Tankless Water Heater Electric 18kW at 240 Volt, ThermoMate On Demand Instant Hot Water Heater Up to 4.4GMP, Self-Modulating Energy Saving for Residential Indoor Shower, Draw 76Amp
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Availability:
In Stock.
Arrives
Tuesday, Aug 4
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Set name: ET-18kW
Features
- [Instant Unlimited Hot Water] - On demand tankless electric water heater, providing hot water in 3 seconds when you need it and as long as you need, eliminating wait time, never run out of hot water again and No More cold shower. Requires 80Amp breaker (2 Sets of Double-pole 40AMP Breakers)
- [Save Money and Space] - Self-modulating technology regulating the amount of energy required to heat water only when you need it with 99.8% efficient, saving up to 60% on water heating cost comparing to traditional tank water heater. Wall mounted compact size with no water tank, convenient for any spaces, saving floor space and fitting into tight spaces.
- [Easy Installation & Safety Protection] - ETL certified with overheating protection, auto stop heating when detecting no water, quality workmanship for leakage protection
- NOTE - Make sure this water heater is the correct size for your hot water need: 18kW 208 ~ 240V (adjustable) draw max 76amp; Required breaker 2 x Double-POLE 40AMP; Wire gauge 2 x 8AWG; Unit size 17.12" x 13.12" x 3.12"; Water connection 3/4" NPT.
Brand: thermomate
Power Source: 240V Hardwired
Product Dimensions: 13.12"W x 17.12"H
Special Feature: Instant hot water, Leaking free and maintenance free heating element
Color: Gray
Power Source: 240V Hardwired
Special Features: Instant hot water, Leaking free and maintenance free heating element
Wattage: 18 KW
Voltage: 240 Volts (AC)
Flow Rate: 4.4 Gallons Per Minute
Maximum Temperature: 140 Degrees Fahrenheit
Heat Output: 18 Kilowatts
Maximum Pressure: 150 Pound per Square Inch
Mount Type: Wall
Is Electric: Yes
Smart Home Compatibility: Not Smart Home Compatible
Item Dimensions W x H: 13.12"W x 17.12"H
Material Type: Alloy Steel
Brand Name: thermomate
Model Number: ET180
Manufacturer: thermomate
UPC: 750139327591
Manufacture Year: 2024
Manufacturer Part Number: ET180
Included Components: Mount Kit
Item Type Name: tankless water heater
Color: Gray
Style Name: 18kW
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Aug 4
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Set name: ET-18kW
***UPDATE*** Month 1 after installing the unit, my electric bill went from $350 the prior month down to $230 the following month. So this has had clear and immediate cost savings for my electrical usage. Very happy with the results! ---------------------- I wanted to replace my traditional tank water heater with an electric tankless, so I did hours of research and comparing models and options. Finally settled on this unit in the 18KW size to fit my needs. I wanted to the next higher up but my electrical panel and home service capacity made that a risk choice. However, I'm delighted at how well the 18kw model works for my whole home use-case. Thankfully due to having an EV, I already had a conveniently located sub-panel installed. All I had to do was upgrade the capacity on that sub-panel, which was as simple as buying a larger breaker and making sure the existing wiring was up to the task. Ended up taking out the old 30amp breaker the tank water heater used out of the main panel, installing a 40-amp dual pole breaker there in its place, then upgraded my sub-panel to 100amps, and finally installing the second 40-amp dual pole breaker in the sub-panel. Ran all the 8 AWG wire to the location where I wanted to mount the water heater and used an appropriate amount of conduit and secured to the wall, which for me thankfully was only about 6 feet of distance. If you have complex electrical situations happening, definitely call in a licensed electrician. At this point it was an easy install to mount the unit on the wall, secure the wiring which was intuitive, and wall labeled. I didn't find any of the wiring or instructions to be wrong or confusing so thats a plus. The moment of truth then arrived, powering on the unit and setting the desired water temperature. A few quick tests and bingo, hot water. Its not been 3 days since the install and multiple showers, laundry, running the dishwasher, etc. No issues whatsoever. In fact, this unit outperforms the tank water heater we had before. My family now reports that they have to set the faucet to a less hot position than they did previous during showers. The water flow is perfect even when both showers are running full blast. We get consistently hot water and don't have to adjust it multiple times during the course of the shower as we did with the old water heater. Overall, very happy with the performance of this unit! My application is a single story, 2 full bath home, so I wanted something that could handle two concurrent showers and the occasional hand washing or laundry running at the same time. And I'm thrilled to say that it works for me better than expected. I also love that its a newer design that separates the heating element from the water flow path, which means less maintenance and easier repairs if something goes wrong in the future. Time will tell in terms of durability, but I was impressed with the quality of the build, its well-made and appears to be a thoughtful and clean design. Other units I checked out before buying this one looked sloppy, not as well designed. I'm so glad I chose this model. Obviously do your research on your electrical capacity, sizing for your use-case, etc. All I can say is that it works for me in my whole house use-case in Central Florida. Northern cold climates may need a more powerful unit. For me, I've got no doubt this will be more efficient and save me money on my monthly electric bill compared to the old unit electrical consumption. To top it all off, I got this on Amazon Prime Day using a deal and the cost was unbeatable for what I got in this unit. Super happy, will update the review in the future should anything else happen to change my mind.
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Reviewed in the United States on October 17, 2023 by Joe
Set name: ET-24kW
So far, i'm liking this unit to its Rheem counter part... I have hard water we joke about it being liquid rock. But this unit so far has been rather nice, performs well, might take a couple seconds longer to warm up, but it gets it nice and hot.. Now its the longevity game i'm gonna see.. Looks like more electronics in this device than the rheem, but maybe they will hold up. Water flow is nice and the installation was pretty normal for the unit, 8 gauge wire etc, just wish it came preslotted for a larger single conduit to make my previous setup compatible, but after trial and error, I got it .... Its a nice small little unit, you can install it anywhere really.. I'd suggest somewhere near but far enough from the breaker panel as the wire is stupid expensive these days.. But if money isn't an issue put it where it works for you.
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Reviewed in the United States on May 12, 2026 by MicahinTN
Set name: ET-14kW
I bought this ThermoMate 14kW 240 VAC tankless water to replace a 50 gallon tank for a friend of the family that had burnt out. We tried replacing the burners, but they kept burning out, too. The wiring itself was questionable (I didn't install the old tank, I just had to try to fix it. I gave up and found this one on Amazon. Mounting was really easy due to its small size. I did have to run new #6 line, get a new StabLok 60A breaker, and create proper drains for the flush. Other than that, this was the easiest tankless install I've ever done. Their house is pretty small, so it produces the perfect amount of hot water for the single mom and disabled daughter. It functions perfectly and has great water flow. She does have a GoFund me to get help funding the replacement of all the wiring, interfaces, and circuit panels in the house. The house was wired back in the 40's, so there are no grounds to any outlets, lights, or electrical devices. She's had several electricians look at the wiring and all agree the home is a fire hazard. Even Idaho Power refuses to help to protect THEIR lines. Please DM me if you would like to help. I'll send you a link or look for "protect-letitias-home-from-fire-hazards".
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Reviewed in the United States on October 6, 2025 Reviewed in the United States on October 6, 2025 by JD Stewart
Set name: ET-3.5kW
Perhaps results vary? I read some decent reviews on this heater. Seemed like decent quality, but it only gets water hot, if you are running it AT A TRICKLE. I don't need hot water coming out like a fire hose, but I need to be able to wash my hands with it. These "cute little water heaters" are just that.... Cute. It is obvious that you are not going to get hot water through one of these at any rate of flow without using a small holding tank, OR 240v. PERIOD. Perhaps my review is not so much at this product but ANY of them in this price range with these specs. Just expecting too much.
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Reviewed in the United States on May 18, 2026 by dave burbage
Set name: ET-18kW
Good quality works very good no issues and easy to install the plumbing. But you do have to add the additional electrical circuits with cut off boxes for each 40 amp line.
Reviewed in the United States on April 11, 2026 by Gamboa
Set name: ET-18kW
I installed this water heater 13 months ago in my daughter’s house. She has a one bathroom home, and it has served well. However, a week ago, the unit stopped heating water. “HH” Is shown on the display. I immediately went online and entered a trouble ticket with Thermomate. The next day I called the customer support number and was encouraged that a person picked up almost immediately. John Is friendly, and did send me a troubleshooting pamphlet. We performed the steps on the pamphlet and let Jon know that did not fix it. After this, the issue got escalated to the support department . As the support department is overseas, I had to wait 24 hours for a reply. However, the ultimate solution was that they are sending me a new hot water heater. So they are honoring their two-year warranty. Easy service to work with, And as I said, the unit was easy to install and has worked fine.
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Reviewed in the United States on July 3, 2024 by Bo Villemain
Set name: ETH-11kW
This tankless water heater has been a great upgrade!! It saves so much space compared to my old one. I’m already noticing the benefits of having instant hot water on demand. Installation was straightforward, the controls are easy to use, and I love the LED display. It feels efficient and modern, and I’m hopeful it will also save on energy costs over time 🙏🏼 Honestly, I wish I had switched to a tankless system sooner. If you’re considering one, this is a fantastic option - both in quality and price!
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Reviewed in the United States on January 30, 2026 Reviewed in the United States on January 30, 2026 by DANAE C.
Set name: ET-3.5kW
Installed this for the kitchen sink and dishwasher. Set at 123 degrees and it's hot in 2 seconds. No issues. Never rings out of hot water.
Reviewed in the United States on April 15, 2026 by Ken from McDonough Ga