EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology

Why I switched to this small tankless unit

I wanted to reclaim space, cut standby losses, and stop timing showers around a half-warm tank. The ECO 11 checked the right boxes on paper: compact, fully electric, self-modulating, and properly sized for a single shower and a couple of sinks in a small space. I installed it in a studio setup and later tried it as a dedicated point-of-use heater for a remote bathroom. In both scenarios, it delivered stable temperatures and genuinely on-demand hot water, with important caveats around climate, electrical service, and flow rates that are worth understanding before you buy.

Setup and installation

Physically, this heater is tiny—about the size of a hardback book (roughly 11.5 x 8 x 3.75 inches). Wall-mounting is straightforward, and the unit can tuck into spaces where a traditional tank would never fit. Electrically, it’s a 240 V, 13 kW appliance that draws up to about 54 amps under full load. That means you need:

• A dedicated 60 A double-pole breaker (follow local code)
• Properly sized copper conductors (6 AWG is typical for this load and distance, but verify for your run length and code)
• A 240 V circuit (not a standard 120 V branch circuit)

If your service panel is a long run from the installation site, budget for heavy-gauge wire—it’s not cheap and it’s not fun to pull. In one of my installs, the short run made the job easy; in another, the wire pull was the biggest part of the project. If you’re not comfortable with high-current circuits, hire a licensed electrician.

Water connections were painless but slightly quirky. The heater’s unions are straight-thread; EcoSmart includes adapter fittings so you can land on threaded pipe or compression depending on your plumbing. If you’re going threaded, use the right sealant and don’t overtighten. I connected to PEX via threaded adapters and had zero leaks. As with any tankless install, place full-port shutoff valves on both sides and add service tees if you want to flush or descale later.

Controls and daily use

Setpoint adjustments are dead simple: a front dial with a clear digital readout. I ran mine at 110–120°F depending on the use case. The self-modulating control reacts quickly; the unit varies power to maintain the set temperature within about a degree. Unlike a tank heater, I rarely mixed in cold at the shower—full hot delivered exactly the temperature I set. If you need a hotter bath fill, bumping the setpoint up for the duration is quick. Once water reaches the fixture (after the usual pipe purge), temperature stays impressively steady.

Noise is minimal. There’s a faint relay click when it activates and a soft electrical hum under high load, but it disappears into normal household sounds.

Performance in real-world conditions

Output on any electric tankless is a function of three variables: incoming water temperature, flow rate, and the unit’s power. In my studio test with municipal water around 68–72°F, the ECO 11 handled:

• A single 2.0 gpm shower comfortably at 110°F
• A shower plus a low-flow hand sink (briefly) without temperature swings
• Bath fills at a slower-than-tank pace unless I raised the setpoint

In cooler inlet conditions, capacity drops. With incoming water near 50°F, expect to run a lower-flow shower head (1.25–1.6 gpm) to maintain a comfortable setpoint, or turn the temperature down a bit. At 40°F inlet, this model becomes best suited to a sink or single low-flow fixture. This is not a flaw—it’s physics. The unit actively reduces flow if necessary to protect your set temperature, which is the right behavior, but you’ll notice a small pressure reduction at high demand in cold seasons.

As a point-of-use heater, it shines. For a distant bathroom or office breakroom, it eliminates the long wait for hot water. In a warm-climate small home, it can serve as a primary heater if you manage simultaneous use.

Energy use and electrical realities

At 13 kW, the heater can draw up to 13,000 W when working hard. That doesn’t mean it runs at full power all the time. The self-modulating control only applies as much power as needed to reach the setpoint given the incoming temperature and flow. Here’s what that looks like in practice:

• A short hand wash might average 3–6 kW for 15–30 seconds.
• A 10–15 minute shower can average anywhere from 5 to 11 kW depending on inlet temperature and flow. That’s roughly 0.8–2.75 kWh per shower.
• Long showers are easy to take with “endless” hot water; if you lean into that, don’t expect miracles on your electric bill. The benefit is eliminating standby losses, not defying thermodynamics.

If you’re on a tight service capacity, be mindful: a 54 A appliance running concurrently with an electric range or EV charging can push your main over its limit. The good news is the heater’s smooth ramp-up and modulation help avoid obvious light dimming, and it’s about as efficient as it gets (near 99% thermal efficiency). The bad news is that the load is real—plan your panel capacity accordingly.

Build quality and serviceability

The enclosure feels solid, with clean internals and labeled connections. The heating elements are field-replaceable, and access is sensible after removing the cover. I like that the unit includes a basic inlet screen to catch debris; I still recommend a proper sediment filter upstream, especially on well water. For hard water, schedule periodic descaling. The small form factor doesn’t complicate service, though you’ll need clearances to remove the cover.

Sizing and expectations

A few hard truths that will make or break your experience:

• Warm climates: The ECO 11 can serve a small home’s hot water if you avoid overlapping heavy uses. It’s best with 65–75°F inlet water.
• Mixed or colder climates: Treat it as a dedicated point-of-use unit (single shower with a low-flow head, or a sink), or step up to a higher-kW model for whole-home coverage.
• Big tubs and rain showers: This isn’t the right model unless you’re comfortable with slower fills or reduced flow.
• Preheat/backup strategies: It pairs nicely as a preheater to a gas tankless or as a backup in a hybrid system. Preheating reduces the gas unit’s load and helps it operate in a higher-efficiency range.

Living with it

Day to day, the experience is refreshingly simple: open the tap, wait for the line to purge, and hot water arrives at the temperature you set. No cycling, no noticeable fluctuations, and no “lukewarm last five minutes.” I appreciated the consistency the most—especially in a shower where a temperature blip is immediately noticeable. For a remote bath, the reduction in wait time and wasted water was significant.

Pros and cons

Pros:
- Compact, neat installation with wall-mount form factor
- Stable, precise outlet temperature thanks to self-modulation
- Eliminates standby losses; near-99% thermal efficiency
- Practical for point-of-use and warm-climate small homes
- Quiet operation and straightforward controls

Cons:
- Requires a 240 V, high-current dedicated circuit (60 A), which may require panel upgrades
- Limited flow in cold inlet conditions; not suitable for high-demand whole-home use in cold climates
- Straight-thread unions with adapters can confuse installers; proper sealing is essential
- Long, indulgent showers will still show up on your power bill

Recommendation

I recommend the ECO 11 for the right use cases: small homes or apartments in warm climates, point-of-use applications (a bathroom, studio, office sink), or as a smart preheater/backup in a hybrid setup. It delivers genuinely stable, on-demand hot water in a compact package with minimal noise and excellent temperature control. Just size it honestly. If your inlet water is cold for much of the year or you want to run a high-flow shower and a second fixture simultaneously, you’ll be happier stepping up to a higher-capacity model. If your electrical panel can handle a dedicated 60 A circuit and your hot water needs align with a 13 kW unit, this heater is an efficient, tidy, and confidence-inspiring choice.