Floor heating

Application Guide

Underfloor heating with Shelly

Control water-based and electric underfloor heating with Shelly relays, Wall Display, and the Smart Control app.

Last updated: April 2026

Introduction

Shelly can control both water-based and electric underfloor heating through the thermostat function in the Shelly Smart Control app, or through a Shelly Wall Display with built-in floor-heating controller.

This guide covers both heating types, recommends the right relay for each scenario, and explains sensor and wiring choices.

Quick start — find your scenario

Water-based heating?

Use Shelly Pro 3 (24 V / 230 V) or Pro 4PM (230 V with metering)

DIN-rail mounting at the manifold

Read more →
Electric heating?

Use Shelly 1PM Gen4

In-wall mounting per room

Read more →
Want a standalone thermostat?

Use Shelly Wall Display

Built-in floor-heating controller, no app required

Read more →

Compatibility at a glance

Match your heating type to the recommended Shelly device. All four options can be controlled from the Shelly Smart Control app.

Heating type Recommended device Channels / Zones Max load per channel Mounting Power metering Notes
Water-based, 24 V actuators Shelly Pro 3 3 zones Dry contact (external supply) DIN-rail No Use external supply for 24 V or 230 V actuators.
Water-based, 230 V actuators Shelly Pro 4PM 4 zones 16 A / 3,680 W DIN-rail Yes Built-in 230 V switching, per-zone consumption logged.
Electric underfloor heating Shelly 1PM Gen4 1 zone 16 A / 3,680 W In-wall Yes One device per room, decentralised control.
Standalone alternative Shelly Wall Display 1 zone 16 A In-wall Yes Built-in floor-heating controller, requires external sensor.

Water-based underfloor heating

When to use this approach: water-based systems with manifolds in central locations like utility rooms, basements, or distribution cabinets. Each loop is controlled by an actuator that opens or closes the flow on the manifold. Centralised control means one Shelly Pro device handles multiple zones.

Water-based systems are typically controlled centrally from a manifold. A DIN-rail Shelly Pro relay switches the actuators that open and close each loop.

Choose your relay

Match the relay to the actuator voltage and your metering needs:

  • Shelly Pro 3 — three potential-free dry contacts. Suitable for 24 V or 230 V actuators (no built-in supply). Use this when you have an external supply on the manifold or need maximum flexibility.
  • Shelly Pro 4PM — four channels with built-in 230 V switching and per-channel power metering. Use this when you want consumption tracking per zone.

Both mount on DIN-rail, which fits naturally next to the manifold or in the distribution cabinet.

Choose your temperature sensor

Pick a sensor based on whether you want to read floor or room temperature:

Wiring

Connect the actuators to the Shelly Pro outputs and bring the manifold’s circulation pump under the same controller. Use the manifold’s neutral bar for the actuator return.

O1–O4
Actuator outputs (one per zone)
L
Line — common feed for 230 V actuators
N
Neutral conductor
S1–S4
Optional inputs (e.g. external thermostats)

Verify polarity and torque each terminal to the value on the device label before re-energising the circuit.

Two Shelly Pro DIN-rail devices connected to a manifold with six actuators and a circulation pump.
Two Shelly Pro relays driving six actuators on a manifold, with the circulation pump on the same controller.

Configure the thermostat in the Shelly Smart Control app

  1. Open the Shelly Smart Control app and go to Home.
  2. Tap Add new → Thermostat.
  3. Select the actuator output (Pro 3 or Pro 4PM channel).
  4. Select the temperature sensor.
  5. Set the target temperature and configure a weekly schedule.

The same setup is available on the web at control.shelly.cloud.

Electric underfloor heating

When to use this approach: electric heating mats or cables installed in bathrooms, kitchens, or other rooms where you want fast, responsive heating. Each room has its own thermostat location, and each Shelly 1PM Gen4 lives in the back-box behind that thermostat. Decentralised control means one device per room.

Electric systems are usually controlled per room. An in-wall relay sits behind the existing thermostat and switches the heating element directly.

Choose your relay

Shelly 1PM Gen4 handles loads up to 16 A / 3,680 W, fits in a standard back-box, and reports real-time power consumption. One device per room keeps wiring simple and lets each room run on its own schedule.

Temperature sensor

Pair the relay with the Shelly Plus Add-On and a DS18B20 probe placed in the screed.

Why a floor sensor matters for electric heating: the heating element heats the floor surface directly. Without a floor sensor you risk overheating sensitive flooring, and a room-only sensor cannot guarantee a comfortable surface temperature on cold mornings. A floor sensor delivers both safety and comfort.

Wiring

Run mains into the Shelly 1PM Gen4 and switch the heating element from the output. Wire the DS18B20 probe to the Add-On.

L
Line in (110–240 V AC)
N
Neutral conductor
O
Output to the heating element
SW
Optional manual switch input
VCC
DS18B20 red — 3.3 V supply
DATA
DS18B20 yellow — 1-Wire data line
GND
DS18B20 black — ground
Shelly 1PM Gen4 and Shelly Plus Add-On with a DS18B20 floor probe embedded in an electric heating mat.
Shelly 1PM Gen4 switches the heating element; the Add-On reads the DS18B20 probe in the floor.

Configure the thermostat

Follow the same flow as for water-based heating: Add new → Thermostat → select the 1PM Gen4 output → select the DS18B20 sensor → set the target temperature and schedule.

Wall Display as standalone controller

When to use this approach: when you want a physical thermostat on the wall that works independently of the Shelly app. The Wall Display has a built-in floor-heating controller that handles scheduling, sensor reading, and relay control directly — no app or cloud connection required for daily operation.

The Shelly Wall Display ships with a built-in floor-heating controller and can act as a fully standalone thermostat — no Smart Control app thermostat required.

Pair an external sensor

The Wall Display needs an external temperature sensor. Use a Shelly BLU H&T ZB — it pairs locally over Bluetooth directly with the Wall Display, with no cloud dependency.

In the Wall Display interface, open Settings → Bluetooth devices → Add, then put the BLU H&T ZB into pairing mode.

Activate the floor-heating controller

Open the Wall Display home screen, choose the Floor heating tile, then assign the BLU H&T ZB as the temperature source and the chosen relay output as the actuator. Set target temperature and schedule directly on the device.

Video tutorial

Watch a step-by-step walkthrough of the Thermostat function in the Shelly Smart Control app. The video covers both water-based and electric underfloor heating, including how to pair a relay with a temperature sensor and set up a weekly schedule with night-time setback.

By ShellyGuide on YouTube

Tips & best practices

  • Use schedules for night setback. Drop the target by 2–3 °C overnight to cut consumption without losing morning comfort.
  • Tie heating to electricity prices. Use Shelly Scripts or scenes to lower the setpoint during peak hours and pre-heat in cheap windows.
  • Keep wood floors below 27 °C. Set a hard ceiling on the floor sensor to protect parquet and engineered wood from drying out.
  • Validate load with power metering. Compare the rated and measured load on the first run — a large discrepancy points to a wiring or actuator issue.
  • Combine floor and room sensors where possible. Use the floor sensor as a safety limit and the room sensor for the comfort target.