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

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, Small, Gray

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, Small, Gray

Q: 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

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?

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.

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

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Product ID: 724817007

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Details

Brand
Rheem
Color
gray
Wattage
18000 W
Voltage
240 Volts
Maximum Flow Rate
4.4 Gallons

⚡18kW high power output

💧Up to 4.4 GPM flow rate

🌡️±1°F precise digital temp control

Frequently Bought Together

Rheem 18kW 240V Tankless Electric Water Heater, Gray

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Description

🔥 Instant Hot Water, Zero Wait — Elevate Your Everyday Comfort!

POWER THAT ADAPTS - State-of-the-art self-modulation technology dynamically adjusts power to match your hot water demand, maximizing efficiency.
STREAMLINED INSTALLATION - Compact design with easy 3/4" NPT bottom water connection and simple screw replacement makes setup hassle-free.
SPACE SMART ENERGY SAVVY - Tankless design saves space and energy by heating water on demand—never run out of hot water again.
DURABILITY MEETS PERFORMANCE - Copper-dipped dual heating elements provide long-lasting, reliable heat delivery for consistent comfort.
PRECISION AT YOUR FINGERTIPS - External digital control with LED display ensures exact temperature every time, eliminating guesswork.

The Rheem RTEX-18 is a compact, 18kW 240V electric tankless water heater featuring precise digital temperature control with ±1°F accuracy, self-modulating power for efficiency, and durable copper-dipped heating elements. Delivering up to 4.4 gallons per minute, it offers easy installation with a 3/4" NPT water connection, making it an ideal energy-saving upgrade for modern homes.

Specifications

Brand	Rheem
Model Number	RTEX-18
Product Dimensions	36.83 x 36.83 x 46.36 cm; 6.7 kg
Color	gray
Name List for Name Plates	Heater
Voltage	240 Volts
Wattage	18000 W
Included Components	Fitting Aerator
Are Batteries Included	No
Model Year	2016
Item Weight	6.7 Kilograms

Have a Question? See What Others Asked

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

How many 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?

how many breakers and what amp.

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