--- product_id: 273292299 title: "18kW 240V Tankless Electric Water Heater" brand: "rheem" price: "¥291800" currency: JPY in_stock: true reviews_count: 5 category: "Rheem" url: https://www.desertcart.jp/products/273292299-18kw-240v-tankless-electric-water-heater store_origin: JP region: Japan --- # 18kW high power output 4.4 GPM flow rate ±1° LED digital thermostat 18kW 240V Tankless Electric Water Heater **Brand:** rheem **Price:** ¥291800 **Availability:** ✅ In Stock ## Summary > 🔥 Endless hot water, zero wasted energy — upgrade your flow game! ## Quick Answers - **What is this?** 18kW 240V Tankless Electric Water Heater by rheem - **How much does it cost?** ¥291800 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/273292299-18kw-240v-tankless-electric-water-heater) ## Best For - rheem enthusiasts ## Why This Product - Trusted rheem brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Compact Space-Saver:** 90% smaller than traditional tanks, this sleek unit fits effortlessly under sinks or tight spaces—style meets function. - • **Durable & Serviceable:** Copper immersion heating elements built to last and easily field-serviceable for hassle-free maintenance. - • **Effortless Installation:** Threaded 3/4 inch NPT water connections make setup a breeze—get hot water flowing fast without the fuss. - • **Energy-Smart Self-Modulation:** Advanced self-modulating tech dynamically adjusts power to match your hot water demand, slashing energy bills by up to 50%. - • **Precision Temperature Control:** External digital thermostatic control with ultra-accurate LED display ensures your perfect hot water every time. ## Overview The Rheem 18kW 240V Tankless Electric Water Heater delivers continuous hot water on demand with a powerful 18kW output and up to 4.4 gallons per minute flow rate. Featuring a precise LED digital thermostat with ±1° accuracy and advanced self-modulating technology, it optimizes energy use to save up to 50% on heating costs. Its compact, wall-mounted design is 90% smaller than traditional tanks, making it perfect for space-conscious homes. Durable copper heating elements and simple threaded connections ensure easy installation and maintenance, ideal for single shower or whole-home applications. ## 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. Review: Great tankless water heater on demand - Works great was easy to install Review: Very happy with item great quality easy to install - Very happy with purchase , highly recommend. Easy to install and very effective ## Features - 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 ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B01MR7Z39V | | Best Sellers Rank | 336,994 in DIY & Tools ( See Top 100 in DIY & Tools ) 789 in Water Heaters & Parts | | Brand | Rheem | | Capacity | 18 gallons | | Colour | Silver | | Country of Origin | China | | Customer Reviews | 4.2 out of 5 stars 2,061 Reviews | | Efficiency | 99.8% | | Flow Rate | 4.4 Gallons Per Minute | | Global Trade Identification Number | 00020352685335 | | Heat Output | 18 Kilowatts | | Included Components | Fittings, Aerators | | Is Electric | Yes | | Item Depth | 14.5 inches | | Item Dimensions W x H | 36.8W x 46.4H centimetres | | Item Type Name | Water Heater | | Item Weight | 6.7 kg | | Manufacturer | Rheem | | Material | Stainless Steel | | Maximum Pressure | 150 | | Maximum Temperature | 140 Degrees Fahrenheit | | Model Number | RTEX-18 | | Mount Type | Wall | | Part Number | RTEX-18 | | Power source | AC Power | | Product dimensions | 36.8W x 46.4H centimetres | | Special Features | LED Display | | Special feature | LED Display | | Style | Whole Home, 18 kw | | UPC | 020352685335 | | Unit Count | 1.0 count | | Voltage | 240 Volts | | Wattage | 18000 watts | ## Product Details - **Brand:** Rheem - **Capacity:** 18 gallons - **Power source:** AC Power - **Product dimensions:** 36.8W x 46.4H centimetres - **Special feature:** LED Display ## Images ![18kW 240V Tankless Electric Water Heater - Image 1](https://m.media-amazon.com/images/I/91J18WlAKqL.jpg) ## Available Options This product comes in different **Style** options. ## Questions & Answers **Q: will this supply two showers, washer and dishwasher for two people? (1000 sf house)** A: Hello- Sizing an electric tankless is very difficult. I always recommend that you call Rheem at 800-432-8373 to get a suggestion. I want to say this will only keep up with ONLY 1 source of hot water at any one given time. That being said, the RTEX-18 performance ( @240V )- 1.5GPM - 82degree rise 2.0GPM - 62degree rise 2.5GPM - 49degree rise 3.0GPM - 41degree rise So.... what it can keep up with all depends on: -the temp of water coming into the house -the flow rate of each faucet/shower head/washing machine/source of hot water -outlet temp desired I hope this helped :) Ben **Q: How many amps** A: Paperwork says it requires four 40 amp breakers or two DP 40 amp breakers. Max draw of 75 amps. **Q: Rheem rtex-18 be big enough to heat water in my shop to wash my hands and perhaps take a shower in kansas city, mo?** A: Yes you could even go with the unit rtex-15 one smaller if that's it. Good luck **Q: how many breakers and what amp.** A: The RTEX-18 (240 Volt) requires (2) 40 amp breakers and 8 AWG wire. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Great tankless water heater on demand *by R***E on 6 July 2026* Works great was easy to install ### ⭐⭐⭐⭐⭐ Very happy with item great quality easy to install *by A***R on 28 December 2024* Very happy with purchase , highly recommend. Easy to install and very effective ### ⭐⭐⭐⭐⭐ Buen producto *by J***V on 8 December 2023* Bastante cumplidor aun para lo que yo esperaba ya que solo requiero una cantidad relativamente baja de agua caliente y da bastante mas de lo esperado, totalmente recomendable ## Frequently Bought Together - Rheem 18kW 240V Tankless Electric Water Heater, Gray - HYDRO MASTER Tankless Water Heater Service Valve Kit with Pressure Relief Valve 3/4-Inch IPS Isolator Clean Brass - 3/4 Inch IPS Isolator Tankless Water Heater Service Valve Kit with Pressure Relief Valve, Clean Brass, 3/4 Inch Service Installation Valve for rheem,rinai,ecosmart,navien,noritz,takagi,bosch --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.jp/products/273292299-18kw-240v-tankless-electric-water-heater](https://www.desertcart.jp/products/273292299-18kw-240v-tankless-electric-water-heater) --- *Product available on Desertcart Japan* *Store origin: JP* *Last updated: 2026-09-05*