Fixing the Endless Battery Problem with Zamel RGT-01

Mateusz Kotlarz -

Problem

I’ve been using five Zamel RGT-01 radiator heads for a while — and they’ve been nothing short of frustrating. The biggest issue? Battery life.

Each head required new batteries roughly every month or two, which was completely unacceptable. Even worse, the heads often lost synchronization with the controller, meaning I had to manually restart them to make them work again.

Sometimes I’d get a low-battery warning, sometimes not — there was no consistency at all. And this wasn’t just one faulty unit — all five heads had the same issues.

On top of that, there was no native Home Assistant integration for the RGT-01. I had to manually modify a community library just to see the last synchronization time and valve position. Between the battery swaps, restarts, and missing data, the whole system felt like a constant battle.

Solution

At first, I thought I could fix things by switching from battery power to 230V AC. Unfortunately, that didn’t help much — the power output was too weak, and the RGT-01 units would still randomly restart or freeze.

So I decided to ditch the RGT-01 heads entirely and go with something simpler and more reliable:

  • 230V 1W thermo-electric actuators, connected to
  • Shelly 1 Mini Gen4 switches.

This setup gave me full on/off control over each radiator.
To make it smart, I configured a Generic Thermostat in Home Assistant. For temperature sensing, I used a Xiaomi Bluetooth Temperature and Humidity Sensor.

Here’s my configuration:

climate:
  - platform: generic_thermostat
    name: Heater
    heater: switch.heater
    target_sensor: sensor.temperature_sensor
    min_temp: 16
    max_temp: 26
    away_temp: 18
    cold_tolerance: 0.3
    hot_tolerance: 0.2
    target_temp_step: 0.5
    precision: 0.1

Now the system works flawlessly — the heater turns on when the temperature drops 0.3°C below the target, and turns off when it rises 0.2°C above it.

Simple, efficient, and finally reliable.

Here’s how it looks in practice 👇

Story

Looking back, this whole thing was more painful than it should’ve been. Constantly swapping batteries every few weeks, restarting heads that lost sync, and explaining to my wife why the heating either stopped completely or turned the apartment into a sauna was exhausting.

Every attempt to fix or optimize the RGT-01 ended in failure — it’s honestly one of the worst smart home products I’ve ever used.

After searching high and low for a ready-made 230V radiator head, I couldn’t find anything suitable. That’s when it clicked — I didn’t need a “smart head” at all. I just needed a simple 230V actuator, controlled by Shelly, and integrated through Home Assistant.

Now everything runs smoothly, temperatures are stable, and best of all — no more battery changes ever again.

Setup Summary

Here’s the complete setup I used:

🧠 Smart control: Home Assistant Generic Thermostat
🔌 Relay module: Shelly 1 Mini Gen4
💧 Thermo-electric actuator: Tech Sterowniki 230V / 1W model (normally closed, M30x1.5 thread)
🌡️ Temperature sensor: Xiaomi Bluetooth Temperature & Humidity Sensor
⚙️ Integration type: On/Off control through Shelly → Home Assistant switch entity
🧩 Automation logic: Generic thermostat in YAML configuration
🕒 Response time: Valve fully opens in ~2–3 minutes, perfectly fine for room heating

✅ Result:
Stable heating, accurate temperature control, and zero battery headaches.