EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology

(10 customer reviews)


Brand EcoSmart
Capacity 2.5 Gallons
Power Source Corded Electric
Item Dimensions LxWxH 3.75 x 17 x 17 inches
Color White

  • The product is highly durable
  • The product is easy to use
  • Manufactured in China
  • Amperage (amps): 75. Activation flow: 0. 3 GPM. Flow Rate @ 35 F Rise (gallons/min): 3. 51 gal (US)/min
  • The product works and is compatible with 2 X 40 AMP (DP) breakers and 2 X 8 AWG wire
  • Lifetime warranty for residential use
  • Save up to 60% on your water heating costs with the most advanced, self modulating technology available
  • Never run out of hot water with an ECOSMART tankless water heater.
  • Save up to 12 cubic feet of storage space.
  • Digital temperature control in 1-degree increments gives users complete control of hot water
  • 75 A



Product Description

This Smart Technology electric tankless water heater is configured as a “whole home” model for climates where incoming water temperature is 62°F and above. The ECO 18 is capable of heating over 2.5 gallons per minute, which is the equivalent of one water saver shower head (with a 1.5 gpm flow) and one sink with a low inlet water temperature of 62°F, and an output setting of 105° F. Two showers emitting no more than 1.5 gpm each can be run simultaneously when incoming water temperature is above 70° F. Digital temperature control allows you to set your temperature in increments of 1°. All tankless water heaters are sized based on flow rate and temperature rise, and there is a direct relationship between the two. So if used in a cold area requiring a high temperature rise, it will be more limited in the amount of fixtures (gallons per minute) it can heat at one time compared to a warmer climate. However, when sized properly it will provide endless hot water and only consume the energy needed, giving the user complete control. Prior to purchase and installation please verify this model is the right size for the expected demand and electrical requirements. The ECO 18 requires a minimum 150 amp electrical panel for installation with (2) 40 amp double pole breakers connected to (2) sets of #8 awg wire. Plumbing connections are 3/4″ NPT. For additional assistance please feel free to contact our support center at 877-474-6473.

From the Manufacturer

This Smart Technology electric tankless water heater is configured for climates where incoming water temperature is 62 Degree F and above. The ECO 18 is capable of heating over 2.5-Gallon per minute, which is the equivalent of one shower head (with a 1.5 gpm flow) and one sink with a low inlet water temperature of 62 Degree F. Two showers can be run simultaneously when incoming water temperature is above 70 Degree F in warmer climates such as South Texas, South Florida, New Mexico, Arizona and South California. These models come with a digital temperature control that allows you to set your temperature in increments of 1 Degree. Prior to purchase and installation please verify this model is the rights size for your hot water needs and electrical requirements.

From the manufacturer

ecosmart, tankless, hot water

Every EcoSmart tankless electric water heater delivers endless hot water, while at the same time saving space, time, money, and allowing you to reduce your overall energy and water use. EcoSmart’spatented, self-modulating, tankless water heating technology can be used worldwide in a variety of applications from homes of any size, business environments such as offices or restaurants, or even recreational vehicles. Each tankless electric water heater is easy to install, dependable, and supported by a knowledgeable customer support team.

Endless Hot Water Ecosmart ECO 11

Save Energy

Save Time

Save Space

Endless Hot Water

When sized correctly your tankless electric water heater will provide you with endless on-demand hot water. It heats water as it passes thru the unit, instead of storing hot water like a traditional tank water heater that can run out of heated water.

Save Energy

EcoSmart features advanced self-modulating technology, only using the amount of energy needed to heat water when you need it.

Save Time

Point-of-use installation and on-demand heating cuts down on waiting for hot water.

Save Space

Traditional tank heaters take up a lot of space, but EcoSmart’ssleek, wall-mounted design frees up floor space for more storage and is 90% smaller than a tank.

ECO 18, tankless electric water heater

ECO 18

EcoSmart ECO 18 is an 18-kilowatt tankless electric water heater ideal for providing hot water for small homes and apartments or larger point-of-use applications. It can provide between 1.8 and 4.3 gallons-per-minute depending on the inlet water temperature. To select the best solution for your hot water needs, please refer to the sizing guide. With EcoSmart you will be happier knowing the warm water you expect is available endlessly, consistently, and on-demand, allowing you to reduce your water and energy waste. Now that feels warm all over! EcoSmart – Sharing the Warmth.

ETL Listed – Electric Testing Laboratories

Tested and certified by the Water Quality Association NSF/ANSI 372 for lead free compliance

ECO 18 sizing, sizing map tankless electric

Important information


18000 watts

Bulb Voltage

240 volts

Additional information

Weight 14 kg
Dimensions 3.75 × 17 × 17 cm



2.5 Gallons

Power Source


Item Dimensions LxWxH

3.75 x 17 x 17 inches




18000 watts


240 Volts

Heat Output

18 Kilowatts


ECO 18

Part Number

ECO 18

Item Weight

14 pounds

Product Dimensions

3.75 x 17 x 17 inches

Country of Origin


Item model number

ECO 18


17 x 14 x 3.5


Water Heater

Item Package Quantity




Included Components

Electric tankless water heater

Batteries Included


Batteries Required


Warranty Description

Lifetime Warranty on electronics exchanger and element. Warranty only covers cost of heater; does not cover labor or any incidental damages.



Domestic Shipping

Item can be shipped within U.S.

International Shipping

This item can be shipped to select countries outside of the U.S. Learn More

Date First Available

October 19 2010



10 reviews for EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology

  1. Bob & Kathy

    What a great buyReplaced our gas tankless with an electric model since we now have plenty of solar panels. We had the space so opted for the 3 breaker unit. Definitely suggest that choice if you have the space. It produces quite a bit more hot water than 2 breaker units. A real surprise is that this unit requires a VERY minimal flow to start heating the water. We definitely recommend this unit to anyone considering an Electric Tankless heater.

  2. Amazon Customer

    Reliable Continuous Hot WaterPurchased this when my traditional water heater went out for a small 2 bedroom 2 bathroom home. Easy to hook up lol for my hubby! I think he took less then 30 min with my daughter as his assistant! It gave us hot showers in the winter and supports two people showering and one person washing dishes at the same time if not more!!

  3. Schrimpieman

    Love the Eco-18 Water Heater! Great Advantages!Installation is fairly straight forward. Included instructions book is very helpful. Keep it for future troubleshooting because there is detailed information within for any faults encountered. I kept the Eco within 5 feet of my main panel to keep the wire runs as short as possible.. I like the design; all connections feed through the bottom and front panel is easy to remove without disturbing wires or plumbing to access inside as needed. LED display remains dormant (off) until unit detects water flow and then pre-set temperature is displayed while water is running. LED display shuts off a few seconds after water flow stops. Using an ordinary kitchen cup, I measured the minimum water flow necessary before heating elements turn on being ABOUT 2 quarts per minute. Heating elements remain dormant unless it detects water flow higher than that approx quantity. Instructions clearly suggest keeping pre-set temperature around 115-120 (F) degrees. FOLLOW this guideline. I experimented with hotter temperatures thinking the quality/consistency of hot water would be better. Actually, having the pre-set too hot is counter-productive because the faucet water will be too hot, you’ll be throttling back to a colder setting at the faucet, and (here we go again) there won’t be enough water flowing through the unit to turn on the heating elements. Then you’ll be constantly adjusting the faucet handle(s) in efforts to get a stable temperature. Keep it at 115-120 and you’ll be quite happy. I live in South Florida and the coldest weather we’ve had this season dropped the incoming cold-water temperature to “only” about 60 degrees on that “cold” morning. So to “stress” the unit, I turned on 2 showers, 2 faucets, full blast, and the washing machine (all at the same time); the ECO 18 had no problem keeping up with the hot-water demand. If your incoming water temps (are lower) and usage quantity (is higher) than my baseline, you’ll have to experiment for yourself or talk with the tech assistance line.Cons? – – Only arbitrarily minimal. My Eco-18 has a pattern of making really hot water, then warm, then hot again as it stabilizes just as the faucet/shower is turned on, only at beginning (eg. Mornings). I verified this by asking a family member to turn on a tub faucet as I measured the temperature at the copper “water-out” side directly near the unit. I can also tell by the way the bathroom lights dim ever so briefly (twice) as the initial electrical surges hit the power panel. After all, the TWO elements pull about 37 Amps EACH at initial start-up. It takes about 7-10 seconds for the unit to stabilize it’s temperature output (and the bathroom lights remain at constant brightness); but I can live with that. It’s no major complaint. If there’s any critics out there: 1.) Yes, I installed all electrical as per NEMA standards, 2.) Yes, my main panel is rated for this amperage with plenty reserve capacity, and 3.) Yes, I installed a separate 100-amp subpanel with two 40-amp breakers dedicated to this water heater (as described in the installation instructions) using (overkill) 6-gauge wire as a safety precaution.Pro’s? – – Small package size, space savings compared to a conventional 40-gallon tank. Hang it on the wall, make the connections, set it once and forget it. “Hot water forever.” On a side note, South Florida water is quite hard. Curiosity got the best of me with the old tank-heater. I cut it open and discovered a 4-inch thick layer of calcium deposits on bottom of 7-year old tank. How does this relate to the Eco-18, you may ask? Well, since water flow through the Eco-18 is at a high velocity, I have a feeling that calcium deposits cannot collect within unit… it will last a looooong time. Time will tell. The one-year duration for my household has proven successful thus far.Middle-Ground Opinions? – – There’s lots of talk about energy cost savings. Well… (?) …I did a comparison of my household’s last year Kilo-Watt usage to this year (month by month) and did not notice any consistent measurable savings. Of course, there are variables to consider such as growing kids, the time they spend in the bathroom preparing for the day, and how much laundry ends up in the hamper every other day. All this tends to increase as teenagers get older. The only quantifiable fact is that the Eco-18 does not consume power while at idle…waiting for the next person to turn on hot water.Despite the lengthy narrative, I’ll give the Eco-18 a number “9” on a scale of 1 to 10. A small human learning curve and adaptation is necessary to live harmoniously with the heater. Be sure to have the temp pre-set to 120, be aware that a minimum water flow is necessary to “wake the heater up”, and don’t be nervous about the lights dimming temporarily as the heating elements energize. …enjoy. 🙂

  4. Jerrod Kowalski

    A few months of ownershipSeems to work as advertised. It’s early to tell home it will work out but it’s easy to adjust and it does the job. It takes a lot of power when it’s in use and little to none otherwise. You need to have a panel that can support it and the volume of water use at hot temps is limited if you have the lower power units. It comes down to how much hot water you will be using at any given time.

  5. WDRM

    Easy installation, so far very pleased!To preface, this is being written by a 30 year old woman, a total girly-girl, though I don’t mind getting my hands a little dirty if it means saving a TON of money. My husband and I did this project in half a day.We just lost a 2 year old tank heater due to our sewer backing up, and we didn’t want to risk another one, since they can’t be used once flooded. We decided on a tankless after reading a lot of reviews. Pricing them locally, they were anywhere from $650 to $2,000 with decent reviews. I found this one on Amazon as well as Sears and a couple other online places with 5 stars on every site. The price fluctuated a lot, but never went over $500. I bought it for $438.This heater is nice and compact. It is 17″ on the longest side, and only weighs 11 pounds. Coming right out of the box, I was impressed with how small it was! The packaging from the factory was good, but one corner mount was a little bent and the plastic knob fell off.We had to build a small wall to mount it on in our 120 year old basement. Just a couple of 2×4’s mounted to the ceiling and it went right up! Mounting it was incredibly easy. I could hold it up with one hand and mark the holes, then leveled it and screwed it right in. The bent corner flattened right out.Using flexible water heater hoses from our local hardware store, I was able to attach the plumbing to the new heater from the old connections in just a couple of minutes. When I first took the covers off the bottom of the heater, a little bit of water leaked out, but after asking around, I’m told that is normal from the pressure testing they do in the factory.Running the electric was the most complicated part of the process. Our main breaker is 150, and though the manufacturer recommends 200, the 150 is sufficient. We were fortunate that our box had plenty of space for the 3 double-pole breakers. The wire required is very thick and heavy, and was a little hard to work with. We ran three lines from the heater to the breaker box.Installing the wire in the heater was simple. The instructions only say to hire a professional electrician. Really, you just run the wires through the bottom, put each one in the electrical panel, connect the ground, and you are done! Connect the breakers, and wallah! You have a water heater!We initially set the temp at 115 degrees, but dropped it down to 110 and it is perfect. It does take a little bit longer for the hot water to reach the shower or sink, but once it does, it stays hot, and stays consistent. Our shower head has a flow rate of 2.5 gpm, and it stayed nice and hot! My husband, son, and I all took hot showers and it was amazing to not have to wait in between!The instructions recommend setting the water heater at the hottest temp preferred for showers, with the idea that you only turn on the hot water and don’t need to mix in cold. This is brilliant!So far we are very, very pleased, and love that we don’t have to worry about a backed up sewer ruining our investment. The project took about 3 hours total with 2 people working on it to install. We were able to do it with all the normal tools we had laying around the house. Our cost for supplies was around $300. It would have been less but my husband cut one of the wires too long, which made the third one too short, so we had to buy an extra $40 25′ wire in addition to the $95 75′ one we initially bought. We needed the following:-wire-3 40amp double-pole breakers-2 conduits for the breaker box-2 flexible water heater hoses-adapters for the hoses from where we had to cut the pipes off the old water heater, primer and glue to connect them-plastic holders to nail the wire to the raftersThat’s it! The wire was the most expensive part after the water heater. The hoses were about $13 a piece, and the rest were just a couple of bucks.I’ll update after we’ve used it for a while!***1 YEAR UPDATE***It’s been a year since we installed our electric tankless water heater, and could not be happier! It does take a little bit longer for the hot water to reach our faucets, but when it does, it is unlimited and stays nice and hot. We can run 4 showers or baths and do a sink full of dishes, all after running a load of laundry, and still have hot water.Our gas and electric bills come as one, and we have not noticed any difference in our bill compared to previous years, switching from a gas tank heater to an electric water heater. I think the fact that we are only heating and using the tank “on demand” vs. having a gas tank that constantly heats, is why.I still recommend this tankless heater to everyone that will listen!

  6. Ryan

    Atlantic Canada ApprovedWorks great for my 1.5 bath home in Atlantic Canada. Longer wait time for hot at my faucets by 15 seconds or so, but it gets nice and hot. I set it to 125F. My utility room is now much colder as I didn’t realize how much heat my old boiler was generating in the room. Hoping to get my power bill with a savings. Installed easy enough. DIY project. I love the space saving, I was able to get another storage shelf into my utility room.

  7. John G. Bergeron

    Unreliable UPDATE Jan 2020Not much to be said. Ordered Early Sept. – Installed Early Oct. Failed a few times. Tech support tries, but seems to not have in dept knowledge. Early Dec. Failed again during coldest weather. Had to fly back from South. Being replaced by different brand for need of reliability. Ecosmart claim 24-7 tech…NOT TRUE – Amazon says “can’t help” missed return window by 2 days….Anyway, seems to have good potential, but don’t be too far away- It simply stops working without rhyme or reason UPDATE Jan 27-2020 replaced by local plumber. electrical consumption reduced by 50%. I had contacted manufacturer numerous times about high electrical consumption

  8. ZenC

    Good Unit, warranty is a joke.We replaced a 60 gallon tank with the 27 Kw unit. It was overkill. In hindsight, half that would have been more than enough. I reduced the water temperature from 135F to 118F and I still have to blend cold water to take a shower. The only difference in performance that is discernible is that it takes a little longer for the water to “get hot” at the faucet. Once hot, it stays that way until shut-off, never getting cold. We’re on city water, mid-September 64F, down to mid 50’s F in winter, and it does the work. A wifi control would be nice to enable remote temperature change.The unit failed on August 10, 2019. I followed the trouble shooting guide on Ecosmart’s web site and was able to easily determine that the impeller in the flow meter had melted. This morning (Monday) I called the companies help line and the technician explained that this is probably due to reverse flow from the heating element. They will ship replacement parts today. He also suggested that I de-scale the unit to help prevent this in the future. Their recommendation is to do this yearly. As we have never had a water tank failure due to scale build-up, i thought that yearly was too pessimistic for our quality of water. To be sure, I also ordered a circulation pump today to de-scale theunit.All to say, excellent service.Now, end of November, after 18 months, one heating element has failed. It is considered a “wear” item. Other manufacturers give a five year component warranty. For the heating element to fail unacceptable. I have buy a new element.

  9. Steve in Victoria

    A great heater.I bought the Ecosmart Eco 27 a month ago to replace a Hubbell 280-3 tankless heater that LITERALLY blew up catastrophically. (You can read more about this below if you are interested).I have to say that this unit is head and shoulders above the Hubbell products in a number of ways and if you are in the market for a tankless heater I’d strongly recommend staying away from Hubbell after my experience.Overall, this unit does a great job in coastal British Columbia where inlet water temperatures in winter are 50 degrees F or below. Unlike the Hubbell unit, it doesn’t struggle to put out 140 degree water with a faucet fully open. The Hubbell never achieved this kind of performance even in the summer months even though it was exactly the same power. Of course, if you open multiple faucets or showers you are likely to see a drop in the temp but most people do not require 140 degree water and should have little problem.The controls on the unit are easy to use but you may need to go to the Ecosmart website to find full instructions as the Owner and Maintenance (O&M) Manual they provide doesn’t describe things like trouble shooting and the various Error messages you can get. But they are on the website.The Eco 27 digital display only lights up when there is a demand for water, and the temperature display can be switched quickly from F to C just by pressing the main rotary temp control knob. Pressing and holding the knob brings up further information including inlet and outlet temp and flow rate. All very easy to access. (Not nearly as easy on the Hubbell)I installed this unit myself and as you can see in the photo had to install an additional electrical sub-panel in order to comply with the need for three separate 40 Amp breakers because my main panel didn’t have enough space to add extra breakers. Not that difficult if you know what you’re doing but it did add about $150 to the cost for the sub-panel, breakers, and cabling. Conveniently, the spacing of the inlet and outlet connections is exactly the same as the Hubbell unit so I only had to do minimal plumbing work. Additionally, the mounting holes are at 16″ centres so it can be mounted to standard wall studs.Lastly but certainly not the final or least great feature of the Eco 27 heater was the price which is about 1/3rd that of the Hubbell 280-3 it replaced. As I mentioned previously, the Hubbell blew up and the price I was quoted to replace JUST the heating chamber on it’s own was DOUBLE the total price of the Eco 27!!So, overall, I’ve been very impressed by this unit.For those interested, my Hubbell 280-3 caused me a number of problems over the years including the fact the the original flow meter was made of a hard plastic compound and when I disassembled the unit in order to replace burned-out heating elements, the threads crumbled and rendered the unit unusable due to leakage. I finally replaced the flow meter with a newer brass-bodied unit (that on it’s own costs about 1/4 of the total price of the Eco 27) but when I turned the unit back on one of the heating elements burned a hole the size of a pea through the side of the heating chamber in what was, literally, a catastrophic explosion. Very fortunately, I was standing right by the heater when this happened and was able to shut off the power and the water otherwise significant damage from flooding or fire could have resulted.What makes this failure most alarming is that, when I contacted Hubbell about it they admitted that they KNEW this could happen but fail to mention it in the O&M manual! I was using the unit 100% in accordance with the manual and yet it still blew up.To make matters worse, once this issue came to light Hubbell completely stopped communicating with me, taking absolutely no responsibility for the fact that their unit can fail catastrophically in normal use. Buyer Beware!!

  10. Glen

    Ok but not for real cold climate amd haven’t noticed much decrease in power billI loved the product but unfortunately due to the rapid declining poor customer service i have decided to cancel my account I habe slways felt that the best customer service I habe ever had was with Amazon but recent transaction has left a horrible scar and I hope nobody else endures this but if you shop here like I did you will soon find out that this once small company that I bive built their trillion dollar company from what I considered the best customer serviced I have ever had now do not need to meet those expectations. Way to go Amazon. Likely this will not get posted because Amazon will want to let people find out the hard way so if not I will find another way to voice my opinion and if it does get posted it just a warning for anyone who has been long time customer

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