We don't ask you to trust us. We show you the math.

METHODThermostatic mix

STANDARDDOE FHR · 70°F ΔT

SIM RATE1 min / 100 ms

LOCATION Enter your ZIP for real local inlet temps · leave blank to use 70°F ΔT default (DOE standard)

ZIP

Region —

Elevation —

Winter inlet —

Summer inlet —

Season

Currently simulating Inlet 55°F Setpoint 125°F ΔT 70°F

SLOT-APrimary Unit EMPTY

SLOT-BHead-to-Head EMPTY

TMLFixture Timeline · 5 AM → 9 PM 0 FIXTURES

Shower 1

Shower 2

Shower 3

Bath

Kitchen

Laundry

↓ Build your day — tap a fixture button below to add your first draw

Tap to add ▸

Each tap places the fixture at a sensible time. Tap a pill on the timeline to remove it.

Speed

DASH-APrimary Unit STANDBY

NOMINAL T+00:00

◂ SELECT UNIT IN SLOT-A ▸

DASH-BHead-to-Head Unit STANDBY

NOMINAL T+00:00

◂ SELECT UNIT IN SLOT-B ▸

SYS · FIRST BOOT · TUTORIAL AVAILABLE

Orientation

Welcome to the stress lab.

This tool simulates real household water demand against A.O. Smith water heaters — with real physics. You can watch a tank run dry in real time, or watch a tankless unit struggle to keep up.

Pick one or two models to test
Load a scenario or build your own
Hit play · watch physics happen
Green → Amber → Red → Mayday

Takes about 60 seconds. You can skip anytime.