ECOTINYMACH 110V Tankless Water Heater Electric, 3000W Compact Water Heater Under Sink, Conveniently Convertible Between Fahrenheit and Celsius

Why I installed a 3 kW under-sink heater

I set out to add on-demand hot water to a utility sink in a detached workspace where running a long hot-water line from the main house didn’t make sense. The ECOTINYMACH under-sink heater—110V and rated at 3000W—looked like the right balance of compact size and simple plumbing, with the promise of quick heat right where I needed it. After a few weeks of use, I have a good handle on what it does well, where it struggles, and how to get the most from it.

Installation and setup

Physically, the unit is genuinely compact and easy to mount in a base cabinet. I used the included bracket holes with wall anchors, left clearance for hose bends, and plumbed it with standard 1/2" NPT braided stainless lines and a pair of quarter-turn shutoff valves. If you’re reasonably comfortable with basic plumbing, that part is straightforward: cold in, hot out, purge air, check for leaks.

Electrically, it’s not a plug-in appliance. At 3000W on 110–120V, it draws roughly 27–28 amps at full fire. The documentation calls for a circuit breaker of at least 32A and 2.5 mm² conductors (roughly AWG 13). In North America, that doesn’t map neatly to common sizes. I wired mine on a dedicated 120V, 30A breaker using 10 AWG copper, which is the typical way to handle this load here. If you’re near a sink (and you are), using a GFCI breaker or a GFCI-protected circuit is a smart move, and you should follow your local electrical code. If you don’t routinely pull cable or land breakers, hire a licensed electrician—this is not a device for an existing 15A or 20A outlet.

Two practical tips that made installation smoother:
- Install a low-flow aerator (0.5 gpm) on the sink. This heater’s performance is all about flow rate versus temperature rise; the aerator helps you hit the sweet spot.
- Put a shutoff valve on the unit’s inlet and outlet. It makes purging air and future service painless.

Total time: about an hour including electrical prep I had already run for the project.

Controls and day-to-day use

The interface is as simple as it looks. A digital display shows the set temperature, and you can toggle between Fahrenheit and Celsius. I appreciate the F/C switch because I test in °F but often think in °C for deltas. Setpoint adjustments are quick, and the heater engages with a soft click when flow starts.

“Instant” hot water is always a misnomer—there’s the water sitting in the faucet and lines—but because the unit sits inches from the spout, heat arrives in a second or two. There’s no “tank recovery” delay; it heats as long as you’re running water.

Noise is negligible: a quiet relay click and a faint hum under load. It never became a distraction in the cabinet.

Real-world performance

The key to evaluating a small electric tankless unit is understanding temperature rise at a given flow. With 3000W on tap, here’s what I observed in a climate with moderate incoming water temperatures:

• With 60°F inlet water and a 0.5 gpm aerator, I consistently saw 104–108°F at the tap after 5–8 seconds. Handwashing, rinsing tools, and light cleanup were comfortable.
• Bumping flow up to ~0.9 gpm dropped outlet temperatures into the mid-80s to low-90s, which is tepid for most tasks.
• On a particularly cold morning with 48–50°F inlet water, I had to keep the flow extremely low to break 100°F, and 0.5 gpm yielded high 90s. Usable, but not steamy.

This is exactly what physics predicts. A 3 kW heater can provide a strong temperature rise at low flow, or a small rise at higher flow. If you expect a shower-like flow of truly hot water from a single 120V, 3000W unit, you’ll be disappointed. For an under-sink task station, it’s very workable—provided you keep the faucet’s flow in check.

Temperature stability was solid as long as supply pressure and flow remained constant. On city water, that’s easy. On a pressure-tank well system that cycles, I could induce a few degrees of swing as the pump cut in and out. Not catastrophic, but noticeable. If you’re on a well with variable pressure, install a good pressure regulator and stick with a low-flow aerator.

Build quality and plumbing

The housing is a simple white enclosure that wipes clean and doesn’t hog cabinet space. Connections are standard 1/2" NPT, and I had no trouble getting watertight joints with PTFE tape and a gentle hand. The internal flow switch engaged reliably even at low flows with the 0.5 gpm aerator.

I didn’t see any unusual heat bleed into the cabinet, and the case never got too hot to touch. There’s no tank and no anode to worry about, which simplifies long-term maintenance. If you have hard water, consider a small in-line filter or periodic descaling to keep internals free of mineral buildup.

What it’s great at

• Compact, point-of-use hot water: For a bar sink, shop sink, powder room, or outbuilding where a full hot line isn’t practical, it fills the gap effectively.
• Quick, simple controls: The display is legible, the F/C toggle is convenient, and setpoint changes are immediate.
• Efficient use pattern: It only consumes energy when water flows. For short, intermittent sink use, that’s ideal.

Where it comes up short

• Electrical requirements: You really do need a dedicated high-amperage 120V circuit. That’s a barrier if your panel is full or your run is long. The spec’s 32A breaker guidance doesn’t align with common North American breaker sizes, so plan on a 30A circuit with appropriately sized copper.
• Limited temperature rise: In warm climates or with tempered inlet water, it shines. With cold inlet water, you must limit flow to stay in the comfortable range. That’s not a flaw so much as a reality of 3 kW on 120V.
• Sensitivity to flow and pressure: Small changes at the faucet can translate to noticeable outlet temperature changes. A low-flow aerator and steady supply pressure make a big difference.

Getting the best results

• Use a 0.5 gpm aerator. This single accessory maximizes outlet temperature and stability.
• Open the hot side fully and control temperature with flow rather than mixing in cold. Mixing reduces the temperature the heater “sees,” which can cause hunting.
• Keep plumbing runs short between the heater and faucet to minimize initial cold slug and heat loss.
• If you’re on a well, add a pressure regulator to flatten pressure swings.

Who it’s for

• Homeowners and DIYers who want hot water at a single sink without extending the home’s hot water system.
• Small shops, garages, ADUs, and cabins where electricity is available but space and plumbing are at a premium.
• Light-duty use: handwashing, rinsing, and dish prep at a modest flow.

Who should look elsewhere: anyone expecting to run a shower, a high-flow kitchen faucet at full blast, or to get piping-hot water from very cold inlet temperatures without throttling flow. For those cases, a higher-wattage 240V tankless or a small under-sink storage tank heater will serve you better.

The bottom line

The ECOTINYMACH under-sink heater does exactly what a 3 kW, 110–120V point-of-use unit should: it delivers reliable, on-demand hot water for a single sink in a compact package, as long as you respect its power budget. Installation is approachable on the plumbing side and more involved on the electrical side; plan for a dedicated 30A circuit with appropriately sized wiring and protection.

I recommend this heater for point-of-use sinks where space is tight, inlet water isn’t frigid, and you can control flow with a low-flow aerator. It’s a sensible, efficient fix for handwashing and light cleanup in outbuildings, workshops, and small kitchens. If your water is very cold, your pressure is inconsistent, or you can’t provide a proper dedicated circuit, choose a different solution.