Choosing a tankless water heater for an apartment means balancing hot-water needs with limited space, electrical capacity, and rental or building rules. The options below range from small under-sink units for one faucet to larger 240V models designed to serve multiple fixtures. Before buying, check your building’s electrical service and get approval from your landlord or property manager if needed.
Table of Contents
Quick Comparison
| Product | Power | Best suited for | Key detail |
|---|---|---|---|
| xwdzswgs 3,000W Tankless Water Heater | 110V, 3,000W | A single sink or point of use | Compact unit; not intended for showers |
| Garvee 18kW Tankless Water Heater | 240V, 18kW | Apartments with higher hot-water demand | Self-modulating power and digital controls |
| Westinghouse 14kW Tankless Water Heater | 240V, 14kW | Up to two points of use under stated conditions | Wi-Fi controls; requires a dedicated 60A circuit |
| Rheem 11kW Multi-Fixture Water Heater | 240V, 11kW | Small homes and modest multi-fixture needs | Digital temperature control; up to 2.68 GPM listed |
| ThermoMate 6kW Sink Water Heater | 240V, 6kW | One sink or other point-of-use use | Hardwired unit with a stated 1.0 GPM at a 35°F rise |
Our Picks: Best Tankless Water Heaters For Apartments reviews
1. xwdzswgs 3,000W: A Compact Choice for One Sink
This 110V, 3,000W unit is designed to provide hot water close to a faucet, such as at a kitchen or bathroom sink. Its wall-mounted format and compact size may help when cabinet or utility-room space is tight. A display shows operating information, and the controls allow temperature readings in Fahrenheit or Celsius.
The listed output is modest: the product description gives temperature-rise figures at 0.3 and 0.5 gallons per minute. It also specifically says the unit is not suitable for showers, which typically need at least 1.8 GPM. Think of it as a point-of-use helper rather than a replacement for an apartment’s main water heater.
The 110V connection may sound simpler than a larger 240V model, but installation still needs to follow the instructions and local requirements. The unit must be installed vertically, and its water and electrical connections should be handled safely. It is a more limited option than the 240V heaters below, but that may be an advantage if you only want hot water at one sink.
Pros:
- Compact wall-mounted design for tight spaces
- Uses a 110V supply
- LED display and Fahrenheit/Celsius selection
- Listed protections include dry-boil and overheat protection
Cons:
- Not suitable for showers
- Low stated flow makes it a point-of-use option, not a whole-apartment solution
Verdict: Choose this model if you need a compact hot-water source for a single sink and do not expect it to serve a shower or several fixtures.
2. Garvee 18kW: More Capacity for Multiple Fixtures
The Garvee is an 18kW, 240V model intended for more hot-water demand than a small under-sink heater can handle. Its product description says it can serve two to three fixtures at once, though the actual result in your apartment will depend on incoming water temperature, the temperature setting, and how much water each fixture uses.
Self-modulating controls adjust power based on demand, and the digital display lets you set the temperature from 86°F to 140°F. The compact, wall-mounted case can save floor space compared with a tank-style heater. The listing also describes overheat, anti-freeze, and leak-prevention protections and states that the unit is ETL certified.
The main question is whether your apartment’s electrical service can support an 18kW heater. A high-output electric tankless model can require substantial wiring and circuit capacity, so “easy installation” should not be taken as a reason to connect it without an electrical assessment. This is a stronger candidate for an owner-approved installation than for a renter seeking a simple swap.
Pros:
- Higher listed output than the point-of-use models here
- Self-modulating power and adjustable digital temperature controls
- Space-saving wall-mounted design
- Listed safety features include overheat and leak prevention
Cons:
- Requires 240V power and may exceed an apartment’s available electrical capacity
- Actual simultaneous flow depends on water temperature and fixture demand
Verdict: Consider the Garvee if you need more than sink-only hot water and a qualified electrician confirms your apartment can support its 18kW load.
3. Westinghouse 14kW: Smart Controls in a Slim Package
This 14kW Westinghouse is a compact 240V heater with Wi-Fi features and a stated maximum flow of 3.4 GPM under specific conditions: a 62°F inlet temperature and a 105°F outlet setting. The listing says that output can support two points of use at once. Cooler incoming water or heavier demand can reduce the flow available at a comfortable temperature.
You can adjust settings through a mobile app or compatible voice-control systems, and the temperature-memory feature is designed to restore the previous setting after a power outage. Its listed protections include leakage, overheating, dry-fire, and over-voltage protection. The manufacturer also gives dimensions of 12.59 inches high, 9.56 inches wide, and 3.28 inches deep, which may help when planning a tight installation area.
Electrical requirements deserve close attention: the supplied specifications call for a dedicated 60A double-pole breaker and 6 AWG wire at 240V. Those requirements may be difficult to meet in some apartment panels. Compared with the Rheem 11kW, this model has more listed output and app controls, but it also calls for a larger dedicated circuit.
Pros:
- Wi-Fi, app, and compatible voice-control features
- Listed flow of up to 3.4 GPM under specified conditions
- Compact wall-mounted dimensions
- Temperature memory and multiple listed safety protections
Cons:
- Requires a dedicated 60A double-pole breaker and 6 AWG wire
- Maximum flow depends on inlet temperature and outlet setting
Verdict: Pick the Westinghouse if app control matters to you and your electrical system can meet its stated circuit requirements.
4. Rheem 11kW: A Practical Mid-Range Multi-Fixture Option
Rheem’s 11kW model is a 240V electric heater designed for multiple fixtures. The listed maximum is up to 2.68 GPM, and the digital thermostat adjusts in one-degree steps from 80°F to 140°F. That level of adjustment can help you set a comfortable temperature, but the available flow still depends on the incoming water temperature and how many fixtures are running.
Like other tankless electric models, it heats water on demand and does not need a vent. Its compact design can free up floor space compared with a traditional tank. Rheem specifies one 50A double-pole breaker, #8 AWG copper conductors with ground, and a recommended minimum 100A household electrical service panel. Check those requirements before treating it as a straightforward replacement.
Compared with the 14kW Westinghouse and 18kW Garvee, the Rheem has lower listed output and fewer connected features. Its more moderate capacity may suit a small apartment with restrained simultaneous use, provided the electrical service is adequate. The listed warranty is five years for leaks and one year for parts.
Pros:
- Up to 2.68 GPM listed for multi-fixture use
- Digital temperature control in one-degree increments
- No venting required
- Compact design helps preserve floor space
Cons:
- Requires a 240V circuit and a recommended minimum 100A household service panel
- Lower listed output than the 14kW and 18kW choices
Verdict: The Rheem is a sensible mid-range candidate for an apartment with modest multi-fixture needs, but only after confirming the electrical requirements.
5. ThermoMate 6kW: A Dedicated Heater for a Sink
The ThermoMate is a small point-of-use heater made for a sink, not a full apartment. Its 6kW heating system is listed to provide 1.0 GPM at a 35°F temperature rise. The unit has a digital display and touch controls, with temperature adjustments in one-degree increments from 85°F to 131°F.
At about 11 inches high, 7.4 inches wide, and 2.5 inches deep, it can fit beneath a sink or in another tight space. The product description lists a stainless-steel water tube and a cast-aluminum heating element separated from the water line. It is a 240V hardwired unit, with a stated requirement for a 30A circuit breaker and at least 10 AWG wire.
That hardwired setup may call for more work than a plug-in appliance, and it must be sized for the job. Compared with the 110V xwdzswgs, the ThermoMate has a higher stated flow at its specified temperature rise, but it still is not a whole-apartment heater. It makes the most sense when you want to reduce the wait for hot water at one faucet.
Pros:
- Small footprint for under-sink installation
- Stated 1.0 GPM at a 35°F temperature rise
- Digital display and one-degree temperature adjustment
- Self-modulating power is listed
Cons:
- 240V hardwired installation requires a 30A breaker and at least 10 AWG wire
- Designed for point-of-use service, not whole-apartment demand
Verdict: Choose the ThermoMate for a dedicated sink application if you can meet its hardwiring requirements and do not need shower or multi-fixture service.
How to Choose a Tankless Water Heater for an Apartment
Decide Whether You Need Point-of-Use or Whole-Apartment Hot Water
Start by identifying the fixture you want to serve. The 3,000W xwdzswgs and 6kW ThermoMate are point-of-use options intended for a sink or similar limited demand. The 11kW, 14kW, and 18kW models are positioned for broader use, but their ability to serve multiple fixtures depends on flow and incoming water temperature. A small heater at one faucet will not replace a central water heater for showers and other fixtures.
Check Your Electrical Panel and Circuit Requirements
Match the heater’s voltage, breaker, and wire requirements to your apartment’s electrical system before ordering. The larger models in this group use 240V power, and the Westinghouse, Rheem, and ThermoMate listings specify particular circuit and wiring needs. An electrician can assess whether the panel has enough capacity and whether new wiring is needed. Do not assume that a heater will work simply because your apartment has 240V service.
Estimate Flow and Temperature Rise
Tankless output depends on how much water the unit must heat and how many fixtures draw water at once. A higher temperature rise can reduce the flow available, while colder incoming water makes the heater work harder. Compare the manufacturer’s stated flow figures at their stated temperature conditions with your actual needs. Treat maximum GPM claims as conditional rather than guaranteed in every apartment.
Get Permission and Check Building Rules
In a rental, ask your landlord or property manager before changing plumbing or electrical equipment. Condos and co-ops may also have rules about alterations, access to shared systems, and approved contractors. Confirming permission first can help you avoid an installation that is not allowed or cannot be safely supported by the building.
Plan the Installation Location
Measure the available wall or cabinet space and check the required orientation, water connections, and access for service. The 110V xwdzswgs listing requires vertical installation, while the other products have their own installation directions. Keep the area accessible for shutoffs and maintenance, and follow the manufacturer’s clearances and moisture guidance.
Consider Maintenance and Water Conditions
Tankless heaters need care even though they do not store a tank of hot water. The Garvee description calls for periodic cleaning of its inlet filter, and mineral buildup can affect water-heating equipment over time. Check the unit’s maintenance instructions and consider local water conditions when deciding whether a particular model is a good fit.
Frequently Asked Questions
Can a tankless water heater work in an apartment?
Yes, if the unit fits the apartment’s electrical, plumbing, and space requirements and the building allows the installation. A point-of-use model may be suitable for one sink, while a larger 240V model may serve more fixtures if the electrical service supports it.
Which of these heaters can serve a shower?
The 110V xwdzswgs model is specifically described as unsuitable for showers. The other models have higher listed outputs, but whether one can serve your shower depends on incoming water temperature, desired outlet temperature, and flow. Verify the sizing with the manufacturer’s specifications and an installer.
Is a 110V tankless heater enough for a whole apartment?
The 110V, 3,000W model in this list is intended for limited point-of-use service, not a whole apartment. Its stated flow and the product’s shower warning make it a better match for a single faucet than for bathing or several fixtures.
Will a 240V heater automatically provide more hot water?
Not by itself. Output depends on the heater’s power, the temperature rise required, and the amount of water being used. A 240V unit also needs a suitable circuit and enough capacity in the apartment’s electrical panel.
Can I install one of these heaters myself?
Installation involves electrical and plumbing connections, and several models require hardwiring or dedicated circuits. Follow the manufacturer’s instructions and local codes, and use qualified professionals where required. Renters should get written approval before making changes.
What is the difference between a point-of-use and a whole-home model?
A point-of-use heater supplies hot water close to one faucet or fixture. A larger whole-home or multi-fixture unit is intended to serve more of the plumbing system, but it needs enough capacity for the combined flow and temperature rise. The small sink models in this guide should not be treated as whole-apartment replacements.
Final Recommendation
For a single sink, the ThermoMate 6kW offers a higher stated point-of-use flow than the 110V xwdzswgs, while the xwdzswgs may suit a more limited setup where its 110V design is useful. For broader apartment hot-water needs, compare the Rheem 11kW, Westinghouse 14kW, and Garvee 18kW against your expected fixture use and electrical capacity. The best choice is the one your building can safely support—not simply the model with the highest wattage.
