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opti 27kW 240V 4.5GPM 25-Year Warranty Electric Tankless Water Heater

Ratings & Reviews for Optimal opti 27kW 240V 4.5GPM 25-Year Warranty Electric Tankless Water Heater

4.8
92
Review
 4.8 out of 5
92 Reviews

2 Star
0%

97% Recommend this product

Ratings may include incentivized customer reviews.

What Customers Are Saying

Customers overwhelmingly praise the tankless water heater for delivering endless hot water during simultaneous use—showering while running the dishwasher or laundry without interruption. The compact design frees up valuable space compared to traditional tanks, while the 25-year warranty, energy efficiency, and advanced features like ultrasonic flow sensors and precise temperature control earn strong appreciation. Support team responsiveness and knowledge are frequently highlighted as exceptional. Most find installation straightforward with clear instructions, though some note electrical upgrades are necessary. A few mention a learning curve with tankless operation or initial model-sizing challenges, but these are vastly outweighed by long-term satisfaction and reliability.

Customer review summary generated by AI, including incentivized reviews.
92 Customer Reviews

Efficiency

James came to my house on 9/24 and sold me new windows. He was very helpful and through and today (9/30) Tammy came and measured for my new windows. She said it would probably only be a few weeks before my windows were ready to be installed. Both James and Tammy were very good at their jobs and I am so excited about getting my new windows.

October 1, 2026
Verified Purchaser
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Works great. Easy temperature adjustment.

Would Recommend

Just installed 2 weeks ago. Easy installation and water hook up.

September 26, 2026
From opti 18kW 240V 3.7GPM 25-Year Warranty Electric Tankless Water Heater Verified Purchaser
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Quick Service

Would Recommend

I installed under my kitchen Island counter, and I wasn't getting any hot water, called support and they helped me through some tests (using my voltmeter). narrowed it down to a circuit board and it was shipped next day. It was pretty easy to replace, and I've been very impressed with it so far. Will update after I put it to use for a while.

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Great product for a great price.

Would Recommend

I purchased this for a guest house and was very pleased with the ease of installation and very impressed with the warranty. It provides a great amount of hot water on demand without any wasted energy. A great value for the price.

September 7, 2026
From opti 15kW 240V 3 GPM 25-Year Warranty Electric Tankless Water Heater Verified Purchaser
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Works great!

Would Recommend

We had to replace the control board, it was damaged in transit. It had worked great since the fix.

June 30, 2026
Verified PurchaserIncentivized
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People should know that shopping at Lowe’s is nice

Would Recommend

In the store, I was attended to politely.

June 12, 2026
Verified Purchaser
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Excellent upgrade!!

Would Recommend

Easy to install and the instant hot water. The instructions were clear and complete. The 25 year warranty is a huge plus for this product.

June 9, 2026
Verified PurchaserIncentivized
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Great!

Would Recommend

Excellent service! Ryan was very helpful. They stand behind their product.

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Water is hot

Would Recommend

Easy to install after getting the 40 amps breakers added and the wires ran to it. Simple after that. Temp control works fine.

May 28, 2026
Verified Pro
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Optimal 18

Would Recommend

We bought this after our water heater rusted out. We love the concept of only heating the water as it is used. There is a learning curve when using a tankless water heater or at least there was for us. The water has to run for a few minutes to clear out the cold water in the pipes before the warm water got to the shower. We have a shut off valve on our shower head to cut down on wasted water when washing our hair or soaping our body. When the shower head is cut back on with this tankless he...

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Great Replacement

Would Recommend

I replaced a 20+ year old regular electric water heater with the Optimal 27kW unit. An electrician had to run extra wiring as expected. It took him about 6 hours to install. It works great and has freed up an entire closet area for us. We are very happy with this product.

May 19, 2026
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Efficient size

I like the size

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Would Recommend

I installed one in my duplex and my tennent loves it. Only problem was the extra expense having it installed. It required an upgrade in my electrical panel and rerouting of my water supply lines. I'll never have to worry about leaks from my attic or the extra expense of keeping the water heated.

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Small unit

Would Recommend

We had to get a new hit water after our 10 year old 40 gallon propane unit died. We decided to go with a tankless electric water heater. We chose Opti18 based on both the 25 year warranty and the great reviews. This was super easy to install and has worked flawlessly since. If I had a gripe, it would be having to wait a little more than the 40 gallon unit I previously had. But knowing that I'm not throwing money out the window every time the old unit was heating up helps. So far this was the bes...

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Would Recommend

I haven't installed my tankless water heater yet as I am waiting to receive the free scale inhibitor offered if item is reviewed. However, I am excited about my purchase and if all goes well with the rewiring of my electrical supply, I will be purchasing a second one for the other side of my duplex.

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