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.

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Description

🔥 Endless hot water, zero wasted energy ⚡

COMPACT SPACE SAVER - 90% smaller than traditional tanks, fits discreetly under sinks or tight spaces.
ENERGY SMART SELF MODULATION - Automatically adjusts power to match your hot water demand, saving up to 50% on energy bills.
PRECISION TEMPERATURE CONTROL - External LED display with ±1°F accuracy keeps your hot water just right every time.
DURABLE COPPER HEATING ELEMENTS - Field-serviceable dual copper immersion elements ensure long-lasting, reliable performance.
EASY INSTALLATION MAINTENANCE - Threaded 3/4 inch NPT water connections simplify setup and replacement.

The Rheem 18kW 240V Tankless Electric Water Heater delivers continuous hot water on demand with up to 4.4 gallons per minute flow. Featuring a precise digital thermostat with ±1°F 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 modern, space-conscious homes. Durable copper heating elements and easy installation make it a smart, efficient upgrade for single or multi-point hot water needs.

Specifications

Brand	Rheem
Product Dimensions	14.5"W x 18.25"H
Special Feature	LED Display
Color	Gray
Wattage	18000 watts
Voltage	240 Volts
Maximum Flow Rate	4.4 Gallons Per Minute
Maximum Temperature	140 Degrees Fahrenheit
Heat Output	18 Kilowatts
Efficiency	99.8%
Style	Heater
Maximum Operating Pressure	150
Mounting Type	Wall
Is Electric	Yes
Manufacturer	Rheem
Item Depth	18.25 inches
UPC	020352685335
Global Trade Identification Number	00020352685335
Part Number	RTEX-18
Item Weight	14.78 pounds
Item model number	RTEX-18
Is Discontinued By Manufacturer	No
Size	Small
Finish	Stainless Steel
Pattern	Minimalist, Modern
Shape	Rectangle
Installation Method	Wall Mount
Item Package Quantity	1
Water Consumption	7 Gallons
Special Features	LED Display
Usage	Inside; Professional
Included Components	Fittings, Aerators
Batteries Included?	No
Batteries Required?	No

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