Plumbing Picks is reader-supported. As an Amazon Associate, we earn from qualifying purchases at no extra cost to you.
The EcoSmart ECO 11 is rated at 13 kW on 240 V, and its useful flow falls as incoming water gets colder. Start with the fixture you want to supply, your winter inlet temperature and an electrical assessment. The model number alone does not tell you its power or whether it can serve a shower.
Check the EcoSmart ECO 11 on Amazon
Listing checked October 16, 2026. Confirm the exact model and pack size before ordering.
This guide examines the current US product page and linked documents. It is not a hands-on test, reliability score or purchase recommendation. EcoSmart describes the ECO 11 as a point-of-use heater for one or two applications, with shower use conditional on warmer inlet water.
Read flow beside inlet and outlet temperature
EcoSmart’s April 2024 ECO 8/11 specification sheet (files.myrheem.com), page 2, provides the following ECO 11 figures. They assume a 105°F outlet setpoint. They are manufacturer calculations, not measurements from a home installation or ratings at every temperature setting.
| Incoming water | Listed flow |
|---|---|
| 37°F | 1.3 GPM |
| 57°F | 1.9 GPM |
| 77°F | 3.2 GPM |
For example, a hypothetical 2 GPM shower demands more than the chart’s 1.9 GPM at 57°F inlet water. That comparison alone does not approve it for your shower; a higher requested outlet temperature increases the heating task. Add every fixture that may run simultaneously and have the installer size from your coldest expected inlet water.
The linked use-and-care manual (files.myrheem.com), PDF page 8, uses different inlet-temperature steps: 40–80°F, rather than the specification sheet’s 37–77°F. Keep each flow figure with its own temperature and document. Do not combine the rows into a single chart.
The specification sheet lists 0.3 GPM activation. That is the flow needed to trigger heating, not the volume it can heat at any chosen temperature. Self-modulating control adjusts power to demand within the heater’s capacity; it does not remove that limit.
A small cabinet still brings a substantial electrical load
The ECO 11 column specifies 13 kW, 240 V and 54 A. Have a licensed electrician assess the supply voltage, total household load and the exact unit’s installation requirements before ordering. A spare breaker space or the panel’s headline amperage does not establish spare electrical capacity. Do not assume the circuit serving an old storage heater can be reused.
The manual requires qualified electrical and plumbing installation. Treat its wiring diagrams as installer documents. This guide does not provide wiring changes, breaker substitutions or instructions for opening an energized unit. Compare broader systems in our tankless water heater guide.
Allow for connections, service and water conditions
Give the installer the actual location, mounting space and access requirements. The manual describes indoor use, requires protection from freezing and sets conditions for any outdoor protective enclosure. A compact case is not proof of weather resistance or a complete installation footprint.
Plan maintenance around the manual and local water conditions. Its maintenance section calls for annual connection checks and more frequent maintenance with hard water. Ask who will service it and how the installation allows access. Do not translate “tankless” into maintenance-free.
One material detail remains inconsistent: the current product page (ecosmartus.com) lists copper in its heat-exchanger specification, while its performance copy and the April 2024 sheet say stainless steel. Confirm the supplied version with EcoSmart if that material affects your decision. This guide makes no durability claim from either description.
For a single sink, our under-sink heater comparison explains the separate choice between stored hot water and a low-flow tankless unit.
Check registration, installation proof and labor
The linked warranty (files.myrheem.com) heads its mainland USA/Canada coverage as limited lifetime. It requires installation and registration within 30 days of receipt, licensed-installer proof and following its maintenance instructions. It excludes labor charges and specified damage, including scale-related and freezing failures. Read the complete terms for the unit and location.
That document also ends with a five-year reference despite its lifetime heading. Ask EcoSmart to confirm the applicable written coverage before relying on the headline. Budget for installation and service labor separately; the warranty label does not make those costs disappear.