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Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

(10 customer reviews)

Price: $429.00
Sale Price: $375.98

You Save: $53.02

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

SKU: B01MR7Z39V Categories: , Tag:
Brand Rheem



Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Electric Tankless Water Heater

This water heater offers quick, continuous hot water that is on demand for single point-of-use or multiple applications. Robust copper immersion heating elements with brass top increases durability and are threaded for easy replacement. Digital temperature control allows you to set your temperature in increments of 1°

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater



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10 reviews for Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

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    Grant Miller

    I am so impressed with this water heater!! No clicking relays, just totally silent. Simply hot water at your choice of volume. You choose the temp setting and it takes it from there! We (two of us) have a dishwasher, kitchen sink, laundry sink, bathroom sink, and bathtub, all depending on this little guy, and we never have a shortage! The set temperature lights up when you open the valve somewhere. One thing I will tell you, because a bathtub faucet has no restriction like the sinks or even the shower head, the water flows through this heater faster than it can get the water up to your set temperature (I have it set at 130). I remedied this by turning the hot water valve partway off at the bathtub. This restricts the flow into the bathtub JUST enough to allow the heater to keep up, yet is not slow so as to be inconvenient.

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    So far this thing works great! The water heater itself is very easy to install but if you are attempting this as a DIY project be sure to read the spec sheet on your particular model first. If you’re replacing an existing electric water heater keep in mind that most of these units require more than one 240v power source and multiple 2-pole breakers. If you’re having it professionally installed this can substantially affect the cost.It takes anywhere from 10 to 30 seconds to deliver scalding hot water to both the kitchen and bathroom. I rarely have more than a couple of fixtures running at the same time and the heater is installed on an exterior wall with a 90 degree air temperature so we’ll have to see how it does in the winter and after we add an additional bathroom.

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    R. Rosinski

    I’ve been using this for about 6 months now with positive results. It was very easy to install (Running the cable was probably the hardest part). I would say it heats up just as fast as a “normal” hot water tank, but never runs out of hot water. As for energy savings, I’ve seen a noticeably lower bill, but this could be because my other one was very old and inefficient. I plan on running cleaning solution through it twice a year as I’m on a well with a decent amount of calcium in it. Also, I was worried about capacity as I purchased a smaller one but I ended up lowering the temperature on it to save more energy. I am very pleased with this tankless technology.

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    JW Musser

    This is our second unit and it was just installed yesterday and loving it.For some reason the previous owners of our home installed a second hot water heater in the upstairs bathroom. We replace the hot water heater with a smaller Rheem since there isn’t too much demand on it.For the downstairs I went with this bigger unit because of the higher demand. The temp is set at 125 degrees and I will take it up to 130 when I run the dishwasher – just because. Water comes out hot.I would recommend this unit, and the delivery was fast and efficient.

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    Stacey Hughes

    I am super impressed with this product. We had always had the traditional water heater and when it went out we decided to try. So glad I did. My electric bill has gone down and I have hot water when and where I want and how much I want at anytime.

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    Terrific tankless water heater! Nothing like waking up to no HOT water. Plumber installed this Rheem unit in about 2 hours, which included removal of my old tankless unit and testing. Provides ample hot water for the whole house. Even has a stylist look. We love it!

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    Rachel Wentz

    Get a flow regulator for it. Other than that, it’s absolutely perfect!!!!

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    Darrell G.

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     Very good unit. I can feel the Hot Water in about 1-2 minutes in the farthest bathroom. Great unit for a 2,500 sq ft 4 BDRM 3 BTRM House. When installing be sure to use suggested 8 AWG wire for dual 40 Amp Circuit Breakers. Also make sure to vent/open all of the faucets before powering on the unit. If not you can get a error code on the unit. Lastly the unit will only come on when you use the Hot Water, thus the savings $ on electricity, and the LED sceen that shows the temperature will only come on then. Very satisfied.

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    Amazon Customer

    If you’re using this type of water heater be prepared to do some research and make changes. One size does not fit all water needs. This was our third attempt to accomplish hot water for a studio apartment. Read alot of reviews, returned 2 other water heaters after they failed to provide what their boxes claimed. Lots of time on the phone with tech support only to find out even though their products advertise good solid results based on our region, it was a no go. This product shined above the rest! Easy enough to install (required electrical/plumbing adjusts) and we had to adjust the overall water pressure coming in but it finally worked itself into a great flow of continuous hot water. It’s kind of a science and a process but we made it work. Good luck in your quest for the perfect combination of heat and water. Hope this saves you time and effort!

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    It’s a great product, easy to install, a works perfectly! I just hope we never lose electricity while taking a shower. An instant lose of hot water.

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