Whole house electric tankless
EcoSmart ECOS 18 18kW Specifications
Researched from the DOE test procedures, NFPA 54 and NEC code tables, and manufacturer specifications. Updated .
Quick answer
This page collects what is actually published about the EcoSmart ECOS 18 18kW and shows what those figures produce, computed rather than transcribed. Anything the listing does not publish is not filled in with an estimate.
Published specifications
Everything here is taken from the listing or the manufacturer, and nothing is inferred.
| Specification | Value |
|---|---|
| Kw | 18 |
| Volts | 240 |
Published standard Source: Manufacturer listing data. A specification not listed here is one this listing does not publish. Check the installation manual for the full data plate.
Flow across the temperature rise range
Computed from the published input rating with the energy relation, so these figures cannot disagree with the calculators on this site.
| Temperature rise | Flow | Inlet needed for a 120 F outlet |
|---|---|---|
| 35 F | 3.4 GPM | 85 F |
| 45 F | 2.7 GPM | 75 F |
| 60 F | 2 GPM | 60 F |
| 70 F | 1.7 GPM | 50 F |
| 80 F | 1.5 GPM | 40 F |
| 90 F | 1.3 GPM | 30 F |
Published standard Source: Energy relation applied to the published 18 kW input at 98 percent efficiency. An electric unit converts essentially all its input to heat, so these figures track the manufacturer curve more closely than a gas unit does.
What circuit it needs
At 18 kW and 240 volts this draws 75 amps. NEC 422.13 treats it as a continuous load, so the circuit is sized at 125 percent, giving 46.9 amps of design load split across 2 circuits.
That means 2 breakers of 50 amps and 2 runs of 8 AWG copper. Confirm the circuit count against the installation manual, and see the breaker and wire page for 18 kW, the nearest rating worked through in full.
How it sits against the rest of its category
Other whole house electric tankless in this catalog: EcoSmart ECOS 27 27kW, Bosch Tronic 4000 8.5kW, Bosch Tronic 6100 18kW, Rheem RTEX-13 13kW.
Compare them on input rating and on the figures the manufacturer actually publishes rather than on the headline number in the listing title, which in this category is frequently a maximum measured under conditions the listing never states.
Other whole house electric tankless
EcoSmart ECOS 27 27kW
$549.00The listing states 112.5 amps outright. Treat that as the specification you are buying and the heater as a detail attached to it.
Best for: Only with a service that has the headroom
Check price on Amazon
Bosch Tronic 4000 8.5kW
$229.00A compact 8.5 kilowatt unit from a manufacturer with a service network, which matters more on electric tankless than on almost any other appliance here.
Best for: One fixture, or a point of use upgrade
Check price on Amazon
Bosch Tronic 6100 18kW
$629.00Eighteen kilowatts in the Bosch line. The 6100 is a tankless unit despite the "Tronic" name it shares with the mini tank range, so check the model before ordering.
Best for: A whole house electric install
Check price on AmazonFrequently asked questions
- What are the specifications of the EcoSmart ECOS 18 18kW?
- The listing publishes kw, volts and related figures, shown in full in the table on this page. Anything not shown is something the listing does not publish, and this page does not estimate it.
- What circuit does the EcoSmart ECOS 18 18kW need?
- It draws 75 amps at 240 volts, which becomes 46.9 amps of design load under the NEC continuous load rule. Units this size are split across 2 circuits, each with a 50 amp breaker and 8 AWG copper. Confirm against the installation manual.
- Is this page based on hands-on testing?
- No, and we never claim otherwise. Everything here is compiled from the manufacturer listing, published specifications and the energy relations that turn those specifications into flow and recovery figures. We do not test products in person. Where a figure is not published, this page says so rather than estimating it.
- Are the prices on this page current?
- They come from verified catalog data at the time the page was built, and prices in this category move often. Treat any price shown as a guide and check the listing itself before deciding. Availability moves even faster than price does on water heater accessories in particular.
Turn the breaker off before touching an element. Both legs of a 240 volt circuit are live, so switching one of them off is not enough, and testing with a meter before you touch anything is the habit that matters. Never energise an element that is not submerged: dry firing destroys an element in seconds and can crack the tank lining around it.