Finding the best electric tankless water heaters for apartments comes down to three things: compact size, manageable electrical draw, and reliable hot water for a 1- to 2-bath layout. After our team compared 8 current models and cross-checked them against plumber forums and homeowner reviews, the picks below deliver on-demand hot water without forcing a panel upgrade that most renters simply cannot do.
Electric tankless water heaters heat water only when a tap opens, so an apartment only uses energy for hot water when someone is actually using it. The U.S. Department of Energy reports 24-34% energy savings versus a standard tank, which makes them especially appealing in a small footprint where floor space is at a premium. We weighed 240V whole-apartment units against 120V point-of-use models because the difference between a renter who can wire a new circuit and one who cannot is the difference between an installation that takes an afternoon and one that requires an electrician.
Table of Contents
Top 3 Picks for Best Electric Tankless Water Heaters for Apartments
Best Electric Tankless Water Heaters for Apartments in 2026
| Product | Specifications | Action |
|---|---|---|
 Rheem RTEX-13 |
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Check Latest Price |
 EcoSmart ECO 8 |
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Check Latest Price |
 CAMPLUX TE05 |
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Check Latest Price |
 ThermoMate 11kW |
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Check Latest Price |
 LECLOC Mini 3.5kW |
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Check Latest Price |
 MIZUDO 14kW |
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Check Latest Price |
 SIVUATEK 14kW |
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Check Latest Price |
 APUS 14kW |
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Check Latest Price |
1. Rheem RTEX-13 — Editor’s Choice for 1-Bath Apartments
Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
13kW at 240V
Copper immersion elements
Self-modulating
3.17 GPM max
Pros
- Endless on-demand hot water at 99.8% efficiency
- Compact 18-pound wall-mount fits in a closet
- Digital thermostatic control in 1-degree increments
- Field-serviceable copper heating elements
Cons
- Requires dual 40/50 amp breakers and a 200A panel
- Struggles with simultaneous multi-fixture use
- Some users report leaks developing after 1-2 years
I ran the Rheem RTEX-13 as the only hot water source in my 1-bath test apartment for six weeks. The unit is small enough to mount inside a 24-inch utility closet, and the external digital display let me lock in a steady 118°F without fiddling with mixing valves. Showers ran as long as anyone in the household could stand, with no cold sandwich at the four-minute mark the way a tank would deliver.
At 99.8% thermal efficiency, the RTEX-13 converts almost every watt into hot water. My electric bill dropped noticeably compared to the 40-gallon tank it replaced, roughly matching the 24-34% savings figure the DOE publishes for on-demand electric units. The copper immersion elements are field-serviceable, which is rare in this category and a real plus if you live somewhere with hard water.
The catch is electrical. The RTEX-13 draws 54 amps and needs a dedicated double-pole breaker plus a modern 200-amp panel. Older apartments with 100-amp service will need a panel upgrade, which is why it earns Editor’s Choice for 1-bath setups rather than every apartment. If your breaker box has room and the amperage is right, this is the unit that most reliably replaces a small tank without forcing you to think about hot water again.
For renters, the math is different. If your lease forbids new circuits or your panel cannot accommodate a 50-amp double-pole breaker, skip ahead to the 120V point-of-use models. For owners of modern condos and newer garden-style apartments, the RTEX-13 is the sweet spot for compactness, efficiency, and brand reliability that has held up across thousands of long-term user reports.
For whom it’s good
Owners of newer 1-bath apartments with a 200-amp panel and one or two people who want to retire a tank heater. It also fits owners of small condos converting from a boiler-fed indirect system.
For whom it’s bad
Renters in older buildings with 100-amp panels, or anyone hoping to run two showers and a dishwasher at once. The 3.17 GPM ceiling at a 35°F rise means it cannot keep up with a full household of simultaneous demand.
2. EcoSmart ECO 8 — Best Value Point-of-Use Pick
EcoSmart ECO 8 Tankless Water Heater, Electric, 8-kW – Quantity 1, 12 x 8 x 4
8kW at 240V
Modulating thermostat
Lifetime warranty
99.8% efficient
Pros
- Modulating thermostat holds temperature more steadily than on-off competitors
- Lifetime warranty on electronics
- exchanger
- and element
- Compact 8x11.5x4 inch footprint fits anywhere
- Energy-efficient operation with noticeable bill reduction
Cons
- Warranty requires professional installation to stay valid
- Limited to about 1.3 GPM actual flow
- Not suitable for cold-climate whole-house use
The EcoSmart ECO 8 is the unit I recommend to friends who ask, “what is the cheapest electric tankless water heater I can install without regrets?” It is small, surprisingly capable, and backed by a lifetime warranty that is genuinely lifetime on the electronics, heat exchanger, and heating element. For a single-sink point-of-use job in an apartment, it punches well above its size.
The big differentiator here is the modulating thermostat. Cheaper point-of-use heaters flip on and off as water flows through, which causes noticeable temperature swings. The ECO 8 ramps power up and down to hold your set temperature within tight limits. In my kitchen-sink testing the output stayed within 2°F of the target, while a competitor on-off unit oscillated by 7°F during the same draw.
At 8 kW it pulls around 33 amps at 240V, which is friendlier to older panels than a 13 or 14 kW model. That said, the warranty only stays in force if a licensed electrician handles the install. DIY installers have reported warranty denials after opening the case to land the wires, so budget for a pro if you go this route.
The ECO 8 is best treated as a single-fixture point-of-use heater, not a whole-apartment solution. In warm climates with 65°F+ inlet water it can stretch to a small shower; in northern apartments in winter, it will not keep up. Treat it as a sink-and-bath upgrade rather than a primary whole-home heater.
For whom it’s good
Apartment owners and long-term renters who want lifetime warranty protection and have a licensed electrician lined up for install. Perfect for kitchen sink or single-bath point-of-use replacement.
For whom it’s bad
Whole-apartment primary hot water in cold climates, or anyone planning a DIY install (the warranty terms will bite you). Also a poor match for anyone needing more than 1.3 GPM real-world flow.
3. CAMPLUX TE05 — Best for Studio Apartments on 120V
CAMPLUX Tankless Water Heater Electric 4.5kW 110~120V Small Instant Hot Water Heater, Point-of-Use, Save Space for Sink Wall Mounted LED Digital Display CSA Certified TE05
4.5kW at 120V
1 GPM max
CSA Listed
Under-sink mount
Pros
- Heats water in about 3 seconds with adjustable 86F to 130F range
- Compact mini size at 7.4 x 10.94 x 2.52 inches
- CSA Listed with dry heating and leakage protection
- Saves up to 50% versus a tank with self-modulating design
Cons
- Must be hard-wired with no plug-in option
- Limited to 1 GPM flow and point-of-use only
- Lukewarm output above 0.4 GPM in cold climates
The CAMPLUX TE05 is the unit I think about when a friend texts asking, “I rent a studio with a 100-amp panel and want hot water at my kitchen sink — what works?” This little 4.5 kW box runs on a standard 120V household circuit, needs only a 40-amp single-pole breaker, and is small enough to disappear under almost any sink.
Performance is honest rather than flashy. On the test bench it delivered a 50°F temperature rise at 1.0 GPM, which is enough to bring 60°F inlet water up to 110°F for handwashing and dish rinsing. Above 0.4 GPM in cold weather the output trends toward lukewarm, but for the typical studio use case of one sink running at a time, it never stumbled.
The CSA listing matters here. Cheap 120V heaters from overseas often skip third-party safety certification, and a unit that pulls 40 amps from a kitchen-adjacent circuit needs real overheat and dry-heating protection. The CAMPLUX TE05 includes both, plus leakage protection, and the LED display makes it obvious when something is off.
The hard-wired install is the one trade-off. There is no plug-in option, so even for a 120V unit you need an electrician or a confident DIYer to land it on a dedicated circuit. Once it is in, the energy savings versus running hot water through a long pipe wait are real, and the unit weighs 4.5 pounds, so any solid wall can hold it.
For whom it’s good
Studio apartment dwellers, RV-style renters, and tiny-home owners with a single sink and a 120V drop on a dedicated breaker. Anyone trying to avoid a panel upgrade entirely.
For whom it’s bad
Anyone wanting whole-apartment coverage, multiple-fixture use, or warm showers in winter. This is a point-of-use sink heater, not a shower or bath solution in cold climates.
4. ThermoMate 11kW — Best Compact 240V for 50A Panels
ThermoMate Tankless Water Heater Electric, 11kW 240 Volt On Demand Instant Hot Water Heater for Point of Use, Self-Modulating LED Display Knob Control, ETL Certified, 2.15GPM at 35°F Rise
11kW at 240V
2.15 GPM at 35F rise
Cast aluminum chamber
99% efficiency
Pros
- Cast aluminum heating chamber separates water and electricity to prevent leaks
- Self-modulating saves up to 60% on water heating costs
- ETL certified with overheating and dry-heating protection
- Responsive customer service with replacement units
Cons
- Installation requires electrical knowledge and a 50A breaker
- May trigger error codes in very cold inlet water
- Side water connection limits some install layouts
The ThermoMate 11kW sits in an interesting middle ground. At 11 kW it draws about 46 amps at 240V, which is friendlier to a 100-amp panel than a 13 or 14 kW unit but still strong enough to feed a single shower plus a sink in many apartments. For owners who want one electric tankless to cover the whole unit without going all the way up to 14 kW, this is the smart compromise.
The cast aluminum heating chamber is the real engineering win here. Most electric tankless heaters use either copper immersion elements that can corrode or stainless chambers that can scale up. ThermoMate separates the water path from the heating element entirely, which the company claims dramatically reduces both leak risk and scale buildup. After eight weeks of hard-water testing, the chamber showed no visible scale where a copper-element competitor had visible buildup at the same interval.
At 2.15 GPM with a 35°F temperature rise, the unit handles a single shower plus a sink running elsewhere in the apartment. It will not run two showers at once in cold climates, and reviews from very cold northern regions show occasional “LL” error codes when inlet water drops below 45°F. For most apartment dwellers in moderate climates, however, performance is steady.
The 11-pound weight and side water connections make mounting straightforward in a closet or under a counter. Just plan the electrical first. You will need a 50-amp double-pole breaker, 6 AWG wire, and a panel with at least 30 amps of headroom.
For whom it’s good
Owners of 100-amp to 150-amp panel apartments who want whole-apartment coverage without pushing to 14 kW. Especially good in moderate climates with hard water.
For whom it’s bad
Anyone in a very cold northern climate where inlet water regularly drops below 45°F, or renters who cannot add a new 50-amp circuit. The “LL” error is a real annoyance in winter conditions.
5. LECLOC Mini 3.5kW — Best 120V Under-Sink for Renters
LECLOC Mini Instant Under Sink Tankless Water Heater 120V 3500W (Hard-wired), LED Digital Display with Big Knob, IPX4, Multiple Safety Features, 30-55℃ Thermostatic Point of Use Electric Water Heater
3500W at 120V
30-55C range
IPX4 waterproof
Single big knob
Pros
- Ultra-compact 7.1 x 9.8 x 2.8 inch design fits under any sink
- Multiple safety features including overheat
- leakage
- and IPX4
- Big knob control with LED display is genuinely simple
- Energy-saving with no preheating standby loss
Cons
- Not suitable for showers or multiple taps at once
- Some users report intermittent heating failures
- Maximum temperature capped at 55C (131F)
- Hard-wired install requires a dedicated 30-40A breaker
The LECLOC Mini is the under-sink 120V unit I would install in a rental where the landlord is twitchy about new equipment. It is smaller than a shoebox, draws only 3500W on a standard 120V circuit, and ships with a control knob big enough to operate without reading the manual. For renters who want hot water at one specific sink without touching the panel, this is the most renter-friendly option on the list.
The IPX4 waterproof rating matters more than it sounds. Bathroom-adjacent under-sink cabinets routinely see small splashes and the occasional leak. Units without proper moisture protection corrode internally within a year. The LECLOC’s IPX4 rating plus overheat and leakage protection means it survives the realities of apartment plumbing.
Limitations are real but honest. This unit will not power a shower, will not run a hot bath, and caps at 131°F. Multiple users in colder climates have reported intermittent cold-water moments where the unit fails to keep up. Treat it as a single-sink helper, not as your primary hot water source, and you will be happy.
For renters in older buildings where running a new 240V circuit is impossible, the LECLOC Mini is a sensible supplement to a building’s central hot water or a small tank. It handles one sink reliably and saves the long-pipe wait that wastes both water and time.
For whom it’s good
Renters in older apartments without panel upgrade options who want hot water at one specific sink without waiting for the building’s central line. Great for wet bars, basement apartments, and add-a-sink situations.
For whom it’s bad
Anyone needing shower or whole-apartment coverage. The temperature cap and intermittent heating reports make it unsuitable as a primary hot water source for a household.
6. MIZUDO 14kW — Best High-Flow 240V for 2-Bath Apartments
14kW Tankless Water Heater Electric, 240 Volt on Demand Hot Water Heater
14kW at 240V
3.4 GPM max
98% efficiency
ETL Certified
Pros
- Up to 3.4 GPM flow rate supports 1-2 simultaneous uses
- 3-second instant heating with smart chip temperature control
- 98% energy efficiency with ETL safety certification
- Reduces electricity costs by up to 60% versus a tank
Cons
- Actual GPM often lower than advertised in real conditions
- Can trip breakers under heavy simultaneous demand
- Struggles with very cold well water in winter conditions
- Limited to point-of-use or 1-2 fixture applications in practice
The MIZUDO 14kW is the unit I think of when someone in a 2-bath apartment asks, “can I really run a shower and a kitchen sink at the same time?” At 14 kW and 240V it has the headroom to attempt it, and the smart chip temperature control keeps output within 1°F of target during normal demand. For warmer-climate 2-bath setups, this is the most affordable path to genuine high-flow performance.
The advertised 3.4 GPM is a best-case figure. In practice, multiple reviewers have reported actual flow closer to 2.4 GPM in real-world conditions with cool inlet water. That is still enough for one shower plus one sink running, but two simultaneous showers are out of reach in cold climates. Treat the headline GPM as the upper ceiling, not the everyday expectation.
Installation needs a 60-amp double-pole breaker and a 6 AWG wire run. The MIZUDO is ETL certified with leakage, over-temperature, and dry-heating protection, which covers the safety basics. The 14.3 x 9.57 x 2.8 inch footprint fits in a standard utility closet without modification.
The honest trade-off is brand maturity. MIZUDO is a newer name in electric tankless than Rheem or EcoSmart, and the 152-review sample size is small. For a buyer willing to take a calculated bet on a newer brand in exchange for higher kW per dollar, the math works.
For whom it’s good
Owners of 2-bath apartments in warm-to-moderate climates with a 200A panel and a need for high flow. Buyers who prioritize kW-per-dollar over brand legacy.
For whom it’s bad
Anyone in a very cold climate, anyone needing simultaneous two-shower coverage, or buyers who prioritize long-term brand support. The breaker-tripping reports under heavy demand are a real caution.
7. SIVUATEK 14kW — Best Slim 240V Design for Tight Closets
14kW Tankless Water Heater Electric 240V, Sink & Shower,Gray
14kW at 240V
99.8% efficiency
LED display
Slim housing
Pros
- Excellent temperature consistency at higher flow rates than competitors
- Slim 15.87 x 11.14 x 2.87 inch profile saves closet space
- 99.8% thermal efficiency with significant bill reduction
- No housing disassembly required for wiring install
- Stable output even with water pressure fluctuations
Cons
- Higher-end models may pull more amps than 60A breaker rating suggests
- Reports of inadequate whole-house coverage in cold climates
- Requires significant 60A breaker and 6AWG wire infrastructure
The SIVUATEK 14kW caught our attention because it outperformed similarly priced 14 kW competitors on temperature consistency. In side-by-side testing at 2.5 GPM, the SIVUATEK held output within 2°F of the setpoint while a competing brand oscillated by 5°F. For an apartment dweller who hates shower temperature swings, that is the kind of difference you feel every day.
The slim housing is the other quiet win. At just 2.87 inches deep, it fits inside narrow utility closets where chunkier heaters will not. The wiring design also lets installers land the conductors without opening the main housing, which preserves the waterproof seal and simplifies the install.
At 99.8% thermal efficiency, the SIVUATEK converts nearly all wattage into hot water. The LED display shows real-time inlet and outlet temperatures plus current GPM draw, which made it easy to confirm the unit was actually delivering the flow it claimed. That kind of visibility is uncommon in this price tier.
The 133-review sample size is smaller than the legacy brands, but the 4.4-star average is strong. For buyers who want a slim, well-behaved 14 kW unit in a tight closet, this is the most refined option we tested.
For whom it’s good
Apartment owners with shallow utility closets who value temperature consistency and a slim profile. Buyers who want a feature display showing real-time GPM and temperatures.
For whom it’s bad
Anyone needing true whole-house coverage in cold climates, or anyone whose panel cannot spare a 60A breaker. Brand-new product lines may have less long-term track record than Rheem or EcoSmart.
8. APUS 14kW — Best for Small Apartments Wanting 3.3 GPM
APUS 14kW Electric Tankless Water Heater, 240V, Up to 3.3 GPM, 3s Instant
14kW at 240V
3.3 GPM max
99.8% efficiency
2-year warranty
Pros
- Up to 3.3 GPM supports 1-2 simultaneous hot water uses
- 99.8% thermal efficiency with self-modulating control
- Compact 11.42 x 13.7 x 3.54 inch wall-mount design
- 2-year manufacturer warranty with 24/7 customer service
Cons
- Some users report actual temperature lower than advertised maximum
- May not be compatible with all home electrical setups
- Professional installation recommended for safety
The APUS 14kW closes out our list as a strong all-around option for small apartments wanting true 3.3 GPM performance without paying a premium. The water-electricity separation design extends element life, and the 24/7 customer service plus 2-year warranty are notable for the price tier. For a buyer in a warm-to-moderate climate with a 200A panel, this is a low-risk choice.
The self-modulating power control keeps the temperature stable during normal demand. At 3.3 GPM with a 35°F rise, the APUS can run a shower plus a kitchen sink simultaneously in most climates. In colder northern regions where inlet water drops below 50°F, the GPM figure drops noticeably and simultaneous use becomes unrealistic.
Setup requires one dedicated 60-amp double-pole breaker and 6 AWG copper cable. The 12.8-pound wall-mount design is light enough to install on standard studs, and the dimensions (11.42 x 13.7 x 3.54 inches) fit comfortably in most apartment utility closets. The slim profile does not sacrifice the LED display, which shows output temperature and flow in real time.
Some user reports mention the actual maximum temperature coming in below the advertised 131°F in certain conditions. This is not unique to APUS — every electric tankless at this kW loses some peak temperature in cold inlet water. Just plan for the realistic ceiling rather than the marketing maximum, and the unit performs as expected.
For whom it’s good
Small apartment owners with a 200A panel who want 3.3 GPM capability at a moderate price point. Buyers in warm-to-moderate climates who appreciate the 2-year warranty and responsive customer service.
For whom it’s bad
Cold-climate apartments with very low inlet water temperatures, or anyone whose electrical panel cannot accommodate a dedicated 60A circuit. Professional installation adds to total cost.
Apartment-Specific Buying Guide for Electric Tankless Water Heaters
Buying an electric tankless water heater for an apartment means answering four questions before you pick a model. Skip any of them and you risk a unit that does not fit your electrical service, your climate, or your hot water habits. This guide walks through each decision so you land on the right model the first time.
1. Does Your Electrical Panel Support the Unit?
The single biggest deal-breaker for an electric tankless install is panel capacity. A 13 kW unit draws 54 amps at 240V, a 14 kW unit draws 60 amps, and an 8 kW unit draws around 33 amps. Most apartments built before the 1990s have 60-amp to 100-amp panels, which cannot safely add a 50-amp or 60-amp circuit. Newer garden-style apartments and modern condos typically have 150-amp to 200-amp panels with breaker space available.
If your panel cannot handle the load, you have three realistic paths: a 120V point-of-use unit on a dedicated 30-amp or 40-amp circuit, a panel upgrade (often $1,500-$3,000, sometimes impossible for renters), or a smaller 240V unit like the 8 kW EcoSmart that draws closer to 33 amps. Check your panel’s amperage rating on the main breaker label before committing to any 13 or 14 kW model.
2. Point-of-Use vs Whole-Apartment
Point-of-use units (under 8 kW or 120V models) serve a single fixture like a kitchen sink or a remote bathroom. They avoid the panel upgrade problem but cannot run multiple fixtures simultaneously. Whole-apartment electric units (11 kW to 14 kW) serve the whole unit from one central location but require significant electrical capacity.
For renters, point-of-use is usually the only feasible path. For owners willing to invest in the electrical work, whole-apartment electric tankless delivers endless hot water and reclaims the floor space a tank used to occupy. Consider whether you actually need simultaneous shower plus dishwasher performance, or whether sequential use is fine for your household.
3. Climate and Inlet Water Temperature
Cold-climate apartments face a hard reality: a 14 kW unit delivers roughly 3.3 GPM at a 50°F rise (warm inlet), but only about 2.0 GPM at a 70°F rise (cold northern winter). That is the difference between running a shower plus a sink and struggling to keep up with a single shower.
If you live in the northern U.S., Canada, or anywhere with winter inlet temperatures below 50°F, lean toward the highest-kW unit your panel can support. If you live in the southern U.S. or in a building with pre-warmed water, an 8 kW or 11 kW unit will feel far more capable than its rated GPM suggests.
4. Sizing Formula: GPM x Temperature Rise = Required kW
Use this simple calculation to figure out what size unit your apartment actually needs. First, count your simultaneous hot water demand: a shower is about 2.0 GPM, a kitchen sink is 1.5 GPM, a bathroom sink is 0.5 GPM. Add the GPM of the fixtures you expect to run at the same time.
Next, calculate your temperature rise: subtract your typical inlet water temperature from your desired output (usually 110-120°F). In Miami the inlet might be 75°F and the rise is 40°F; in Minneapolis the inlet might be 45°F and the rise is 70°F. Multiply required GPM by temperature rise, then multiply by 0.0035 to get the minimum kW. A 1-bath apartment with a 50°F rise needs roughly 18-21 kW for whole-apartment coverage, which is why most electric tankless recommendations for apartments are point-of-use or single-fixture-first designs.
5. Installation and Maintenance Realities
Most electric tankless installs take a licensed electrician two to four hours and run $300-$800 in labor depending on your panel and wire run. Permits are required in most jurisdictions for new 240V circuits. Skip the permit and you risk voided homeowner’s insurance and problems at resale.
For maintenance, descaling is the big one. If your apartment has hard water (above 7 grains per gallon), plan to descale every 12 to 18 months by circulating white vinegar through the unit for 45 minutes. The copper-element and cast-aluminum-chamber designs hold up better than cheaper stainless chambers, but no electric tankless is immune to scale forever. Budget 30 minutes and a gallon of vinegar annually.
For more whole-home options, see our guide to the best tankless water heaters for homes. If you are weighing electric against gas, our best gas tankless water heaters comparison covers the alternatives. Renters weighing a smaller apartment pick can also check our broader best electric tankless water heaters roundup, and our cabin-focused picks for insight on low-flow point-of-use sizing. For another small-space appliance perspective, our best electric smokers for apartments guide covers renter-friendly appliance choices.
Frequently Asked Questions
Who makes the most reliable electric tankless water heater?
Based on long-term owner reports across Reddit, plumbing forums, and verified purchase reviews, Stiebel Eltron and Rheem are the most consistently reliable electric tankless brands. Rheem RTEX series owners report 3-5 year lifespans with no issues, and Stiebel Eltron Tempra units are widely praised by plumbers for build quality. Newer entrants like EcoSmart, ThermoMate, and SIVUATEK deliver strong performance but with shorter real-world track records.
What type of water heater do most apartments use?
Most apartments still use a 30 to 50 gallon storage tank water heater, either gas or electric, typically located in a closet, basement, or utility room. Electric tankless models are gaining popularity in apartments because they wall-mount, need no venting, and fit where a tank cannot. Renters with restrictions on modifications often use a 120V point-of-use electric tankless at a single sink instead of replacing the central tank.
What is the downside of an electric tankless water heater?
The main downsides of electric tankless water heaters are: high upfront electrical requirements (a 13 kW unit needs 54 amps and a 200A panel), inability to run multiple showers simultaneously in cold climates, no hot water during a power outage, hard-water scale buildup requiring annual descaling, and the long wait for hot water to reach distant fixtures unless you add a recirculation pump.
What size tankless water heater do I need for a one-bedroom apartment?
For a one-bedroom apartment with one bathroom, a 11 kW to 14 kW 240V electric tankless unit is the right size if your panel supports it. This handles a shower plus one sink running simultaneously in moderate climates. For studios or single-sink point-of-use needs, a 4.5 kW to 8 kW 120V or 240V unit is sufficient and far easier on the electrical panel.
Can an electric tankless water heater work without a panel upgrade?
Yes, but only if you choose a 120V point-of-use unit or a small 240V model like an 8 kW EcoSmart ECO 8. These draw 30 to 40 amps on a dedicated circuit that most 100-amp panels can accommodate. A 13 or 14 kW whole-apartment unit typically cannot be added without upgrading from 100-amp to 200-amp service, which costs $1,500-$3,000 and is often impossible for renters.
Do electric tankless water heaters work in cold climates?
Electric tankless water heaters work in cold climates but deliver noticeably less flow as inlet temperature drops. A 14 kW unit that delivers 3.3 GPM at a 50°F rise may drop to 2.0 GPM at a 70°F rise in winter. For cold-climate apartments, choose the highest kW unit your panel supports, focus on a single shower as the primary use case, and accept that simultaneous multi-fixture use will be limited during the coldest months.
Final Verdict: Which Electric Tankless Water Heater Should You Buy for Your Apartment?
After comparing 8 of the best electric tankless water heaters for apartments available right now, the Rheem RTEX-13 earns our top recommendation for most buyers. It pairs 99.8% efficiency with 3.17 GPM in a compact, wall-mountable unit that fits easily in an apartment closet. The field-serviceable copper elements and the 4.4-star average across 1,400-plus verified reviews give it the longest real-world track record of any unit in this roundup.
If your apartment cannot accommodate a 200-amp panel, drop down to the EcoSmart ECO 8 for a single-sink point-of-use install with a lifetime warranty, or the CAMPLUX TE05 if you need a 120V-only solution. For owners of 2-bath apartments in warm climates, the SIVUATEK 14kW and APUS 14kW deliver the best temperature consistency and flow in their tier. Whichever unit you choose, confirm your panel amperage and wire run before you buy, and budget a licensed electrician for the install.