---
product_id: 273292299
title: "Rheem 18kW 240V Tankless Electric Water Heater"
brand: "rheem"
price: "A$1506"
currency: AUD
in_stock: true
reviews_count: 5
category: "Rheem"
url: https://www.desertcart.com.au/products/273292299-rheem-18kw-240v-tankless-electric-water-heater
store_origin: AU
region: Australia
---

# 18kW high power output Up to 4.4 GPM flow rate ±1°C precision digital thermostat Rheem 18kW 240V Tankless Electric Water Heater

**Brand:** rheem
**Price:** A$1506
**Availability:** ✅ In Stock

## Summary

> 🔥 Endless hot water, zero wasted energy ⚡

## Quick Answers

- **What is this?** Rheem 18kW 240V Tankless Electric Water Heater by rheem
- **How much does it cost?** A$1506 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.au](https://www.desertcart.com.au/products/273292299-rheem-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—fits discreetly under sinks or tight spaces for a sleek, modern setup.
- • **Energy-Smart Self-Modulation:** Automatically adjusts power to match your hot water demand, slashing energy waste by up to 50%.
- • **Precision Temperature Control:** External LED display with ±1 degree accuracy keeps your hot water just right, every time.
- • **Durable Copper Heating Elements:** Field-serviceable dual copper immersion elements ensure long-lasting, reliable performance.
- • **Effortless Installation & Replacement:** Threaded 3/4 inch NPT water connections make setup and future upgrades a breeze.

## Overview

The Rheem 18kW 240V Tankless Electric Water Heater delivers continuous hot water with precise digital temperature control and advanced self-modulation technology. Its compact design saves space and energy, providing up to 4.4 gallons per minute flow rate. Durable copper heating elements and easy installation make it ideal for efficient, modern homes seeking reliable, on-demand hot water.

## 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: Hot water on demand - Great product, have been using ours for 2 years and it works great.
Review: Buen producto - 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

## 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 |
| Batteries Required? | No |
| Batteries included? | No |
| Best Sellers Rank | 281,742 in DIY & Tools ( See Top 100 in DIY & Tools ) 914 in Water Heaters & Parts |
| Brand | Rheem |
| Colour | Copper |
| Customer Reviews | 4.2 4.2 out of 5 stars (1,976) |
| Date First Available | 19 Jan. 2017 |
| Energy Efficiency | 99.8% |
| Included Components | Fittings, Aerators |
| Installation Type | Wall Mount |
| Item Weight | 6.7 kg |
| Material Type | Stainless Steel |
| Model | RTEX-18 |
| Part Number | RTEX-18 |
| Product Dimensions | 46.99 x 36.83 x 8.89 cm; 6.7 kg |
| Special Features | LED Display |
| Voltage | 240 Volts |
| Water Consumption | 7 gallons |
| 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

![Rheem 18kW 240V Tankless Electric Water Heater - Image 1](https://m.media-amazon.com/images/I/616uuS+hD9L.jpg)
![Rheem 18kW 240V Tankless Electric Water Heater - Image 2](https://m.media-amazon.com/images/I/71LH0jtHwnL.jpg)
![Rheem 18kW 240V Tankless Electric Water Heater - Image 3](https://m.media-amazon.com/images/I/81+NX7Lb71L.jpg)
![Rheem 18kW 240V Tankless Electric Water Heater - Image 4](https://m.media-amazon.com/images/I/91+--nit2uL.jpg)
![Rheem 18kW 240V Tankless Electric Water Heater - Image 5](https://m.media-amazon.com/images/I/9152Hv+X5cL.jpg)

## 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

### ⭐⭐⭐⭐⭐ Hot water on demand
*by B***K on 10 August 2025*

Great product, have been using ours for 2 years and it works great.

### ⭐⭐⭐⭐⭐ 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

### ⭐⭐⭐⭐⭐ Awesome, works great!
*by A***R on 1 April 2022*

The unit was easy to install and I use the existing hot water tank as a preheat tank. We are on a well and the water is very cold coming up out of the ground, so I set the tank at minimum and it heats the well water to roughly ambient temperature. My gas bill has dropped by 70% and my electric bill has only risen about 3%. This is the only way to go!

## Frequently Bought Together

- Rheem 18kW 240V Tankless Electric Water Heater, Gray
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*Product available on Desertcart Australia*
*Store origin: AU*
*Last updated: 2026-01-24*