Shelly Smart Heating Guide: Relay vs Thermostat – Choose the Best Controller for Your Home

Smart heating is one of the most impactful upgrades you can make to your home – it boosts comfort, saves energy, and gives you control from anywhere. Shelly offers a versatile range of devices that can turn almost any heating system into a smart one. But with multiple approaches available, choosing the right solution can be confusing: should you go for a relay, a thermostat, or a simple smart plug? Each option serves different heating types, home layouts, and budgets.

This buying guide breaks down the two main smart heating control methods using Shelly products: relay-based control for electric heating systems and thermostat-based control for precise temperature regulation. We'll explore the strengths of each, recommend specific Shelly devices, and help you decide which path fits your home. Whether you're heating a single room with a portable heater or managing whole-home electric underfloor heating, there's a Shelly solution ready for you.

Relay-Based Heating Control: Power and Simplicity for Electric Systems

Relays are the workhorses of smart heating, especially for electric systems like baseboard heaters, fan heaters, electric radiators, and in-floor heating. A smart relay acts as a remotely controlled switch: it turns the heating circuit on or off based on a schedule, a temperature reading, or a voice command. Shelly relays are compact, easy to install, and integrate seamlessly with home automation platforms like Home Assistant, Google Home, and Alexa.

For high-power electric heaters, consider the Ogemray Smart relay 25A – it handles up to 25 amps, making it ideal for heavy loads like large electric heaters or multiple radiators on one circuit. If you want energy monitoring alongside control, the Shelly PM Mini Gen3 x2 offers real-time power consumption tracking. This lets you see exactly how much energy your heating uses and adjust schedules to save money. Both devices can be controlled via Wi-Fi, so no hub is required, and they fit behind switches or in electrical boxes.

• Best for: electric baseboard, fan heaters, in-floor heating, and any 230V electric heating circuit.
• Key advantage: direct on/off control with no need for a separate thermostat – you can pair it with temperature sensors for automation.
• Energy monitoring with Shelly PM Mini Gen3 x2 helps you identify waste and optimize heating schedules.

Thermostat Solutions: Precision Control with Sensors and Relays

For spaces where temperature precision matters – like a living room or nursery – a thermostat-like setup offers the best comfort. Shelly devices let you build a custom thermostat system without buying a proprietary unit. The approach combines a temperature sensor (like the Shelly H&T series, sold separately), a relay to switch the heating, and a logic controller – which can be the Shelly Uni. The Shelly Uni acts as a versatile input/output module: it can read analog sensors (e.g., NTC thermistors) and control a relay based on temperature thresholds, all handled locally via scripting or cloud automation.

If you prefer a visual interface, the Shelly Wall Display XL Black can serve as a central thermostat panel. It shows room temperature, humidity, and lets you adjust heating modes manually. Paired with the Shelly PM Mini Gen3 x2 (for energy monitoring) and a relay, it forms a complete smart thermostat system. This modular approach gives you flexibility: you can start with just a relay and add sensors later, or use the Wall Display as a single-room controller that integrates with your whole-home setup.

• Best for: rooms where you want a set temperature (e.g., 21°C) rather than just on/off.
• Shelly Uni can be programmed with simple thresholds – turn heating on if temp drops below 19°C, off above 21°C.
• Wall Display XL Black provides a user-friendly touchscreen and can control multiple Shelly devices in the room.

Smart Plugs for Portable Heaters: A Quick and Portable Option

Not all heating is built into your home. Portable space heaters, oil-filled radiators, and fan heaters can also be smartened up with a simple smart plug. The Shelly Plug M Gen3 White 4-pack offers a four-pack that can control individual heaters in different rooms. Each plug provides power monitoring and remote on/off control via the Shelly app or voice assistants. This is the easiest entry point for smart heating: no wiring required, just plug the heater into the Shelly Plug and set schedules.

However, smart plugs are limited to simple on/off control – they cannot adjust a heater's thermostat. They work best for heaters that have their own mechanical thermostat (so they turn on when the plug is on). Use them for occasional heating in guest rooms or to pre-heat a home office before you arrive. The energy monitoring feature helps you avoid running the heater unnecessarily, cutting electricity costs without sacrificing comfort.

• Best for: renters, temporary setups, or single-room portable heaters.
• Easy to install: plug and play, no electrical work needed.
• Pro tip: always check that the heater's wattage is within the plug's rated capacity (typically 2300W for the Shelly Plug M Gen3).

How to Choose the Right Shelly Heating Solution for Your Home

The best smart heating solution depends on three main factors: the type of heating system you have, the level of precision you need, and your willingness to do electrical installation. For electric in-floor heating or large electric radiators on a fixed circuit, a relay-based solution with the Ogemray Smart relay 25A or Shelly PM Mini Gen3 x2 is ideal. These devices handle high loads and give you reliable on/off control with energy monitoring. If you want temperature-based automation, combine the relay with a Shelly Uni and an external temperature sensor – this DIY thermostat approach is powerful and cost-effective.

For zonal heating with hot water radiators, a smart TRV (such as Shelly's own model, available separately) would be the natural choice, but if you prefer relay control for electric radiators, the same principles apply. If you just want to add smart control to a portable heater without any wiring, the Shelly Plug M Gen3 White 4-pack is the no-fuss option. Finally, if you want a sleek visual interface for your thermostat, consider the Shelly Wall Display XL Black as your control hub. No matter your choice, all Shelly devices work together in the Shelly ecosystem, so you can start small and expand over time.

Ask yourself: Does your heating run on electricity or hot water? Do you need just on/off or precise temperature? Are you comfortable with basic electrical installation? Your answers will point you to the right product family.

• Electric heating with high wattage → relay (Ogemray Smart relay 25A or Shelly PM Mini Gen3 x2).
• Need temperature precision → add Shelly Uni + sensor for local thermostat control.
• Portable heaters → Shelly Plug M Gen3 White 4-pack.
• Want a wall-mounted thermostat → Shelly Wall Display XL Black.

Integration and Automation Ideas with Shelly Heating Solutions

Once you have your Shelly heating devices installed, the real magic happens through automation. You can create rules like 'turn off the electric heater if a window opens' using a window contact sensor, or 'pre-heat the bathroom floor 30 minutes before your alarm' using the Shelly app or Home Assistant. Because Shelly devices support Wi-Fi, local API, and most also work with MQTT, you can integrate them with almost any smart home system – including Google Home, Alexa, and HomeKit (via Homebridge or native support on newer models).

Energy monitoring is particularly valuable for heating. With the Shelly PM Mini Gen3 x2, you can track daily and monthly consumption per circuit. Combine that with time-based rules – for example, run the underfloor heating only during off-peak electricity hours – and you can significantly cut your bills. The Shelly Uni can also be used to connect a relay that controls a water valve for hydronic systems, opening up even more possibilities. Experiment with scenes: 'Goodnight' can lower all heating setpoints, and 'Away' can turn off all heaters except a frost protection circuit.

• Use temperature data from Shelly sensors to trigger relays dynamically.
• Integrate with solar production: heat when your PV system generates excess power.
• Voice control: 'Alexa, set living room heating to 22°C' works with Shelly relay + temperature sensor.

Shelly gives you the flexibility to build a smart heating system that matches your exact needs – from a simple relay for an electric heater to a full thermostat setup with a touch display. Start by evaluating your home's heating type and your comfort goals. For a versatile starting point that combines high-power control with energy monitoring, the Shelly PM Mini Gen3 x2 is an excellent choice. Explore our complete range of relays, plugs, and sensors to find the perfect fit for every room.