A 4.2" e-paper touch display, precision sensor and rechargeable battery — reads the room temperature and drives the right zone in the ZAO ecosystem, without draining the battery and without losing its schedule after a power outage.
Illuminated 4.2" e-paper display (frontlight), capacitive touchscreen with no physical buttons, a precision temperature and humidity sensor, an internal clock with backup battery, and a rechargeable main battery with an integrated charging circuit.
Underfloor heating has high thermal inertia — the screed heats and cools slowly, so the displayed temperature doesn't need to change often. The 4.2" e-paper screen stays permanently visible, with near-zero power draw between refreshes, unlike a classic LCD that keeps draining the battery for hours even while showing the same figure. Interaction is through a capacitive touchscreen, with no physical buttons to jam or wear out.
A high-precision temperature and humidity sensor gives readings accurate enough for real control, not guesswork. An internal clock with a backup battery, separate from the main battery, keeps the per-zone schedule active even through a total power outage — essential for underfloor heating, where resetting the schedule would unbalance the room's temperature for hours because of the screed's thermal inertia.
The ZAO Thermostat for Underfloor Heating Automation runs on an ESP32-C6 with Zigbee 3.0 and pairs natively with Home Assistant through ZHA — no subscription, no mandatory cloud, your data stays on the local network. It's built for zone-by-zone control alongside the rest of the ZAO ecosystem: the Zigbee gateway, the 8-zone control center, and the boiler controller that actually executes the heating command.
PCB design and system architecture done in Romania, built for the local and European market — installers, distributors and end users alike. CE certification in progress: EN 60730 (automatic control devices safety), EN 300 328 (2.4GHz radio) and EN 55014 (electromagnetic compatibility).
The thermostat reads the room temperature and sends the zone command over Zigbee to the ZAO Control Center with 8 zones, which actually switches the thermostatic actuator on the floor manifold. The thermostat is the zone's brain; the control center is the muscle that does the electrical switching.
Underfloor heating has high thermal inertia — temperature cycles are slow, so the screen doesn't need to refresh often. E-paper stays permanently visible, with near-zero power draw between refreshes, unlike LCD which drains the battery constantly even while showing the same value.
The ZAO Thermostat has an internal clock with a backup battery, separate from the main battery. The per-zone schedule stays active even if the thermostat is fully discharged, which matters especially for underfloor heating — a schedule reset would unbalance the room's temperature for hours because of the screed's thermal inertia.
The rechargeable battery, with an integrated charging circuit and full cell protection, provides 2-3 years of autonomy thanks to the e-paper screen's low power draw. It charges over USB-C, with no need to remove the thermostat from the wall.
Want more technical detail? Check the complete underfloor heating thermostat guide.
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