Smart Thermostat Retrofit: Step by Step

By Rollei | Published: 2026-10-26

Category: How-to Guides

Learn how to easily replace your old thermostat with a smart one. Step-by-step instructions for a quick and safe setup.

Quick Answer

You can replace your old thermostat with a smart model in about 15 minutes using basic tools. Follow our step-by-step guide for a safe and successful installation.

Why Retrofit a Smart Thermostat?

A smart thermostat lets you control your heating from your phone, set schedules, and potentially save up to 30% on heating costs compared to traditional models. It's a simple upgrade that adds comfort and efficiency to your home.

What You'll Need

You'll need the smart thermostat itself, a screwdriver (usually Phillips), and possibly a small level. Most smart thermostats come with the necessary screws and adapters. Check your current thermostat's wiring before starting.

Installation Steps

Turn Off Power: Locate your heating system's circuit breaker or fuse and turn off the power to the thermostat. This ensures safety while working with electrical connections. Common mistake: Forgetting to turn off power can lead to electric shock or damage to the thermostat.
Remove Old Thermostat: Unscrew the cover plate of your old thermostat. Take a photo of the wiring before disconnecting any wires. Then, disconnect the wires and remove the old base plate. The photo serves as a reference if you forget which wire goes where.
Install New Base Plate: Use the included screws to mount the new thermostat's base plate to the wall. Use a level to ensure it's straight. Feed the wires through the opening. A crooked base plate can make the thermostat look uneven and affect sensor readings.
Connect Wires: Match the wires from your wall to the labeled terminals on the new base (e.g., L, N, S1, S2). Tighten each screw securely. Refer to the photo you took earlier if needed. Loose connections can cause intermittent heating or thermostat failure.
Attach Thermostat and Restore Power: Snap the smart thermostat onto the base plate until it clicks. Turn the power back on at the circuit breaker. The display should light up. If the display doesn't turn on, double-check the wiring and power supply.
Configure via App: Download the companion app (if applicable) and follow the on-screen instructions to connect the thermostat to your Wi-Fi and set your heating schedule. Common mistake: Skipping the Wi-Fi setup means you lose remote control features.

Product Facts

Smartes Thermostat: The Rollei Smart Thermostat can help you save up to 30% on heating costs compared to conventional thermostats. This means a quick upgrade can lead to significant long-term savings on your energy bills.
Smartes Thermostat