The best tankless water heater for a one-bedroom apartment depends on whether you need hot water for one sink or several fixtures. The Rheem 24kW is the highest-capacity option listed, while the Westinghouse 14kW adds Wi-Fi controls. The 3,000W 110V model is aimed at point-of-use installations, and the Rheem 8kW is a lower-output choice for limited demand. Check incoming water temperature, electrical capacity, and local installation requirements before selecting a unit.
| Product | Best For | Listed Output |
|---|---|---|
| Rheem RTEX-24 24kW | Higher demand across multiple fixtures | Up to 5.9 GPM |
| Westinghouse 14kW | Smart controls and moderate demand | Up to 3.4 GPM under stated conditions |
| Rheem 18kW | Midrange capacity with digital control | Up to 4.4 GPM |
| Rheem 8kW | Lower demand and smaller applications | Up to 1.95 GPM |
| 110V 3,000W model | Point-of-use sink installation | Temperature rise varies by flow |
Rheem RTEX-24 24kW Electric Tankless Water Heater
The Rheem RTEX-24 is the highest-output model in this selection. Its listed maximum flow is up to 5.9 gallons per minute, and the product is described for multiple-fixture applications. That makes it the best fit here for an apartment where more than one hot-water outlet may be used, provided the electrical supply and incoming water conditions support the required output.
Choose this model if capacity is the priority and a qualified installer confirms the unit is correctly sized. Rheem advises buyers to verify electrical requirements and select a properly sized heater. A tankless unit’s actual hot-water flow depends on the temperature rise needed, so the maximum GPM should not be treated as a guarantee for every apartment.
Limitation: Its 24kW rating makes electrical requirements especially important. Avoid choosing it based on maximum flow alone; verify the apartment’s service and circuit capacity before purchase.
Westinghouse 14kW Wi-Fi Tankless Water Heater
The Westinghouse 14kW model is best for buyers who want app-based or voice-enabled temperature controls and a stated flow suitable for moderate use. The manufacturer lists a maximum of 3.4 GPM when inlet water is 62°F and the outlet is set to 105°F, and says it can support two water points simultaneously under those conditions. It also lists a 0.53 GPM minimum startup flow.
Smart-home features include Wi-Fi adjustment through an app, Alexa and Google Home compatibility, and temperature memory that restores the prior setting after a power outage. Its compact wall-mounted dimensions are listed as 12.59 inches high, 9.56 inches wide, and 3.28 inches deep.
Limitation: This unit requires a dedicated 60A double-pole breaker and 6 AWG wire at 240V, according to the product details. Choose it only after confirming the electrical installation requirements.
Rheem 18kW Electric Tankless Water Heater
The Rheem 18kW is a middle-capacity choice for apartment buyers who want more listed flow than the 8kW option but do not need to start with the 24kW model. Its stated maximum is up to 4.4 GPM. The unit has an external digital thermostat with an LED display and temperature control accuracy listed as plus or minus one degree.
Rheem also lists self-modulation, which adjusts power to meet hot-water demand, and copper immersion heating elements described as field-serviceable. These features make this model worth considering when digital temperature setting and serviceable components are priorities.
Limitation: The listed 4.4 GPM is a maximum, not a guaranteed flow at every incoming water temperature. The available product details do not specify the circuit requirements, so confirm them with the manufacturer or an electrician before installation.
Rheem 8kW Multi-Fixture Tankless Water Heater
The Rheem 8kW is best for a one-bedroom apartment with modest hot-water demand or a limited-use application. Its listed maximum is up to 1.95 GPM, and Rheem describes it as suitable for multiple-fixture applications. In practice, the relatively low maximum flow means it is a better match for careful, limited use than for several high-demand outlets operating together.
Like the larger Rheem models in this list, it is designed to provide on-demand hot water while taking up less space than a storage tank. The manufacturer advises buyers to size the heater for the home and verify electrical requirements before installation.
Limitation: The 1.95 GPM maximum is lower than the other full-size models listed here. Consider a higher-output option if simultaneous hot-water use is an important requirement.
110V 3,000W Point-Of-Use Water Heater
This compact 110V model is best for buyers seeking a point-of-use heater, such as for a sink, rather than a high-capacity whole-apartment replacement. Its 3,000W rating, wall-mounted design, and digital display are suited to installations where space is limited. The listing states that it can raise water temperature by 82°F at 0.3 GPM and 131°F at 0.5 GPM.
The display can show Fahrenheit or Celsius, and the listed protections include leakage protection, dry-boil protection, overheating cutoff, and automatic shutoff during inactivity. The product details also describe an IPX4 rating and water-and-electricity isolation.
Limitation: The stated temperature-rise figures are tied to low flow rates. This model is not the best choice when you need substantial flow at multiple fixtures. Confirm its electrical and plumbing suitability for the intended location.
Buying Guide: How To Choose An Apartment Tankless Water Heater
A one-bedroom apartment does not automatically need a small heater. The right capacity depends on how many hot-water outlets you use at once, the temperature of the water entering the heater, and how much the water must be heated. Compare the unit’s output under realistic conditions rather than relying only on its kilowatt rating or highest advertised flow.
How much hot water do you need at once?
List the fixtures that may run simultaneously, such as a shower, kitchen faucet, and bathroom sink. Add their expected hot-water flow to estimate the demand. If your household usually uses one fixture at a time, a lower-output unit may be adequate. If showering and sink use overlap, compare models with higher stated flow and check the conditions behind those figures.
Maximum GPM is not the same as a guaranteed flow for every home. A colder incoming water supply requires a greater temperature rise, which can reduce the flow available at the desired output temperature. Ask an installer to assess local winter inlet temperatures and your preferred hot-water setting.
Will your apartment’s electrical service support it?
Electric tankless heaters can require substantial electrical capacity. Check the voltage, breaker, wiring, and available service before selecting a model. The Westinghouse listing specifies a dedicated 60A double-pole breaker and 6 AWG wire at 240V. Other products in this list also require buyers to verify electrical requirements, but the supplied product information does not provide complete circuit details for every model.
Apartment residents should also confirm whether they are allowed to alter electrical or plumbing systems. Get approval from the property owner or manager where required, and have a qualified electrician or plumber assess the installation. Do not assume that a standard outlet or existing heater connection is sufficient.
Do you need a whole-apartment unit or point-of-use heat?
A whole-apartment heater is intended to serve the home’s hot-water system. A point-of-use model is placed near a particular outlet and may suit a sink or other limited-demand location. The 110V 3,000W product is described as compact and intended for settings including kitchens and apartments, but its listed temperature rises are at low flow rates. It is therefore a different type of choice from the 14kW, 18kW, and 24kW models.
Consider pipe distance as well as heater output. A tankless heater cannot eliminate the time it takes water already sitting in a long pipe to reach a faucet. A point-of-use installation may reduce that wait at its own outlet, but confirm the plumbing layout and intended use before buying.
Which features matter for everyday use?
- Temperature controls: A digital display can make setpoint adjustments easier. The Rheem 18kW lists an external digital thermostat and LED display.
- Smart controls: The Westinghouse 14kW lists app control and compatibility with Alexa and Google Home. Choose these features only if remote or voice adjustment is useful to you.
- Physical size: Wall-mounted designs can preserve floor space, but confirm clearance and connection needs at the installation location.
- Protection features: Review the exact protections listed for the model. Do not assume every unit includes the same safeguards.
- Service considerations: Product descriptions may identify serviceable components, but installation and maintenance needs vary. Consult the manufacturer’s instructions.
What should you verify before ordering?
Confirm the exact model, voltage, required circuit, dimensions, plumbing connections, permitted installation location, and local code requirements. Ask for a sizing calculation based on the apartment’s incoming water temperature and simultaneous fixture demand. If the listing’s flow rate is shown for a specific inlet and outlet temperature, use those conditions when comparing it with other products.
Also check whether the product is intended to replace the apartment’s central water heater or serve a single fixture. The distinction affects both performance expectations and the plumbing work required. A professional assessment can help prevent selecting a heater that cannot deliver the desired flow or that exceeds available electrical capacity.
Frequently Asked Questions
What size tankless water heater is suitable for a one-bedroom apartment?
There is no single size for every one-bedroom apartment. Choose based on simultaneous fixture demand, incoming water temperature, desired outlet temperature, and available electrical capacity. The listed options range from a 3,000W point-of-use model to 24kW whole-home-style units.
Can a 3,000W 110V heater supply an entire apartment?
The product details emphasize compact and point-of-use applications and give temperature-rise figures at 0.3 and 0.5 GPM. Those specifications do not establish it as a suitable whole-apartment heater. Confirm the intended use and flow needs before selecting it.
Does a higher GPM rating always mean better performance?
No. A stated maximum flow depends on test conditions, including inlet and outlet temperatures. A colder water supply may reduce available flow at the same target temperature. Compare ratings using similar conditions and your household’s actual demand.
Can I install an electric tankless heater in an apartment myself?
Electrical and plumbing requirements vary by model and location. Check property rules and local codes, and use qualified professionals to assess installation. The Westinghouse model, for example, specifies a dedicated breaker and wire size at 240V.
Which listed model has smart-home controls?
The Westinghouse 14kW model lists Wi-Fi app controls and compatibility with Alexa and Google Home. Its details also describe temperature memory after a power outage.