You live below 2,000 feet elevation and want condensing flue heat recovery.
Skip if
- You live at an altitude above 2,000 feet.
- You rely on liquid propane fuel.
Verdict: Ranein 5.1 GPM Condensing Natural Gas Heater pairs efficient flue gas heat recovery with an included venting kit for mid-sized homes. It provides precise digital temperature control for multiple fixtures located below 2,000 feet elevation.
Westinghouse Outdoor Natural Gas Tankless Heater
Best for: outdoor natural gas tankless installations
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Installation Location
- Outdoor
- Dimensions
- 2 × 2 × 2 inches
View on Amazon: Westinghouse Outdoor Natural Gas Tankless Heater
This Westinghouse unit provides tankless water heating designed exclusively for outdoor setup. It runs on natural gas, delivering up to 5.1 GPM flow capacity with a 120,000 BTU thermal rating. The Deep Grey casing mounts externally to save indoor utility space. If you need an exterior natural gas heater that eliminates indoor venting requirements, this configuration serves your household needs.
Pros
- 120,000 BTU maximum heating power
- Flow rate up to 5.1 GPM
- Outdoor installation requires no indoor exhaust venting
- Operates on standard natural gas supply
Cons
- Limited to outdoor installation locations
- Not compatible with liquid propane
Good fit if
- You need an exterior-mounted tankless unit running on natural gas.
- You require a flow rate of up to 5.1 GPM for your fixtures.
Skip if
- You plan to mount your water heater indoors.
- You rely on liquid propane fuel.
Verdict: Westinghouse Outdoor Natural Gas Tankless Heater delivers 120,000 BTU and 5.1 GPM specifically for exterior natural gas setups. It suits homes seeking outdoor wall mounting without indoor venting hardware.
VancEpic 5.1 GPM Propane Condensing Water Heater
Best for: Indoor propane setups in cold climates
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Propane
- Flow Rate
- 5.1 GPM
- Installation Location
- Indoor
- Temperature Control
- 95°F to 149°F
- Dimensions
- 9.25 x 20.2 x 20.2 inches
View on Amazon: VancEpic 5.1 GPM Propane Condensing Water Heater
The VancEpic 5.1 GPM Condensing Propane Water Heater provides on-demand hot water for indoor setups. It runs on liquid propane at 120,000 BTU per hour, delivering up to 5.1 GPM through a stainless steel heat exchanger. The condensing design captures exhaust heat, and an integrated 114W anti-freeze heater protects components in freezing conditions. It fits you if you need indoor propane hot water for apartments or small homes.
Pros
- Condensing stainless steel heat exchanger captures waste heat
- Flow rate up to 5.1 GPM at 120,000 BTU output
- Integrated 114W anti-freeze heating element for sub-zero protection
- Digital LED display monitors temperature, gas flow, and water flow
- Supplied with vent pipe and condensate drain line
Cons
- Designed only for indoor installation
- Requires propane fuel supply rather than natural gas
- Warranty limited to 2 years for heat exchanger and parts
Good fit if
- You need an indoor water heater fueled by liquid propane.
- You want condensing efficiency with a stainless steel heat exchanger.
- You require built-in electric freeze protection for freezing temperatures.
Skip if
- You need a heater compatible with natural gas lines.
- You plan to install your water heater outdoors.
- You demand a flow rate greater than 5.1 GPM for a larger home.
Verdict: VancEpic 5.1 GPM Condensing Propane Water Heater combines 120,000 BTU condensing performance with integrated freeze protection for indoor propane installations. It delivers reliable multi-fixture capacity for apartments and small homes.
Westinghouse Outdoor Propane 5.1 GPM Tankless Heater
Best for: outdoor propane setups running multiple fixtures
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Propane
- Flow Rate
- 5.1 GPM
- Installation Location
- Outdoor
- Voltage
- 120 V AC
- Temperature Control
- 95°F–158°F, ±1°F
View on Amazon: Westinghouse Outdoor Propane 5.1 GPM Tankless Heater
This outdoor propane tankless water heater delivers up to 5.1 GPM with a 120,000 BTU burner and outdoor wall mounting. It features a minimum activation flow of 0.53 GPM at 15 PSI, heating water between 95°F and 158°F with a wired controller. It suits you if you run two to four fixtures simultaneously and prefer an exterior setup that requires a 120V electrical outlet.
Pros
- Delivers up to 5.1 GPM flow rate for 2 to 4 fixtures
- Activates at 0.53 GPM with minimum 15 PSI water pressure
- Includes wired digital controller with 95°F to 158°F range
- Equipped with a 12-speed DC anti-backdraft fan
Cons
- Outdoor wall mounting only
- Requires a 120V AC outdoor electrical connection
- Must be manually drained below 32°F during power outages
Good fit if
- You want an exterior propane water heater for 2 to 4 simultaneous fixtures.
- You have low water pressure down to 15 PSI.
- You have an exterior 120V power supply at the mounting site.
Skip if
- You need an indoor water heater installation.
- You fuel your home with natural gas instead of propane.
- You do not have an outdoor electrical outlet available.
Verdict: Westinghouse Outdoor Propane 5.1 GPM Tankless Heater provides consistent outdoor propane heating for multi-fixture homes without occupying indoor space. Its low activation threshold and wired remote make it a practical choice for exterior installations.
Orbek 120,000 BTU Natural Gas Outdoor
Best for: outdoor natural gas installations needing remote control
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Flow Rate
- 5.1 GPM
- Installation Location
- Outdoor
- Dimensions
- 23.9 x 15.5 x 15.5 in
- Weight
- 29.3 pounds
This Orbek unit delivers 120,000 BTU and up to 5.1 GPM for outdoor natural gas installations. It measures 23.9 inches high and weighs 29.3 pounds. You get a remote and front display for temperature control. The flow rate depends on inlet water temperature and simultaneous demand. It suits homes needing reliable outdoor hot water with clear manual guidance for gas and venting connections.
Pros
- 120,000 BTU heating input for strong performance
- Includes remote control and front display for settings
- Outdoor-rated natural gas configuration
- Compact 15.5-inch width and 29.3-pound weight
Cons
- Outdoor placement limits winter usability in freezing climates
- Flow rate varies with inlet water temperature
- Requires professional installation and local code review
Good fit if
- You need an outdoor natural gas water heater
- You want remote temperature control convenience
- You have space for a 23.9-inch tall unit
Skip if
- You require an indoor installation only
- You need propane fuel instead of natural gas
- You want a compact unit under 15 inches wide
Verdict: Orbek 120,000 BTU Natural Gas Outdoor fits outdoor natural gas setups where remote control and 5.1 GPM output matter. It works well for single-family homes with adequate clearance and professional installation support.
Orbek 120,000 BTU Natural Gas Tankless Water Heater
Best for: flexible indoor or outdoor smart installations
- BTU
- 120,000 BTU (what this guide is about)
- Fuel Type
- Natural Gas
- Flow Rate
- 5.1 GPM
- Installation Location
- Indoor/Outdoor
- Voltage
- 120 V
- Temperature Control
- 95°F to 149°F, ±1°F
View on Amazon: Orbek 120,000 BTU Natural Gas Tankless Water Heater
This natural gas unit delivers 120,000 BTU and up to 5.1 GPM, making it suitable to supply hot water for two to four outlets simultaneously. You can mount it indoors or outdoors, and manage operation through Wi-Fi, voice control, or the included remote. It suits you if you need flexible venting options and precise temperature adjustments between 95°F and 149°F.
Pros
- Delivers 5.1 GPM flow rate with 0.53 GPM low-flow activation
- Supports both indoor and outdoor installation
- Includes Wi-Fi, mobile app, and Alexa voice control
- Adjustable temperature range from 95°F to 149°F within 1°F
Cons
- Outdoor installation requires an exhaust hood sold separately
- Requires a 120V electrical connection to operate
Good fit if
- You want app and voice management alongside remote control
- You need a natural gas heater capable of indoor or outdoor mounting
- You run two to four simultaneous outlets requiring up to 5.1 GPM
Skip if
- You plan an outdoor installation without purchasing extra exhaust parts
- You lack a 120V electrical outlet at your installation location
Verdict: Orbek 120,000 BTU Natural Gas Tankless Water Heater provides versatile indoor or outdoor placement paired with smart Wi-Fi control and a 5.1 GPM flow rate. It delivers steady temperatures across multiple household taps when paired with standard natural gas and 120V connections.
Specifications side by side
| Spec | APUS 5.43 GPM Propane Tankless Water Heater | MIZUDO 120K BTU WiFi Natural Gas Heater | NOVIEEX 5.3 GPM Outdoor Propane Tankless Water Heater | Novieex Indoor Natural Gas Tankless Water Heater | Ranein 5.1 GPM Condensing Natural Gas Water Heater | Westinghouse Outdoor Natural Gas Tankless Heater | VancEpic 5.1 GPM Propane Condensing Water Heater | Westinghouse Outdoor Propane 5.1 GPM Tankless Heater | Orbek 120,000 BTU Natural Gas Outdoor | Orbek 120,000 BTU Natural Gas Tankless Water Heater |
|---|---|---|---|---|---|---|---|---|---|---|
| Fuel Type | Propane | Natural Gas | Propane | Natural Gas | Natural Gas | not specified | Propane | Propane | Natural Gas | Natural Gas |
| Flow Rate | 5.43 GPM | 5.1 GPM | 5.3 GPM | 4.75 GPM | 5.1 GPM | not specified | 5.1 GPM | 5.1 GPM | 5.1 GPM | 5.1 GPM |
| BTU | 120,000 BTU | 120,000 BTU | 120,000 BTU | 120,000 BTU | 120,000 BTU | not specified | 120,000 BTU/hr | 120,000 BTU | 120,000 BTU/h | 120,000 BTU |
| Installation Location | Indoor | Indoor or Outdoor | Outdoor | Indoor | not specified | not specified | Indoor | Outdoor | Outdoor | Indoor/Outdoor |
| Voltage | 120V AC | not specified | 110V–120V AC | 110V–120V AC | 120V | not specified | not specified | 120 V AC | not specified | 120 V |
| Temperature Control | 95–149°F, ±1°F | ±1°F | 95°F–149°F, ±1°F | 95°F–149°F, ±1°F | 95°F–149°F, ±1°F | not specified | 95°F to 149°F | 95°F–158°F, ±1°F | not specified | 95°F to 149°F, ±1°F |
| Certification | not specified | CSA | not specified | not specified | ANSI Z21.10.3 | not specified | not specified | CSA, ANSI | not specified | CSA |
| Dimensions | 20.55 x 13.27 x 5.91 inches | 22.8 x 14.6 x 14.6 inches | 23.7" x 15" x 5.1" | not specified | 22 × 14.2 × 6.4 in | not specified | 9.25 x 20.2 x 20.2 inches | 23.9 x 15.5 x 7.3 in | 23.9 x 15.5 x 15.5 in | 22.83" x 14.57" x 7" |
| Use | not specified | Whole House | not specified | not specified | not specified | not specified | not specified | Whole House | not specified | not specified |
| Venting Type | not specified | not specified | not specified | not specified | Condensing | not specified | Condensing | Non-Condensing | not specified | not specified |
| Features | not specified | WiFi | not specified | not specified | not specified | not specified | not specified | not specified | not specified | not specified |
| Weight | 19.2 pounds | not specified | 34 pounds | 28.2 pounds | 26 pounds | not specified | not specified | not specified | 29.3 pounds | 25.6 pounds |
| Color | Space Gray | White 5.1NG | Gray | Pearl Grey | Gray | Deep Grey | Condensing | Grey 51PO | White | White |
| Model | AP-AWH-Q16LPG | FDG-CS120AW-NG | HS-20 | RS-18 | RH12KG-C-NG | HS120A1G-NG | RH12KG-C-LPG | AMZ-HS120A1G-LP | HS120 | HW120A1W-NG |
| Size | not specified | Indoor and outdoor | not specified | not specified | not specified | not specified | 5.1GPM, 120,000BTU, LPG | APOLO-120K | Large (5.1 GPM 120,000 BTU Outdoor) | not specified |
Is 120,000 BTU worth it for your home?
This heating power delivers up to 5.43 GPM of hot water. You get steady temperatures when running multiple fixtures simultaneously. The APUS and MIZUDO models show how this BTU level supports high flow rates for whole-house demand. If you only run one shower, this power may be overkill. However, homes with several bathrooms or laundry rooms benefit from the rapid recovery. Outdoor and indoor units alike use this output to maintain consistent heat under heavy use.
Worth it if
- You need hot water for multiple showers at once
- You have a large home with several bathrooms
- You want reliable flow rates during peak usage
Skip it if
- You only use one hot water fixture at a time
- Your home has low simultaneous demand
- You prefer smaller, lower-output units
If you also need outdoor heating, you can compare burner output across the best 48000 btu patio heaters.
How we selected units
We identified these models by scanning Amazon listings for the specific 120,000 BTU heating capacity. We only included products where this power level appears in the title or feature list. This ensures every unit can deliver the high flow rates required for whole-home use. We did not physically test these heaters. All details come directly from the published specifications on the product pages.
We ordered the results by availability first, then by overall rating weighted by count, and finally by how many of our criteria the specs meet. We show only one variant per product family to keep the comparison clear. Prices and stock levels update daily on the page and are not part of this text. You can trust this list reflects current market data for 120,000 BTU units.
How to choose the right 120000 BTU unit
-
Check your fuel source
Verify your home has the correct gas line before buying. Propane units like the APUS 5.43 GPM model work where natural gas is unavailable. Natural gas heaters, such as the MIZUDO or Novieex indoor options, require a direct connection to your existing gas supply. Using the wrong fuel type will prevent the unit from operating safely. Match the fuel type in the product attributes to your current home infrastructure to ensure compatibility and proper installation.
-
Decide indoor or outdoor
Installation location determines your venting needs and unit durability. Indoor models like the APUS or Novieex natural gas heater require specific venting systems to exhaust gases safely. Outdoor units, such as the Westinghouse or Orbek models, are built to withstand weather but need adequate clearance. Choose an indoor unit if you want to hide the hardware. Select an outdoor unit if you prefer easier maintenance and do not need complex venting runs through your home.
-
Match flow rate to usage
Flow rate indicates how many fixtures you can run at once. The APUS provides 5.43 GPM, supporting high-demand scenarios better than most others. The Novieex indoor natural gas model offers 4.75 GPM, which is sufficient for smaller households. Most other units deliver 5.1 GPM. If you plan to run a shower and kitchen sink simultaneously, aim for 5.0 GPM or higher. Check the GPM specification to ensure the unit meets your peak hot water demand.
-
Consider condensing efficiency
Condensing units recover heat from exhaust gases, improving efficiency. The Ranein and VancEpic models feature condensing technology, which often allows for simpler venting setups. These units are ideal for mid-sized homes or apartments where efficiency matters. Standard non-condensing units, like the Westinghouse outdoor propane heater, may require different venting materials. Check the venting type in the attributes. Condensing models can offer better performance in cold climates due to integrated freeze protection features.
-
Evaluate smart controls
Remote management adds convenience for monitoring and adjusting temperatures. The MIZUDO and Orbek models include WiFi capabilities for smartphone control. This feature allows you to adjust settings without accessing the unit physically. If you value precise temperature regulation from anywhere, look for WiFi in the features list. Units without this feature require manual adjustment on the device. Decide if remote access is a priority for your installation location and usage habits.
-
Verify elevation compatibility
Altitude affects gas combustion efficiency for many tankless heaters. Several models, including the Novieex indoor natural gas and Ranein units, are rated for elevations below 2,000 feet. If you live higher, you may need a de-rated unit or specific adjustments. Check the product description for elevation limits. Using a standard unit at high altitude can reduce performance. Ensure your home's elevation matches the manufacturer's specifications to maintain the advertised 120,000 BTU output and flow rates.
Frequently asked questions
Can a 120,000 BTU tankless heater supply hot water to multiple fixtures at once?
Yes. Units in this range deliver high flow rates to support simultaneous use. The APUS model provides 5.43 GPM, while the MIZUDO and Novieex indoor natural gas models offer 5.1 GPM and 4.75 GPM respectively. These outputs allow you to run showers and sinks together without significant temperature drops.
What is the difference between indoor and outdoor installation for these units?
Installation location dictates venting and weather protection. Indoor models like the APUS and Novieex natural gas heater require proper venting and are designed for interior spaces. Outdoor units, such as the Novieex propane and Westinghouse natural gas heaters, are built for exterior mounting and do not need indoor venting runs.
Do I need WiFi for a 120,000 BTU tankless water heater?
WiFi is optional but useful for remote management. The MIZUDO natural gas heater and the Orbek indoor/outdoor model feature built-in WiFi for smart control. Other units, like the APUS propane heater, rely on digital temperature controls without wireless connectivity. Choose based on your preference for remote monitoring.
Which fuel type is better for a 120,000 BTU system?
Your choice depends on your home’s gas infrastructure. Propane units like the APUS and Westinghouse outdoor propane models work where natural gas is unavailable. Natural gas models, including the MIZUDO and Orbek, suit homes with existing gas lines. Both fuel types deliver the same 120,000 BTU heating power.
How large is a 120,000 BTU tankless water heater?
Dimensions vary by brand and fuel type. The APUS propane unit measures 19.3 by 27.6 inches and weighs 19.2 pounds. The Novieex indoor natural gas model is more compact at 16 by 17.3 inches. Outdoor units like the Westinghouse propane heater are 15.5 by 23.9 inches.
Are condensing models more efficient than standard ones?
Condensing technology recovers heat from exhaust gases, improving efficiency. The Ranein natural gas heater and VancEpic propane unit use condensing venting to maximize heat retention. These models are suitable for mid-sized homes or apartments. Standard non-condensing units, like the APUS, rely on traditional venting methods.
Can these heaters be used at high elevations?
Some models are rated for elevations below 2,000 feet. The Novieex indoor natural gas heater and the Ranein condensing model specify this limit. The Novieex outdoor propane heater also notes this elevation constraint. Check the specific product data for your location, as higher altitudes may require derating.
What is the flow rate of a 120,000 BTU tankless heater?
Flow rates range from 4.75 to 5.43 GPM for these units. The APUS propane heater leads with 5.43 GPM. The MIZUDO, Novieex indoor natural gas, Ranein, Westinghouse, and Orbek models provide 5.1 GPM or 4.75 GPM. Higher flow rates support greater simultaneous fixture usage in your home.