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Learn more about financing & leasing here.
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30-day refund / replacement
To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.
To initiate a return, please visit our Returns Center.
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Availability:
Only 1 left in stock, order soon!
Arrives
Sunday, Apr 26
Recently Viewed
Style: 27Kw
Features
- Save up to 50% on your water heating costs
- Save space and reclaim an entire closet worth of storage
- 25-year residential warranty covers all components including heat exchanger
- Patented US design is the only water heater with ultrasonic flow technology
- In-house, expert support is here to answer all your water heating questions
- Advanced, built in diagnostics make troubleshooting easy
- Dry-fire protection prevents elements from burning out
- Straightforward installation with standard 3/4 inch water connections and no venting needed
- Built in LED diagnostics let you monitor system status at a glance
Brand: Optimal
Power Source: ac
Product Dimensions: 14.5"W x 16.5"H
Color: White
Wattage: 27 KW
Brand: Optimal
Product Dimensions: 14.5"W x 16.5"H
Color: White
Wattage: 27 KW
Maximum Flow Rate: 4.5 Gallons Per Minute
Maximum Temperature: 140 Degrees Fahrenheit
Maximum Operating Pressure: 150 Pound per Square Inch
Mounting Type: Wall
Is Electric: Yes
Manufacturer: Its Optimal
Global Trade Identification Number: 43
Item Weight: 18 pounds
Item model number: opti27
Included Components: Tankless Water Heater, Owners Manual, Mounting Template, Mounting Hardware
Batteries Included?: No
Batteries Required?: No
Date First Available: November 4, 2024
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Sunday, Apr 26
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.
- Klarna Financing
- Affirm Pay in 4
- Affirm Financing
- Afterpay Financing
- PayTomorrow Financing
- Financing through Apple Pay
Learn more about financing & leasing here.
Top Amazon Reviews
Style: 12Kw
I love this unit. Quick install, auto restart after electricity goes out, plenty of instant hot water, and common sense programming/interface. The construction, simplistic and genius, is much better than the other hot water heater designs on the market. Holding my breath on the very long warranty. The only item that I’d like to see changed is the space between the cold water intake and the electricity inlet.
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Reviewed in the United States on January 6, 2026 by BT
Style: 27Kw + Wifi
I recently had the pleasure of working with Ryan from Optimal technical department, and I cannot say enough great things about my experience! I was having trouble with the broken part for my tankless water heater, and Ryan went above and beyond to assist me. From the moment I reached out, Ryan was incredibly knowledgeable and patient. He took the time to understand my issue, quickly identified the part I needed, and ensured that I had all the information necessary to make an informed decision. His expertise made the process so much smoother and less stressful. He was able to ship the new part overnight night as well. Not only is the part I received perfect, but my tankless water heater is now functioning flawlessly. I genuinely appreciate Ryan’s dedication to customer service and his commitment to helping me find the right solution. The unit itself is fantastic and has been performing excellently ever since! Thank you, Ryan, for your outstanding support! I would highly recommend Optimal to anyone in need of top-notch customer service and reliable products. Keep up the excellent work!
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Reviewed in the United States on February 16, 2026 by Goran
Style: 27Kw + Wifi
DO NOT BUY THIS HOT WATER HEATER! It was delivered July 8, 2025 and took us 2 or 3 weeks to get it installed. Worked excellent for 2 months and stopped working with electrical error on October 1, 2025. It says error E016, not enough watts and says it has 0 watts yet when the electrician checked it, it has the right amount of watts coming out of breaker box, going into the water heater, and at the heating elements yet it says 0 watts. Husband has tried to call and has sent emails to customer service of Optimal. Customer service has been no assistance thus far. Don’t risk it! The cost for 2 months of use and now cold showers when it was guaranteed for 25 years, just don’t do it!
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Reviewed in the United States on October 28, 2025 by Melissa Davis
Style: 27Kw + Wifi
Its been a few days since install, 27kW plus. I hired an electrician for the three 40 amp service and converting the 30 amp DP breaker to single pole circuit for the new 110 outlet. I installed the heater along with the recirculating pump (Grundfos UP15 - .67 gpm). The house is a large one story and the master bath is at the opposite end of the house from the heater, it took quite a long time for hot water with the old 40 gal tank. Now with the pump on the water at the shower is immediately warm and gets hot much faster. I set the recirc pump to run between 8 am and 9 pm. Tech support answered the first time and walked me through wifi setup, we were unable to connect but promised to send an email for easier wifi setup instructions. If I can get it connected, I have no complaints. Per my electric utility there has been no spike in power usage over the past few days, its actually lower. Update: Tech support contacted me and finished the wifi setup, android app is working now.
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Reviewed in the United States on January 30, 2026 by Fast Fred Fast Fred
Style: 18Kw
What an awesome tankless water heater! One of the coolest features is that it has a flow sensor that determines how much water per minute you are requiring and either increases or decreases the amount of power used to heat the amount of water needed! Basically what that means is that it only uses enough power, and senses it in real time, to heat the water to the temperature desired without using more power than is needed. This among other reasons is why it is a far better solution than any tank water heater on the market and better than most if not all other tankless water heaters available. I have a three bedroom two bathroom house and never run out of hot water even when I I'm taking a shower and remember that I am in the middle of doing a load of laundry. LOL! The amount of money that I save by using this Opti product, coupled with the longer lifespan offered by the product in comparison to the old style tank water heaters and many other competitive product lines, means that this product WILL pay for itself within just a few short years. Additionally, you have to understand that that also means that it will easily save me (far more than) enough money to buy a brand new replacement for it......after the (nearly) unbelievable 25 year warranty expires! Can you imagine how awesome it would be if today's vehicles had anywhere near the quality of the Opti brand, not to mention the unmistakable ROI that the Opti brand offers all those who would simply purchase their product and use it. The biggest thing that I've learned by purchasing and using the Optimal tankless water heater is that it doesn't cost you money to use it - because it, quite literally, pays for itself. It'll only cost you money if you do not upgrade to one of their top quality products. I would give 10 stars for this product if it were possible.
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Reviewed in the United States on August 6, 2025 by Giovanni Armani
Style: 18Kw
When my current home was built, they placed the water heater in the attic. It measures 22" in diameter, but the folding stairs only measure 18" in a 21-inch opening. Every standard electric water heater that I could find measured 22 or more inches in diameter, which of course would leave me with no way to get it into the attic. I hope to install this new on demand water heater within the next few days. What other customers have said in their reviews is true. I had a few questions about this water heater and Ryan was very helpful and kind. I believe that this is a very well thought out and made product, and at age 75, I believe that it will probably outlast me.
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Reviewed in the United States on November 16, 2024 by Steamtrapper49