Step-by-step installation: smart thermostats

From wiring to configuration: how to install and commission smart controls

Smart thermostats have become the new standard for modern heating systems, offering homeowners flexibility, control and comfort. For installers, they represent both an opportunity and a challenge: when fitted correctly, they reduce callbacks and improve customer satisfaction, but a rushed installation can lead to wiring errors, Wi-Fi issues or unhappy customers.

This article provides heating professionals with a complete step-by-step guide to installing smart thermostats in UK systems, covering preparation, wiring, configuration, testing and troubleshooting. It also includes best practices to ensure every installation is efficient, compliant and professionally delivered.

If you need to review the differences between smart and traditional models before installation, our thermostat guide for installers provides a complete overview.

[Table of Contents]

• Preparing for the installation
• Installing the thermostat
• Configuration and setup
• Support and troubleshooting
• Why professional installation adds value to customers

Preparing for the installation

Preparation is the foundation of a smooth installation. Before wiring, installers must confirm compatibility, prepare tools and brief the homeowner. This avoids delays, technical errors and unnecessary frustration later in the process.

System type compatibility checklist

Before beginning, installers must identify the heating system type. Smart thermostats such as the T6 and evohome work well with combi boilers, open-vented systems, system boilers and heat pumps, but wiring and configuration differ for each.

Key checks include:

• does the system have a combi boiler or a separate hot water cylinder?
• is zoning already in place, or will the smart thermostat manage multiple zones?
• for heat pumps, is the system ready for low-temperature operation and zoning?

Wiring considerations for boilers and heat pumps

Correct wiring is crucial. Installers should:

• review the manufacturer’s wiring diagrams.
• confirm whether the thermostat requires a mains or low-voltage connection.
• check that the boiler interface supports on/off, OpenTherm or other communication protocols.
• assess if additional relays or receivers are required for multi-zone systems.

Necessary tools and common pitfalls

Standard tools include screwdrivers, wire strippers, a drill, a voltage tester and wall plugs. Common pitfalls include cutting wires too short, failing to isolate power before starting, or using incorrect terminals. Preparation avoids wasted time on site.

Installing the thermostat

Mounting and wiring are critical stages in the installation. A secure, accurate setup ensures the system functions properly and prevents early faults that could generate return visits.

Mounting and connection process

1. Isolate the power supply to the boiler.
2. Fix the thermostat backplate or receiver to the wall, ideally 1.5m above floor level in a representative room.
3. Connect wiring according to the diagram, ensuring secure terminals.
4. Restore power and check for initial device activation.

Powering on and initial tests

Once wired, power on the thermostat and receiver. Most smart thermostats include a guided setup process. Installers should follow prompts carefully, verifying that the boiler responds correctly to heating commands.

Key differences between models (e.g. T6, evohome)

• T6R-HW: best suited for single or twin-zone control (heating or heating and hot water); simple to install and app-based configuration.
• evohome: designed for multi-zone systems with wireless radiator controllers (e.g. HR92). Requires more planning but offers full home zoning.

Installers can position evohome as a premium option for larger homes, while the T6 is a reliable upgrade for smaller properties or straightforward systems.

Configuration and setup

Configuration defines how the system will be used day-to-day. Installers must ensure schedules, zoning and connectivity are tailored to the homeowner’s needs.

Connecting to Wi-Fi and apps

One of the most common challenges is connecting the thermostat to the homeowner’s Wi-Fi. Best practices include:

• positioning the thermostat or hub within a strong signal range.
• using the Resideo app for guided setup.
• ensuring the homeowner has login details ready.

Setting schedules and zones

Schedules are essential for energy optimisation. Installers should demonstrate how to:

• set heating programmes for weekdays and weekends.
• configure individual zones (in evohome systems).
• adjust temperatures manually if needed.

Customers appreciate hands-on guidance; it reduces confusion and future complaints.

Safety checks and homeowner walkthrough

Before leaving, installers should:

• test the system at different setpoints to ensure correct operation.
• show customers how to override schedules.
• highlight energy-optimisation features without making absolute promises on savings.
• provide documentation and Resideo support links.

Support and troubleshooting

No installation is complete without support resources. Installers should provide customers with documentation and be ready to solve common issues during setup.

Common setup issues and solutions

• Wi-Fi drops: suggest moving the router closer or using extenders.
• Incorrect wiring: double-check diagrams and terminal use.
• Boiler not responding: verify relay or receiver pairing.
• App login problems: assist the customer in creating or recovering their account.

How Resideo supports installers (documentation, academy, FAQs)

Resideo provides installers with detailed manuals, online FAQs and training at the Resideo Academy. Training sessions cover practical skills, troubleshooting techniques and advanced configurations.

Best practices to avoid failure costs

By investing extra time in preparation and customer education, installers reduce the risk of call-backs, which are often caused by incomplete setup or unclear handover. Fewer call-backs mean more time available for new projects and happier customers.

Why professional installation adds value to customers

While some homeowners consider DIY installation, professional fitting guarantees safety, compliance and system optimisation. Installers can emphasise the following benefits:

• correct wiring and safe isolation procedures.
• optimal placement for accurate readings.
• configuration tailored to the customer’s lifestyle.
• long-term reliability with fewer technical issues.

Professional installation also builds trust. Customers who see their installer as a partner are more likely to request future upgrades, from TRVs to full zoning systems.

Discover more on Resideo Academy.

Explore smart thermostat solutions: Resideo Smart Thermostats.