Quick Answer: Renters who can’t do any wiring work should buy a 120-volt plug-in mini-tank — the Bosch Tronic 3000T ES2.5 needs no electrician and no landlord sign-off because it uses a standard outlet. Condo owners or apartment residents who control their own panel and want real whole-unit hot water should look at the EcoSmart ECO 11 (13 kW, 1.3–3.1 GPM), because it runs on a single 60-amp double-pole breaker — the smallest footprint of any whole-unit electric tankless heater. That breaker size matters more in an apartment than a house: NEC 230.79 sets the minimum electrical service disconnect at just 60 amps for multi-family dwellings, versus 100 amps for a single-family home, so an apartment’s entire panel can legally be barely bigger than one tankless heater’s draw.
Most tankless roundups assume you own the building and can run a gas line wherever you want. An apartment changes almost every variable: no outdoor mounting spot, often no gas line at all, a landlord who has to sign off on anything permanent, and — the detail nobody checks first — an electrical panel that code allows to be much smaller than a house’s. This guide sorts picks by what apartment living actually restricts, not by raw GPM.
The panel-size problem nobody mentions
NEC 230.79 splits the minimum service disconnect by dwelling type: 100 amps for a one-family home, but only 60 amps for “all others,” a category that covers most apartment units. A house shopper adding a 13 kW electric tankless heater is adding load to a panel that starts at 100 amps. An apartment resident may be starting from a unit panel that’s legally allowed to be 60 amps for the entire apartment — lights, outlets, HVAC, everything. A 13 kW unit like the EcoSmart ECO 11 pulls roughly 57 amps by itself on its dedicated 60-amp double-pole breaker, which is why it’s sized the way it is: it’s built to be the one large 240-volt load an apartment panel can plausibly carry, not a top-of-the-line whole-home unit like the 36 kW options meant for a house with a 200-amp service.
That’s also why gas gets ruled out for most apartments before flow rate ever comes up. No gas line means no gas tankless heater, full stop, regardless of how good the unit is — and running a new line into a rented or shared-wall unit is a building-approval and insurance question most landlords won’t take on for a single tenant’s preference.
Our top picks at a glance
| Model | Best for | Power | Flow | Install | Price |
|---|---|---|---|---|---|
| EcoSmart ECO 11 | Best whole-unit electric | 13 kW / 240V | 1.3–3.1 GPM | Single 60A double-pole breaker | ~$252 |
| Bosch Tronic 3000T ES2.5 | Best for renters (no wiring) | 1,440W / 120V | 2.5 gal stored | Plug-in, no permission needed | ~$180–210 |
| Stiebel Eltron Mini 3-1 | Best 120V tankless, one fixture | 3.0 kW / 120V / 25A | 0.82 GPM max | Hardwired, 25A breaker | ~$219 |
| EcoSmart ECO 8 | Best for a shared/tight panel | 8 kW / 240V | 1.56 GPM (HD-rated) | 40A double-pole breaker | ~$210–260 |
1. EcoSmart ECO 11 — Best Whole-Unit Electric
EcoSmart ECO 11 Electric Tankless Water Heater
- Draws roughly 57 amps on one dedicated 60-amp double-pole breaker — the smallest footprint of any whole-unit electric tankless heater, matching the same 60-amp figure NEC allows as a multi-family panel's entire minimum service.
- Rated by EcoSmart for a bathroom, small sink, or a single low-flow shower — realistic for a studio or one-bedroom apartment, not a multi-bathroom house.
- 90% smaller footprint than a tank heater and wall-mounts in a closet, per EcoSmart's published dimensions (11.5" × 8" × 3.75").
- Still requires an electrician and landlord approval for the dedicated circuit — this is not a plug-in unit.
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If you own your unit (a condo) or your landlord will approve one dedicated circuit, the ECO 11 is the realistic ceiling for what an apartment-sized panel can absorb. Before buying it, ask your building’s electrician or property manager for the unit’s actual panel size — if it’s genuinely at the 60-amp NEC minimum for multi-family dwellings, a 57-amp draw leaves almost nothing for anything else, and you may need the smaller ECO 8 instead. See our full EcoSmart tankless lineup guide for the complete ECO 8–36 sizing ladder if your building’s service turns out to be larger than expected.
2. Bosch Tronic 3000T ES2.5 — Best for Renters Who Can’t Do Any Wiring
Bosch Tronic 3000T ES2.5 (2.5-Gallon Mini-Tank)
- Plugs into an ordinary 120-volt outlet — no electrician, no dedicated circuit, and no landlord approval needed for wiring in most jurisdictions.
- Mounts on a shelf, wall, or floor, fitting under a bathroom or kitchen sink without touching the building's electrical panel at all.
- Six-year inner-tank warranty, the longest coverage of any option here, which matters if you'll take the unit with you at the end of a lease.
- Won't run a shower — it's a stored-hot-water fix for one sink, not a whole-unit heater.
This is the single lowest-friction option in this guide, and for a renter that friction is the entire point. It requires nothing from a landlord because it adds no permanent load and no new wiring — unplug it and take it with you when the lease ends. It’s a sink fix, not a shower fix, but it solves the single most common apartment complaint (a slow-to-heat or lukewarm bathroom sink) with zero building approval required.
3. Stiebel Eltron Mini 3-1 — Best 120V Tankless for a Single Fixture
Stiebel Eltron Mini 3-1 (3.0 kW Tankless)
- Never runs out the way a mini-tank can — useful for a fixture used continuously rather than in short bursts.
- Needs a dedicated 25-amp breaker, so unlike the Bosch it does require landlord and electrician sign-off before installation.
- Output falls from 0.82 GPM at an 80°F inlet to 0.58 GPM at 70°F, and Stiebel does not recommend it below a 70°F inlet — check your climate before buying.
Choose this over the Bosch only if the fixture sees near-continuous use rather than quick bursts — a bar sink, a salon basin, a lavatory that gets heavy foot traffic. Because it’s hardwired rather than plugged in, it sits in the same permission category as a full whole-unit heater: get landlord approval first, even though the equipment itself is small. Our full point-of-use water heater guide covers the mini-tank-vs-tankless tradeoff in more depth if you’re deciding between this and the ES2.5.
4. EcoSmart ECO 8 — Best for a Shared or Tight Panel
EcoSmart ECO 8 Electric Tankless Water Heater
- Needs only a 40-amp double-pole breaker — meaningfully less headroom demand than the ECO 11's 60 amps, useful if your unit's panel is genuinely near the NEC 60-amp multi-family minimum.
- Sized for a single point-of-use fixture or a light-duty bathroom rather than a full shower in a cold climate.
- No gas line, no venting — same clean electric-only retrofit logic as the ECO 11, just at a smaller scale.
If your building’s electrician says the ECO 11’s 60-amp breaker won’t fit with the unit’s other loads, the ECO 8 is the fallback that still gives you continuous flow rather than stored volume, at roughly two-thirds the amperage. It’s a step down in flow, but for a single point-of-use fixture in a genuinely amp-constrained apartment, it’s often the only whole-unit electric option that actually clears the panel.
How to choose
- Renting, can’t touch any wiring, just want a better sink: the Bosch Tronic 3000T ES2.5 — plug it in, take it with you when you move.
- Renting or owning, want endless flow at one fixture, landlord will approve a breaker: the Stiebel Eltron Mini 3-1.
- Own your unit or landlord approves a dedicated circuit, want real whole-unit hot water: the EcoSmart ECO 11, after confirming your actual panel size.
- Panel confirmed tight, near the 60-amp NEC multi-family minimum: the EcoSmart ECO 8 instead of the ECO 11.
- Unit already has an existing gas line (some condos, duplex-style units): see our best gas tankless water heater guide for a small single-bathroom gas unit instead.
The bottom line
For most apartment renters, the fastest fix that needs zero landlord approval is the Bosch Tronic 3000T ES2.5 — a 120-volt plug-in mini-tank that solves the single most common complaint (a slow bathroom sink) without touching the building’s wiring. For condo owners or renters whose landlord will approve one dedicated circuit, the EcoSmart ECO 11 is the best whole-unit electric option, built around a single 60-amp breaker that respects the same 60-amp minimum NEC allows for an entire multi-family unit’s electrical service. Whichever you pick, check the actual panel size before buying anything 240-volt — in an apartment, that number can be smaller than you’d assume walking in. For the full fuel and sizing comparison once you know your constraints, see our tankless water heater sizing guide and best electric tankless water heater roundup.