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Availability:
In Stock.
Arrives
Friday, Sep 25
Style: Whole Home, 24 kw
Features
- Get the performance you expect. Choose the right size water heater for your home and verify electrical requirements before installation. When properly sized and professionally installed, Rheem Tankless Electric Water Heaters deliver reliable, on-demand hot water while saving valuable space.
- 24kW model provides up to 5.9 GPM
- Multiple fixture applicatons
- Wiring Requirements (RTEX24): Requires 240V singlephase power, three - 40amp doublepole breakers, three sets of #8 AWG copper conductors with ground, and a recommended minimum 200amp household electrical service panel for proper operation
- Digital thermostatic temperature controls in 1-degree increments ranging from 80F - 140F (26C - 60C)
- Saves Energy - Tankless electric water heaters only heat water when a hot water tap is turned on. By heating water only when needed elimantes energy used to maintain desired water temperature in standard tank water heaters.
- Save Space Without Sacrificing Hot Water - Compact design that frees up valuable floor space, 90% smaller than traditional tank water heaters
- No Venting required to operate, simplifying the installation process compared to a tankless gas water heater
- Warranty: 5-Year Leak, 1-Year Parts
Description
The Professional Classic Tankless Electric RTEX-24 240V is engineered to provide continuous hot water on demand, making it ideal for both single point- of-use and multiple applications, with a remarkable flow rate of 5.9 GPM. Its compact design is up to 93% smaller than traditional electric water heaters, allowing for significant space savings, while its energy-efficient operation eliminates standby heat loss when installed near the point-of-use. See performance guide for average expectations in your region based on ground water temperature and application usage. 3 x 40 AMP Double Pole Breakers Required. 200 AMP Household service recommended. Ensure your home can accomodate the power supply and that enough space is available in your breaker panel for this unit.
Brand: Rheem
Capacity: 5.9 gallons
Power Source: Corded Electric
Product Dimensions: 17.63"W x 18.25"H
Special Feature: LED Display
Power Source: Corded Electric
Special Features: LED Display
Wattage: 24 KW
Voltage: 240 volts
Flow Rate: 5.9 gpm
Maximum Temperature: 140 °F
Heat Output: 24 KW
Efficiency: 99.8% Energy efficient
Maximum Pressure: 150
Mount Type: Wall
Maximum Pressure: 150 psi
Capacity: 5.9 gallons
Item Dimensions W x H: 17.63"W x 18.25"H
Item Weight: 17.8 pounds
Item Depth: 3.5 inches
Color: Gray
Style Name: Whole Home, 24 kw
Brand Name: Rheem
Model Number: RTEX-24
Number of Items: 1
Unit Count: 1 Count
Manufacturer: Rheem
Manufacturer Warranty Description: Limited lifetime warranty
UPC: 020352685397
Global Trade Identification Number: 97
Included Components: Fittings, Aerators
Item Type Name: Water Heater
Manufacturer Part Number: RTEX-24
Material Type: Stainless Steel
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Friday, Sep 25
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.
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Top Amazon Reviews
Style: Whole Home, 24 kw
There are many factors to consider before buying an electric tankless heater. By far the most important -- at least for me -- is whether the ground water temperature in your area is consistently warm enough to give the water heater a chance to succeed. I live in North Central Florida where the groundwater temperature is a rock-solid 72F (~22C) year-round. This is the ideal setup for tankless electrics; if you are far north this heater will likely fall short at the exact worst time, i.e. when it's winter and you could really use a nice, hot shower. I recommend looking closely at the map provided on Rheem's website and product pages to determine if this product is right for you. Second caveat, if you have a natural gas hookup, it is worth researching whether a gas-powered unit would be more efficient and/or less costly. There are considerations beyond this, of course, but those are the key ones that will determine whether you will be a happy camper or have cold water poured on those dreams of long, hot showers. If you're still considering after reading the above, then the short of it is (drumroll) ... I'm very satisfied and fully recommend making the jump to tankless! Here's the long-winded version: There is about 25- to 30-feet of pipe to travel between the water heater and the showerhead in my bathroom, and it takes about 25 seconds (well, 22.93 ... yes, I used a stopwatch) for the shower water to reach max temp. I did not use a stopwatch on my tank heater, but I'd guestimate it takes about 10 seconds longer for the tankless to deliver hot water than the tank unit it replaced. The main benefit, again, is that the tankless will continue to deliver hot water indefinitely while the tank is finite -- so, no more playing beat the clock and if you get in the water and realize you forgot your razor or something. The temperature coming out of the showerhead lines up with the temperature on the digital display for the main shower. There is a slight, but noticeable (I'd say 2F-4F/1C-2C) drop from the maximum temperature for the shower furthest away from the water heater. There is enough overhead that you can crank it a few degrees higher -- just be sure your shower handle can settle on something that won't scald you if you go above the recommended! I can also verify that the throughput on the model I bought (24 kW) is enough to handle two showers running at the same as well as start a load of laundry on hot -- I'm sure it could handle more, but there's not a scenario I can imagine where I would need it to. All in all, the flow is as good or better than the water heater it replaced. The dimensions listed on the product page are accurate. As far as your monthly bill, this hasn't made a significant impact although it may in the future. Here's some data from my most recent utility bill compared to the same month last year. Keep in mind the following figures are the daily averages listed on my bill for the whole home, not just the heater, although it is the only major appliance we have replaced over the past 12 months. April 2025 = 33.90 kWh electric and 0.06 KGA water (whole-home daily average) April 2024 = 31.34 kWh electric and 0.03 KGA water (whole-home daily average) Based on the above info (and the prior two months), it's essentially a wash -- we're using more power but only because we're taking longer showers because we can actually enjoy the heat now rather than worrying whether we're leaving enough water for everyone else! I'm sure that our water usage will level out once the novelty wears off, but that might be a while :) Now for the elephant in the room: Installation. If you can't say right now, with confidence and without any further research, whether you could get away with a DIY install, I'll answer the question for you: No, you can't. The plumbing end of the equation is easy -- the only hard part was ditching the tank unit. Beyond that, all you will need is a few fittings and a little pipe to hook it all up, plus the proper hardware to secure it to the wall. Any homeowner who would be comfortable ripping out a vanity sink/faucet and installing a new one should be able to do this portion themselves. The electrical hookup is another story. First, you will need 200-amp service to make this viable; if you don't, save yourself the headache. Second, depending on the distance between your electrical box and your water heater, you may need to have an auxiliary breaker box installed, as we did. Just as water temperatures vary regionally, so do electrician's rates. In our area we paid $850 to have a licensed electrician and his journeyman knock it out -- it took them about three hours and that includes the cost of the pictured auxiliary box. I would expect that rate to be higher in major metros but hopefully it gives a ballpark for what you can expect to pay beyond the sticker price.
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Reviewed in the United States on May 27, 2025 by 2LiveDrew
Style: Whole Home, 24 kw
I’ve had this over a year now and it’s still working perfectly! I just did my first cleaning and it was very easy to descale/clean ! Plus now I have so much more space in my utility room!
Reviewed in the United States on July 29, 2026 by Cherie Jarvis
Style: Whole Home, 24 kw
works great!
Reviewed in the United States on July 29, 2026 by Raq
Style: Whole Home, 24 kw
I was so excited to get this product - I had read nothing but good reviews, heard great things about the company and was thrilled to get it as a gift for the house for the Holidays. Unfortunately - it is one of the worst products I have ever purchased and I hope I save at least one other human from making the same horrible mistake that my family did. It does not heat water consistently, so while using it there are constant bursts of hot and cold water. Worst of all, it does not heat enough the water for us to be able to take baths anymore, which was the entire reason we got this product in the first place. Customer support was a joke. Because we installed it after Christmas, we missed the return window via Amazon, and the solution from Rheem involves hiring another plumber AGAIN to install something else, which isn't even guaranteed to work. I have never regretted upgrading an appliance more in my life, or buying something. I would give anything to be able to take a bath in my home right now. They should be ashamed to sell this product.
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Reviewed in the United States on February 13, 2024 by J Devi
Style: Whole Home, 24 kw
Good Equipment, installed almost a year ago and my electric bill dropped about 90.00 dollars per month.
Reviewed in the United States on July 27, 2026 by Rafael C.
Style: Whole Home, 24 kw
After using for more than a year. Good temperature for shower and general use. If you want a bath, go with a larger unit if you live in Southern PA or farther North as the ground temperature is a little cool for the unit. Or if you have an inside large holding tank that sits at room temperature say from an old hot water system or boiler then the room temp should make this good for a bath water also. Hope this helps . Cheers.
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Reviewed in the United States on November 9, 2025 by IB Combat Engineer Rtd.
Style: Whole Home, 24 kw
So let me begin this by saying that I purchased this off Amazon warehouse for a discounted price of $171. After tax and shipping it came out to $188. This is drastically lower than the price home Depot or Lowe's would offer of nearly $600 plus tax. So when my water heater went out, and I was looking for a quick fix I searched tankless water heater on Amazon and found this. I recently had installed one of these at a friend's house, they got the largest option for the Rheem tankless water heater. The install at their house did not go well. The first unit that we got I installed, and it did not work. I thought it was something I did and spent hours troubleshooting just to find out that the board on the unit, which was brand new, was bad. So we exchanged and got another one and it installed just fine. Plugged it in and it works That said, I wasn't sure what to expect and was hoping for a better situation this time. And a better situation is what I got. I had no problems installing this unit, it's set up very easily and worked exactly as intended. I could not be happier! It is a small compact unit and it heats very quickly. I will update this when the first bill comes if it is outrageous. But I can't imagine it would be. The system seems to work well, and I'm confident that it will continue to do so.
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Reviewed in the United States on January 30, 2024 by Kyle
Style: Whole Home, 24 kw
This is the fourth tankless we've owned. The first was destroyed in a fire and we still have the other two working at family cabins. First I want to point out some fundamental pros. It is small, the size of a suitcase while a tankked heater needs a lot of space. Secondly as long as you have power you never run out of hot water. With three boys in the house we'd run out of hot water with the tank heater, not so with the tankless. The third pro takes a while to notice,, Less electricity use = smaller bill. My average monthly bill was $120. it was $90 after the tankless was installed. The cons would be that if you lose power you have no hot water, but how often does that happen? Also are you needing hot water at the time IF it happens? Second con is the 24& 27KW units need Three double throw 40 amp breakers. and needs feeding with 8 gauge wire. They are whole house units. No you cannot just wire it on your tank heater line. A tank heater doesn't require "INSTANT" power as it uses lower power most ALL of the time. A tankles uses a lot of power ONLY when you need hot water. Most of the time it is off. I've read the low star ratings and it is fairly obvious that these persons did not do their research or read the manual. One complaint was the water only became warm. The person was using a 6kw unit for his full house. Those units are for low flow point of use. Use the correct sie for the intended usage and need! The last con observation is you will notice that it takes the same amount of time to get hot water out to the faucet as it does with a tank heater. The law of physicials and all.... The bottom line here is DO YOUR DUE DILIGENCE/RESEARCH so there are no surprises. The manufacturers tell you what it does and what you need to make it work. My conclusion is I Recommend this unit. When you get it PROPERLY installed it will work so well you will forget about it.
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Reviewed in the United States on March 12, 2023 by Patrick Everdell