Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

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.

I replaced a 55 gallon hot water tank with this unit, I bought a little larger unit than what the ratings said I needed to be safe.Make sure you check your electrical panel to make sure you have room for 3 x 40 double pole 40 amp circuit breakers. I didn’t have enough room, had to add a sub panel plus had to run 9 x 8 gauge wires the unit requires.I’m pretty handy, but asked a certified electrician to help me with the pre wiring. To be honest, I would have been afraid to try and do this myself even with all my experience.Installation was pretty simple after you have the wiring installed. Use 1 inch piping from your electrical panel to the tankless electrical unit or you won’t be able to pull the nine 8 gauge wires through the pipe.I also suggest having an electrical panel with a main breaker so you don’t have to shut the whole house down for the final install.Additionally i installed a surge protector to hopefully protect the unit from power surges which appears to have delicate electronics inside.We’ve only had this unit in operation for 4 days so far, but the water is really hot, have had no issues at this point and I love the added space gained without having the tank.Time will tell if we save 50% on energy, but from all my research it makes sense even with us living in a warm climate.There are several tankless unit manufacturers with great ratings, I went with Rheem because if I have an issue, they are based in the USA and hopefully that means English speaking in my time zone…..Hope my review is helpful to you.

It works very well. It was important to have the correct electrical requirements. We had an electrician connect the unit and we never looked back.

I bought this last August and 8 months later the water gets barely hot enough to take a shower. Can’t get a refund because it’s past 30 days. Can’t get a plumber here to work on it because plumbers hate this. Rheem will not send somebody to fix it. They will just troubleshoot over the phone and send you a part and expect you to find somebody to switch out the part. This product is junk and I would never buy it again.

It takes 60 wats divided into 30 watts separately

Quiet, lots of hot water, very easy to tweak the temperature. I had it installed as part of converting my old house to solar all-electric; so there was a fair amount of electrical and plumbing work needed for this unit.

Very pleased with the product; although, not using it as a stand-alone.It's being used as a water pre-heater for my standard water heater.The water coming into my home (this time of year) is very cold and my regular water heater has difficulty providing a continuous supply of hot water (enjoy taking long, hot showers).With this product as a water pre-heater, my family and I can take showers, run washing machines, and run dishwashers as much as we want and still have plenty of hot water.The unit is very compact given a regular water heater requires quite a bit of space.From an electrical standpoint, it does require ~ 100 amps (220 V).

While remodeling my house, I decided I didn't want to have a big bulky water heater so I did extensive research and chose this one. I have a three bedroom two bath house and I haven't had any problems with this water heater. It's just like a regular water heater, it takes a minute to heat up, but after that it's good to go. I think it actually improved my water pressure as well. I haven't had any issues with it so far and we've been using it for about 2 months. It will stay hot if you are taking a shower and the washer is running or the dishwasher. It's also extremely easy to adjust the temperature. You just turn the little dial on the front. And it only comes on if you are using hot water. I've already noticed a difference in my electric bill!