Model # RETE 18

Internet #202514585

Store SKU #452888

Rheem RETE-18 - 18kW 2.73 GPM Tankless Electric Water Heater


RETE-18 - 18kW 2.73 GPM Tankless Electric Water Heater

  • Uses energy only when hot water is needed
  • Compact design allows simple installation almost anywhere
  • Same-day installation in most areas. Call 1-855-400-2552 by noon.
$49800 /each

Frequently Bought Together

Product Overview

The Rheem RETE-18 tankless Electric Water Heater features a rugged brass and copper heater exchanger that is designed to withstand tough water conditions for long life. Its lightweight and compact design enables simple installation in a variety of locations. It is designed to provide hot water for up to two bathrooms in warmer climates or a single bathroom in colder climates. Please click the "More Info" Tab and then "Specifications" to view the Rheem Brochure Guide to assist you in your purchasing decision.

California residents: see   Proposition 65 information

  • Provides a maximum of 3.51 GPM continuous flow at a 35 Degree F temperature rise
  • Designed to provide hot water for up to two bathrooms in warmer climates or a single bathroom in colder climates
  • Flow rate provided by a tankless electric water heater is dependent on the difference in temperature of the incoming cold water supply and the desired hot water delivery temperature
  • 18kW water heater requires a 240-Volt electrical service, 2 separate 40 Amp breaker(s) and 8-Gauge copper wiring
  • Energy efficient, uses hot water only when needed
  • On-unit temperature controls and LED lights indicate active elements and system operation
  • Modulating control adjusts power consumption to meet the required hot water temperature and flow rate
  • Rugged brass and copper heat exchanger is designed to withstand tough water conditions for long life
  • Lightweight and compact design saves space and enables simple installation in a variety of locations
  • Requires 240-Volt electrical connection
  • Equipped with 1/2 in. water connections for easy installation
  • Modulating Control adjusts power consumption to meet the required hot water / temperature flow rate

    How to Choose Your Rheem EcoSense Tankless Electric

    Choose your application, ie. shower, bath tub or vanity sink-faucet, kitchen sink faucet or washer. See chart below.

    For example: you choose a kitchen sink faucet.

    See application chart below and locate your flow rate. For example: your flow rate is 1.5 gpm.

    On the map, locate the average water temperature in your area.

    For example: your water temperature (in Atlanta) is 55°

    Use the water temperature and flow rate chart to determine the model you need.

    For example: 1.5 gpm flow rate + 55° = RETE 9.

  • Click here for more information on Electronic Recycling Programs

Info & Guides

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Warranty / Certifications

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Customer Questions & Answers

will it work with propane?

Asked by: monte
No, this will not work with propane.
Answered by: Rheem
Date published: 2015-11-10

18KW=40Amp x 240V ? How come??

Asked by: CRAZYME
I am a bit unclear of your question. This unit runs three 5500w elements simultaneously using 240 volts to achieve the GPM (gallons per minute) rating. If you have questions or need further clarification please contact our technical support team at 800-431-1549 – 7 to 7central time, 7 days a week, this includes weekends and holidays.
Answered by: Rheem
Date published: 2016-10-24

What size feed and return lines are required?

Asked by: charles
I believe this unit has 1/2" feed and return lines.
Answered by: wfl79
Date published: 2017-03-29

What is the minimum electric service requirement for this unit? How many breakers/amperage needed?

Asked by: Lvtgolf
Amperage is calculated by dividing wattage by voltage So 18,000W / 240V = 75amps Steve
Answered by: Steve
Date published: 2016-07-13
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Customer Reviews

RETE-18 - 18kW 2.73 GPM Tankless Electric Water Heater is rated 3.1 out of 5 by 83.
Rated 2 out of 5 by from I purchased and installed this unit about 5 years ago. I had heard some horror stories from previ... I purchased and installed this unit about 5 years ago. I had heard some horror stories from previous owners at the time, and I placed a filter in front of my water heater. I just found out today that my unit will now require replacement due to two faulty elements according to Rheem Technical Support. I've replaced a few other water heaters in my time, and they usually last longer than 5 years in my environment/area (Florida). I will be replacing my unit with another Rheem, but considered purchasing other brands.
Date published: 2017-03-29
Rated 1 out of 5 by from FLOODED MY HOUSE UNIT BROKE ON. With two 40 amp 220 volt circuits it goes bad real fast... in seconds. In my case the water heater boiled the water and with valves closed it forced pressurized boiling water (250 degrees Fahrenheit) and steam backwards down the main water line. Where the copper pipe meets the white PVC the 3/4 threaded connection blew apart leaving the water main, a 3/4 line, wide open to flood the house. The internal circuit-breakers in the water heater finally switched the unit off. DON'T CALL HD or RHEEM it's a waste of time. Order and new unit online and have it shipped to your house. Swap it out and return the blown unit to HD for full credit.
Date published: 2017-03-23
Rated 4 out of 5 by from This is my second Rete-18 tankless water heater and it has serviced our needs completely. I like ... This is my second Rete-18 tankless water heater and it has serviced our needs completely. I like it when the need for hot water is there without having to wait minutes before it gets hot. I did experience a set back when wiring, the standby light did not come on when wired up. I took the cover off and noticed a wire was not placed where it was needed to be, after it was connected the unit has been working great even though it had been inspected. Going on three months now, working great, hope it lasts at least ten years
Date published: 2017-04-20
Rated 1 out of 5 by from Poor Quality - works for 2 years tops!!! The first one I bought was DOA (red flag) and got this replacement ordered on 6/19/12 at Home Depot in Hurricane, WV. It was installed around August 2012 and it died right after Thanksgiving 2014. So about two years or less is all your going to get out of one of these. I haven't seen where anyone has had one longer than that. So I guess I was lucky. It was in a detached two story garage with a full bath and I bet it didn't have 1000 gallons through it. The board on these are extremely fragile. Remember only 1 year warranty. Should have done my homework before I bought this unit or paid attention to the red flag. Guess I will go back to tank heater. Even the other brands have similar problems.
Date published: 2015-02-05
Rated 1 out of 5 by from Worst product and company ever. change it 3 times and did not last more then YEAR 1/2. then compa... Worst product and company ever. change it 3 times and did not last more then YEAR 1/2. then company wants you to call a service man to come fix it cause they don't cover it. only 1 year warranty. other had broken before the year that's why i had it replace which took an E &P to replace each time. don't wast your money on this product. you will end up spending more and have more frustrations then what you save. costumer service people are rude and not much help at all.
Date published: 2017-03-16
Rated 4 out of 5 by from So Far So Good (maybe I'm lucky) Purchased this unit from HD for use in the renovation of an 800SF Camp in Mid-Coast Maine in 2013. Space is at a premium. Built a new construction 8x10 bathroom with 5' shower, utility sink, stacked front load washer/dryer all within a very small space with a wet wall also serving the kitchen sink. Well water starts out at about 45 degrees. This is a seasonal 8 month camp, so no winter use. Space saving was paramount. Since it was in the new construction area, I was able to have HD wiring laid out in advance so the two 220V 40A circuits in a new 200 Service Panel were not an issue. This is a very hard water area so I designed a 3-stage filtration system, mostly to remove iron and manganese beginning with 1mil sediment, KDF85, and GAC. I also designed the hot water heater to be on a removable panel so I could store the heater in a heated place during winter. This will be my fourth season using this RETE 18. I have to say that I have been very impressed with the On Demand hot water. I take long showers and this unit has never disappointed. I have yet to adjust the shower mixing valve to limit scalding and it could definitely do so as I never shower with full Hot on the valve. The kitchen and utility/vanity sink hot water is the same when washing dishes (no mechanical dishwasher) and the water gets too hot for washing without gloves. I originally set the temp control on medium and have never moved it. So I have tried to limit minerals from the system, I have never set the temp control above medium, and this unit has supplied hot water at about 1.5GPM for "vacation use only", making sure it does not freeze during winter. I have had a small drip that is difficult to stop due to the compression thread input side of the unit. This year I left my heater in VA when driving to ME and had to have it shipped via UPS. I don't think this was an easy trip and - so far - it continues to work. I do not have surge suppression on my Service Panel and worry about frying the circuit board, but since it isn't in service during winter, there is less risk involved. I can see how an electrical spike could take out the unit, as I can with low voltage/current, minerals, and/or too high a temperature setting, and/or expecting too much with long runs and/or too much demand. My main worry about this unit is that my installation is VERY dedicated to this particular unit. I wish it did not use copper compression threads (5/8" I think). It scares me to see all these Reviews (on this and other sites) with all the horor stories. Some thoughts about the reviews: Hard Water, Too High Heat Setting, Improper Wiring, Long Pipe Runs, Long Wire Runs, Improper Wiring Size. Where is the unit installed and what kind of environment is it (wet, hot, cold?). And it would be good to compare it against other brands, costs, and experiences (none of which I have experience with to date). Some thoughts about "Travis" at Rheem: Travis says the same thing and doesn't offer a lot of confidence in Rheem's Warranty or Customer Service. When you are charging $500+ for a product, your QC and CS Response should be better to protect your brand. This bothers me, especially if Rheem changes its design and makes my custom installation difficult to install a different unit. I'm worried about buying a "spare" unit and finding out when I need it, it might be a dud, like so many others have apparently found. As for lights flickering, yes the do WHEN ON. That's a lot of current being drawn, BUT ONLY WHEN THE UNIT IS ON. That's the point, it only draws power when it's on. Think about it: bringing water from 45 to 110 Instantly is a BIG DEAL. We're talking about Thermo Dynamics here. I had a problem with my Frididaire Washing Machine over the 2014 Winter Season. Even after following the Winterizing Instructions, it was so cold that a pipe broke inside the Washer. BUT I HAD BOUGHT A 4-Year Service Contract! Zip Zip, it was covered and fixed Parts and Labor On Site. If Rheem REALLY cared about its Brand and Customer Service - and Quality Control - it should offer a similar Service Contract. Quite often, the cost of Extended Warranties gives the consumer a gauge of the quality of the product. The lower the price for the contract, relative to its purchase price, the more likely the quality is there. Even if there is a QC problem, a Service Contract ends up removing the risk of failure during its life. But I invested $1,200 for the Washer/Dryer and paid about 15% extra for the contract. Service call and parts came out to be about the same $180 I paid for the contract. The RETE18 cost about $450. I'd pay an extra $75 for a contract if it gave me 4 years of warranty service. Looked at another way, my unit has cost me about $150/year so far, and another year of service will bring it to about $100/year - about the cost of one motel room shower for a day. I seldom post Reviews. And I typically take them with a grain of salt, since they are often just a few lines of people who really aren't interested in contributing anything other than their sour grapes. I especially find it annoying when people offer a review that says: "I just got it in the mail today and it came really quick, but I haven't tried it yet." Hopefully my review offers some specifics about my experience over a 3.5 year experience. I'll try to post a picture of my wacky installation that allows me to filter the water and remove the heater from the wall. Too bad it uses compression fittings. I think an earlier reviewer suggesting China could be on to something as the internals don't seem to aligned properly and the threads do seem to leak. Charlie
Date published: 2016-06-12
Rated 5 out of 5 by from Love those long showers! We have a split water system, so when we're so happy with our first tank less waterheater, we decided on a second larger unit for a bath and kitchen. So glad we did. We have a total electric home, so an electric unit was our only choice, but it has been a good one.
Date published: 2017-02-28
Rated 1 out of 5 by from Junk I have went through 4 of them. Longest one lasted 1.5 years then 1 month then 10 mins now we'll see how long this one lasts
Date published: 2016-12-30
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