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Rheem 18kW 240V Tankless Electric Water Heater

4.3 4.3 out of 5 stars 1,677 ratings

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Heater

Purchase options and add-ons

Brand Rheem
Product Dimensions 14.5"W x 18.25"H
Special Feature LED Display
Color Gray
Wattage 18000 watts
Capacity
18 Gallons
Power Source
ac_dc
Material
Stainless Steel
Item Weight
14.8 Pounds

About this item

  • External digital thermostatic control with LED display (+/1 degree accuracy)
  • Most advanced self-modulation, adjust power to meet hot water demand
  • Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM
  • Simple installation – bottom 3/4 inch NPT water connections
  • Threaded for easy replacement, simple installation, digital temperature display
See more product details

Customer ratings by feature

Energy efficiency
4.0 4.0
Easy to install
4.0 4.0
Temperature Control
3.9 3.9
Value for money
3.6 3.6

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Ships from and sold by Miami Water Heater.
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$49.99
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Rheem 18kW 240V Tankless Electric Water Heater
Rheem 18kW 240V Tankless Electric Water Heater
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Price$447.20$299.99$299.99$469.99-7% $279.99
List:$299.99
$239.99
Delivery
Get it Mar 27 - 29
Get it as soon as Wednesday, Mar 27
Get it as soon as Wednesday, Mar 27
Get it as soon as Wednesday, Mar 27
Get it as soon as Wednesday, Mar 27
Get it as soon as Wednesday, Mar 27
Customer Ratings
Energy efficiency
4.0
3.8
4.6
4.0
3.6
4.6
Temperature Control
3.9
3.9
4.4
4.0
4.7
4.6
Tech Support
3.2
3.5
4.1
3.8
3.2
3.6
Easy to install
4.0
3.9
4.4
4.0
4.0
Value for money
3.6
3.6
4.3
3.9
Sold By
Miami Water Heater
Sain Store
ECOTOUCH
THMOS
WINTEMP
yuanroo
capacity
18 gallons
240 gallons
18 kilowatts
13.27 pounds
18 gallons
power source
ac dc
AC
240V/60Hz hardwire
208~240V Hardwire
AC
Corded Electric
mounting type
Wall
Wall
Wall
heat output
18 kilowatts
27 kilowatts
13.8 kilowatts
material
Stainless Steel
Metal, Aluminum, Brass
Acrylonitrile Butadiene Styrene
style
Heater
Indoor Installation
‎Digital
27kW
18 KW
18KW

From the brand


From the manufacturer

Save Energy, water and more with Rheem tankless water heaters
Rheem tankless electric water heaters provide continuous hot water where you need it.

Rheem Tankless Electric Water Heaters

Enjoy continuous hot water so you can do the dishes, wash the laundry, give the pets a bath and still have hot water for a relaxing shower.

Key Benefits

A Rheem tankless heats water only when you need it, so it uses less energy than a tank-type model.

Rheem tankless water heaters save money by using energy only when hot water is needed.

Rheem tankless gas models reduces water waste when the built-in water saving setting is enabled.

Rheem RTEX POU

Saves Energy

Heats water only when you need it, so it uses less energy than a tank-type water heater, making this a sustainable choice.

Saves Money

Compared to a tank-type water heater, you could save up to 50% on water heating costs with point-of-use tankless electric water heaters or up to 34% with whole home models according to the Department of Energy (DOE).

Saves Water

When tankless electric point-of-use water heaters are installed close to where you need hot water, less water is wasted down the drain while waiting on hot water to reach the tap.

Saves Space

Point-of-use Rheem tankless electric models are compact, allowing them to be installed near a fixture (under a sink, in a bathroom or closet) freeing up valuable storage space in your home. Whole home models can be installed on the wall in a central home location.

Rheem tankless indoor models are powerful, energy efficient, and provide continuous hot water.

Additional Benefits

  • Powerful Performance – Our RTEX 24kW model provides up to 5.9 gallons of hot water per minute (GPM) in warm climates, enough for up to 2 showers and 2 sinks at once. Lower kW models also provide continuous hot water at lower flow rates (from 0.9 to 4.4 (GPM).
  • Energy Smart – RTEX models 8, 11, 18 & 24 utilize energy modulation, so they only use the amount of power required to heat the water you need.
  • On-Demand Hot Water – Point-of-use models, RTEX 4, 6, & 8 are installed near where you need hot water, so you get hot water fast.
  • Optimized Operation – Digital temperature control on the front of each model allows easy set point adjustment (RTEX-04 and RTEX-06 models display outlet temperature only).
  • No Venting - Tankless electric water heaters do not require venting, so they can be installed anywhere inside the home.

Rheem RTEX 3 Rheem RTEX 6 Rheem RTEX 11 Tankless Electric Water Heater Rheem RTEX 13 Tankless Electric Water Heater Rheem RTEX 18 Tankless Electric Water Heater Rheem RTEX 24 Tankless Electric Water Heater
RTEX-04 RTEX-06 RTEX-08 RTEX-11 RTEX-18 RTEX-24
Customer Reviews
3.0 out of 5 stars
155
3.8 out of 5 stars
153
3.9 out of 5 stars
294
4.2 out of 5 stars
275
4.3 out of 5 stars
1,677
4.3 out of 5 stars
672
GPM (Max.) up to 0.9 up to 1.5 up to 1.95 up to 2.68 up to 4.4 up to 5.9
Power Source 120V Electric 220V Electric 240V Electric 240V Electric 240V Electric 240V Electric
Kilowatt (Max.) 3.5 kW 6 kW 8 kW 11 kW 18 kW 24 kW
Fixtures Served (Max.) 1 Sink 2 Sinks 3 Sinks 1 Shower, 2 Sinks 2 Showers 2 Showers, 2 Sinks
Height 5-7/8" 5-7/8" 12-5/8" 12-5/8" 18-1/4" 18-1/4"
Width 10-7/8" 10-7/8" 8-1/4" 8-1/4" 14-1/2" 17-5/8"
Depth 2-3/4" 2-3/4" 3-5/8" 3-5/8" 3-1/2" 3-1/2"
Ship Wt. 4.5 Lbs 4.5 Lbs 7 Lbs 8.5 Lbs 14.78 Lbs 17.8 Lbs
Water Connections 1/2" NPT 1/2" NPT 1/2" NPT 1/2" NPT 3/4" NPT 3/4" NPT
Breakers Required (1 x 30)AMP (1 x 30)AMP (1 x 40)AMP (1 x 50)AMP (2 x 40)AMP (3 x 40)AMP

Product information

Technical Details

Additional Information

Warranty & Support

Amazon.com Return Policy:Amazon.com Voluntary 30-Day Return Guarantee: You can return many items you have purchased within 30 days following delivery of the item to you. Our Voluntary 30-Day Return Guarantee does not affect your legal right of withdrawal in any way. You can find out more about the exceptions and conditions here.
Product Warranty: For warranty information about this product, please click here. [PDF ]

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Rheem 18kW 240V Tankless Electric Water Heater


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Product Description

This tankless electric water heater is ideal for mid-range whole-home applications. This unit is ideal for single shower applications in the Midwest. The Rheem Performance tankless electric water heaters offer a continuous, endless supply of hot water. A lower kilowatt unit can provide hot water on demand for single or multiple point-of-use applications while a higher kilowatt unit could provide hot water for a whole house depending on the inlet ground water temperature. Tankless electric water heaters save space, save energy, save money, and require no venting. The sleek, compact size, 90 percent smaller than a tank, allows you to save space and place the unit wherever you want, including under a sink. Tankless units only draw energy when hot water is flowing, while traditional tanks are constantly drawing energy to keep the water in the tank at the desired temperature. Rheem's self-modulating technology can save Up to 50 percent on your water heating bill.

Product guides and documents

Important information

Wattage

18000 watts

Bulb Voltage

240 volts

Customer reviews

4.3 out of 5 stars
4.3 out of 5
1,677 global ratings

Customers say

Customers like the performance, ease of installation, and size of the water heater. For example, they mention that it works well, takes up very little space, and is a perfect fit for an office space. That said, opinions are mixed on temperature adjustment, quality, and value.

AI-generated from the text of customer reviews

135 customers mention96 positive39 negative

Customers like the performance of the water heater. They mention that it works well, the showers and sinks work great, and the system performs well running the washing machine, dishwasher, and shower. Some say that it's fantastic for a three-person home, amazing, and perfect for their home.

"...This one is doing great and haven’t noticed any significant water temperature fluctuations other than maybe for the first week which I call a break..." Read more

"...It’s been only a few months but the system performs well running the washing machine, dishwasher and shower all running at the same time...." Read more

"...Then the new one brand new out of the box did not work properly then finally fail 1yr and 2 months after purchase...." Read more

"...I had it hooked up now for about 3 months. It works great! It cut my electric bill about 30%. Just as I thought it would. Very happy with it...." Read more

92 customers mention80 positive12 negative

Customers find the installation process of the water heater to be super easy. They mention that it's small, frees up space, and easy to connect. Customers also say that the directions are okay, but following electrical instructions is essential. They say that with a higher power rating, it'll be easier to use hot water at multiple points.

"...to help run wire, and as long as you know what your doing it’s very easy to wire up. DO NOT ATTEMPT IF YOU HAVE NO ELECTRICAL KNOWLEDGE...." Read more

"...It is super easy to install. it is small, frees up space, another bonus. costing half of a tank heater...." Read more

"The family enjoys this addition to the home. It was fairly easy to install...." Read more

"...I love this water heater. I really don’t have any complaints. Super easy to install. Takes up like no space...." Read more

41 customers mention33 positive8 negative

Customers like the size of the water heater. For example, they say it takes up very little space, is compact, and is a perfect fit for an office space. Some mention that the tankless system is plenty big enough for their needs.

"...In addition to heating the water it also takes up much less space than the prior 40-gallon unit it replaced leaving us much greater closet space..." Read more

"...It is super easy to install. it is small, frees up space, another bonus. costing half of a tank heater...." Read more

"...I really don’t have any complaints. Super easy to install. Takes up like no space. No more water tank to explode damaging my basement...." Read more

"...This tank did resolve the space issue, and I now have room in front of my car in the garage that I didn't have before. I am happy about that...." Read more

128 customers mention67 positive61 negative

Customers have mixed opinions about the temperature adjustment of the water heater. Some mention that it provides endless hot water to customers outside shower easily, it makes cold water hot, and holds heat for long periods of time. However, others say that the unit provided is defective, does not heat appropriately, and the water temperature fluctuates from hot to lukewarm when they're in the shower.

"...But after the first 4-7 days of usage it leveled out and a hot shower stays hot no matter how long or short it is...." Read more

"...if I have 2 items running at a time (shower and sink) the shower looses all hot water and it goes the sink...." Read more

"...for this model you need 2x40amp breakersthe water is instantly hot, it easily serves 2 showers, one shower+dishwasher and laundry..." Read more

"...No more water tank to explode damaging my basement. It takes longer to get hot water at the furthest end of the house but it’s so worth it...." Read more

56 customers mention21 positive35 negative

Customers are mixed about the quality of the water heater. Some mention it's well-engineered, easy to install and use, and provides a consistent flow of hot water. Others say that it failed three times in that 26 months, and had too many "E-5" error codes that could not be cross referenced.

"...It tripped the breaker thankfully. I contacted the company and they sent me a new wire harness. I replaced it, still the unit wouldn't heat...." Read more

"...We run it at 110 degrees and it keeps up...." Read more

"...It had failed three times in that 26 months, and this was the last straw for me...." Read more

"...tankless has been in my home for over a month and it still trips the circuit breaker...." Read more

29 customers mention18 positive11 negative

Customers have mixed opinions about the value of the water heater. Some mention that it's the best value for the money, and well worth the change. However, others say that it was overpriced, and installation was very expensive.

"...Oh so nice for long baths & showers. Saving money every day not having to constantly beat a tank. Plus the price is great!!" Read more

"...if you can do it yourself... the installation cost is high, as you will have to run new electric and change some plumbing, but that is no biggy...." Read more

"...Husband had no problem with installation. Decent value and works like a charm!" Read more

"...was very tough to install, even by my licensed plumber, but it is well worth it. It works exactly as promised, and is a real energy saver...." Read more

19 customers mention3 positive16 negative

Customers are dissatisfied with the capacity of the water heater. They mention that it can only handle one shower and one sink faucet at once. Some say that the unit cannot run multiple appliances at once, and that it cannot keep up with a single shower.

"...A bigger concern was that this tank can not support two simultaneous showers...." Read more

"...Incandescent bulbs do not flicker- can only handle 1 shower + 1 sink faucet at once...." Read more

"...were 10-15 degrees colder than predicted, at full flow unit was not able to keep up, and produces and E5 error, but reducing shower flow slightly..." Read more

"...You cannot run multiple fixtures at one time because that amount of water flow does not allow the unit to keep up...." Read more

11 customers mention0 positive11 negative

Customers are dissatisfied with the durability of the water heater. They mention that it broke shortly after purchase, and the second heating element fell apart a year later. Some say that the heating element blew up and flooded their office. They also mention that the internal part failed and the weld cracked.

"...Nope, after repressurizing, a weld must have cracked and a slow drip came down the 1st pipe element housing. I thought maybe its not tight enough...." Read more

"...all burned up, with gaping holes, twisted metal, and exposed, broken metal coils. The other element looked perfect...." Read more

"...if it was a manufacturing or handling issue, but some of the sheet metal frame was bent...." Read more

"...One of the prongs was bent over indicating that quality testing was never performed...." Read more

Needs 2 sets of 8/3 wires, with TWO separate 40 amp breakers.
4 Stars
Needs 2 sets of 8/3 wires, with TWO separate 40 amp breakers.
Update:Needs 2 sets of 8/3 wires, with TWO separate 40 amp breakers.Needed to use 1" conduit for all that wire, but hole for wire in the heater is for 3/4" conduit.Can't find a reset button anywhereTech support not open on weekends or holidays.Slow support , but did send new control board after 3rd call.But received over a week later.
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joe
5.0 out of 5 stars Works excellent so far
Reviewed in Canada on August 15, 2022
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12 people found this helpful
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Antonio
5.0 out of 5 stars Buen producto
Reviewed in Mexico on March 19, 2022
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4 people found this helpful
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Enrique
5.0 out of 5 stars Es lo de hoy, fuera gas, fuera depósitos
Reviewed in Mexico on March 14, 2024
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Amazon Customer
5.0 out of 5 stars Awesome, works great!
Reviewed in Canada on April 1, 2022
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jjhv
5.0 out of 5 stars Buen producto
Reviewed in Mexico on December 8, 2023
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