Onsu Home gives you real-time monitoring, scheduling, and temperature control for your internet-connected Rinnai tankless water heater — all from your browser.
Currently supports Rinnai water heaters with Wi-Fi (Control-R compatible). Requires an existing Rinnai Control-R account. More brands planned. Onsu Home is an independent product and is not affiliated with any water heater manufacturer.
Sign In See how it worksTankless water heaters are smart appliances — but their built-in apps often feel like afterthoughts. Onsu Home is a purpose-built web app that puts you in the driver's seat. No app store download needed. Open your browser, sign in, and you're in control.
Set your water temperature from 100°F to 140°F with a beautiful, intuitive dial. See your current setpoint at a glance, with color-coded feedback from cool blue to hot red.
Start your recirculation pump with one tap. Hot water at the faucet in minutes, without wasting gallons waiting for it to arrive. Track your daily usage against your tier limit.
Create recirculation schedules that match your routine. Set the days, time, and temperature — Onsu Home handles the rest. Morning showers. Evening baths. Automatic comfort.
See a detailed timeline of every action: temperature changes, recirculation events, schedule executions, and system status updates. Know exactly what your heater has been doing.
Onsu Home is a progressive web app. Use it on your phone, tablet, or desktop — no app store required. Install it to your home screen for an app-like experience.
Got more than one water heater? Higher tiers let you control multiple devices from a single account. Switch between heaters or manage them all from one dashboard.
Getting started takes about two minutes. No special hardware or technical knowledge required.
Use your existing Google account. No new passwords to remember. Your account is secured through Google's authentication system.
You'll need an existing Rinnai Control-R account — that's the same account you use with the official Rinnai app. If you don't have one, download the Rinnai Control-R app, create an account, and link your water heater first. Then enter those credentials here. Onsu Home connects through Rinnai's cloud API to communicate with your water heater. Your credentials are encrypted at rest and are never sent anywhere except to Rinnai's servers.
That's it. Adjust temperature, start recirculation, create schedules, and monitor your heater — all in real time. The control panel updates as your heater responds.
Want a deeper walkthrough? See the full How It Works guide or check out the FAQ.
Start free. Upgrade when you need more. Every plan includes core monitoring and control.
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Onsu Home currently supports Rinnai water heaters that are Wi-Fi enabled and compatible with the Rinnai Control-R system. You'll need an existing Rinnai Control-R account with your heater already linked before using Onsu Home.
We're working on expanding compatibility to additional water heater brands. If you'd like to be notified when your brand is supported, reach out to hello@thekoshlabs.com.
Onsu Home is an independent product built by The Kosh Labs LLC. It is not affiliated with, endorsed by, or sponsored by any water heater manufacturer. We communicate with your heater through the manufacturer's cloud API.
Onsu Home allows you to adjust your water heater's temperature within the range supported by your hardware. You are responsible for following the safety guidelines published by your water heater manufacturer and your local authorities. The U.S. Consumer Product Safety Commission recommends setting water heaters to no higher than 120°F (49°C) to reduce the risk of scalding. Higher temperatures may be appropriate in some circumstances, but please exercise caution.
We take privacy seriously. Your water heater account credentials are encrypted at rest. Analytics and advertising cookies are only set after you give explicit consent. You can delete all your data at any time from the Account tab. We never sell your personal information.
Read our full Privacy Policy for details on how we handle your data.
Onsu Home is the first product from The Kosh Labs LLC. We build thoughtful tools for everyday life — starting with the things you use most at home.