Scheduled resistive heating with active over-temperature protection — the starting point for time-based hot water.
K0 is the entry point into the ACRouter ecosystem. You pair your own ESP32/ESP8266-family host with a DimmerLink phase-cut dimmer and drive a heating element smoothly from 0–100% — on a schedule (for example, only during low-tariff windows). It does not measure grid or solar power, so there is no automatic solar routing yet; when you're ready, add an rbAmp sensing module to unlock the closed-loop modes (the K1 / K2 upgrade path).
What's in the box
- DimmerLink phase-cut dimmer — choose the current rating: 16 A / 24 A / 40 A (≈ 3.7 / 5.5 / 9.2 kW at 230 V, resistive)
- On-TRIAC temperature sensor, large heatsink, and an actively-controlled cooling fan for overheat protection
Not included: ESP32 / ESP32-C2 /ESP8266 host, I2C cabling, enclosure, power supply, and the resistive load are supplied by the user.
Modes unlocked
OFF · MANUAL · BOOST (open-loop — no grid/solar sensing). See Operating Modes and the kit comparison in Overview §1.7.
Fully open source — source code & firmware on GitHub; pre-built binaries for ESP32, C2-HTTP, and C2-MQTT
Key features
- Power-rated DimmerLink phase-cut dimmer, selectable 16 / 24 / 40 A
- Active thermal management — on-TRIAC temperature sensor + large heatsink + fan; guards against overheating under sustained load
- Smooth 0–100% phase-angle control on a dedicated PY32 controller (zero-cross handled in-module)
- Runs on ESP32 or low-cost ESP32-C2
- Drive on a schedule via Home Assistant / MQTT / REST (built-in scheduler coming after v2.0)
- Fully upgradeable — add an rbAmp grid sensor later to unlock automatic solar routing (K1 / K2)
- Open-source firmware and documentation
Who it's for
Homeowners who want simple time-based heating on a cheap tariff, and anyone who wants to start minimal and grow into full solar routing without replacing the dimmer.
What you'll also need
- ESP32 / ESP32-C2 host (not included)
- A 3.3 V supply for the module, I2C cabling, and an enclosure
- An AC-mains resistive load (e.g. water-heater element) and a WiFi network
- A scheduler (Home Assistant / MQTT / REST) until the built-in scheduler ships
Specifications
| Parameter | Value |
|---|---|
| Dimmer | DimmerLink phase-cut (I2C) |
| Current rating (choose) | 16 A / 24 A / 40 A (≈ 3.7 / 5.5 / 9.2 kW @ 230 V, resistive) |
| Thermal management | On-TRIAC temp sensor + large heatsink + active cooling fan |
| Control range | 0–100% (phase-angle) |
| Measurement | None (no rbAmp) |
| Operating modes | OFF, MANUAL, BOOST |
| Host | ESP32 / ESP32-C2 — not included |
| Bus | I2C (DimmerLink reference addr 0x50) |
| Connectivity | WiFi · REST · MQTT / Home Assistant |
| Upgrade path | Add rbAmp → K1 (grid) / K2 (grid + solar) |
| Firmware | Open source (ESP32 & ESP32-C2 builds) |