will this supply two showers, washer and dishwasher for two people? (1000 sf house)

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

Paperwork says it requires four 40 amp breakers or two DP 40 amp breakers. Max draw of 75 amps.

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?

Yes you could even go with the unit rtex-15 one smaller if that's it. Good luck

how many breakers and what amp.

The RTEX-18 (240 Volt) requires (2) 40 amp breakers and 8 AWG wire.

Rtex 18 | Desertcart UK

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Description

🔥 Endless hot water, zero waste — upgrade your flow game! 💧

COMPACT SPACE SAVER - 90% smaller than traditional tanks, fits discreetly under sinks or tight spaces for modern living.
EFFORTLESS INSTALLATION - Threaded 3/4 inch NPT water connections make replacement and setup a breeze—no plumber stress needed.
ENERGY SMART SELF MODULATION - Advanced self-modulating tech adjusts power dynamically, saving up to 50% on your water heating bill.
PRECISION TEMPERATURE CONTROL - External digital thermostat with LED display ensures perfect hot water every time with ±1° accuracy.
DURABLE COPPER HEATING ELEMENTS - Field-serviceable dual copper immersion elements guarantee long-lasting, reliable performance.

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 long-term reliability.

Specifications

ASIN	B01MR7Z39V
Best Sellers Rank	#5,960 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #1 in Water Heaters
Brand	Rheem
Brand Name	Rheem
Capacity	18 Gallons
Color	Gray
Customer Reviews	4.2 out of 5 stars 3,981 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	18.25 inches
Item Dimensions W x H	14.5"W x 18.25"H
Item Type Name	Water Heater
Item Weight	14.8 Pounds
Manufacturer	Rheem
Manufacturer Part Number	RTEX-18
Material Type	Stainless Steel
Maximum Pressure	150
Maximum Temperature	140 Degrees Fahrenheit
Model Number	RTEX-18
Mount Type	Wall
Power Source	AC Power
Product Dimensions	14.5"W x 18.25"H
Special Feature	LED Display
Special Features	LED Display
Style Name	Whole Home, 18 kw
UPC	020352685335
Unit Count	1.0 Count
Voltage	240 Volts
Wattage	18000 watts

Reviews

A**R

6.05.2025

E**Y

8.04.2026

K**N

29.03.2026

E**S

20.03.2022

B**R

6.12.2025

2**W

27.05.2025

J**K

30.03.2026

P**E

13.09.2025

D**R

7.01.2026

L**P

2.02.2022

A**A

14.10.2025

A**R

1.04.2022

C**Z

19.03.2021

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Buy anything from 5,000+ international stores. One checkout price. No surprise fees. Join 2M+ shoppers on Desertcart.

£491.47

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In stock

Sold byAmazon UKDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

Buyer Protection · Full refund if your order doesn't arrive as described.

Desertcart purchases this item on your behalf and handles shipping, customs, and support to UK.

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RTEX-18

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