How to Install Underfloor Heating

How to Install Underfloor Heating: A Step-by-Step Guide for Trades

Understanding how to install underfloor heating correctly is paramount for ensuring system efficiency, longevity, and client satisfaction. While specific steps vary between wet (hydronic) and electric systems, core principles apply across all installations. This guide provides a foundational overview, focusing on best practices for UK tradespeople.

Initial Planning and Preparation

Before any physical installation begins, thorough planning is essential:

  • System Design: Always start with a detailed UFH design. This specifies pipe layouts, manifold positioning, heat loss calculations, and zone requirements. For wet systems, the design dictates pipe spacing (centres) crucial for heat output.
  • Subfloor Preparation: Ensure the subfloor is clean, level, and structurally sound. Address any damp issues immediately. A stable, prepared base prevents problems later.
  • Insulation Installation: Install high-quality subfloor insulation. This critical step directs heat upwards into the room, preventing energy loss downwards into the floor structure or ground. Use appropriate insulation boards (e.g., rigid PIR boards, foiled insulation) that offer adequate thermal resistance.
  • Perimeter Edge Insulation: Fit perimeter edge insulation around the room’s perimeter. This compensates for thermal expansion of the screed (in wet systems) and acts as a thermal break, reducing heat loss through walls.

Installing Wet (Hydronic) Underfloor Heating

Wet UFH installations involve pipework and manifold setup:

  • Manifold Positioning: Mount the manifold in an accessible location, often in a utility cupboard or plant room. Connect it to the heat source (boiler/heat pump) and ensure easy access for future balancing and maintenance.
  • Pipe Laying: Lay the UFH pipework according to the design plan. Common methods include clipping pipes to insulation, routing them within pre-formed grooved insulation boards, or securing them to a mesh grid. Ensure correct pipe spacing and avoid kinks.
  • Connecting Pipes to Manifold: Connect each pipe circuit securely to the manifold’s flow and return ports, using compression or push-fit connectors as appropriate. Label each circuit clearly for easy identification of zones.
  • Pressure Testing & Screeding: Crucially, pressure test the system with water (and often compressed air) before screeding. Maintain pressure during screeding to identify any leaks immediately. Once the screed cures fully (allow adequate drying time), the system is ready for initial commissioning.

Installing Electric Underfloor Heating

Electric UFH installations are typically quicker and simpler:

  • Membrane & Cable Laying: Lay the electric heating mats or loose cables directly onto the insulated subfloor. Ensure even spacing if using loose cable. Do not overlap heating elements.
  • Sensor Placement: Install the floor temperature sensor (probe) midway between two heating runs, centrally within the heated area. This ensures accurate temperature readings for the thermostat.
  • Electrical Connection: A qualified electrician must connect the heating mat/cable to the mains power supply via a fused spur and directly to the dedicated UFH thermostat. Adhere strictly to IET Wiring Regulations (BS 7671).
  • Flooring Application: Once connected and continuity-tested, apply a flexible levelling compound or adhesive over the mats/cables before installing the final floor finish (tiles, laminate, engineered wood).

Final Commissioning

For both systems, proper commissioning is vital. This involves purging air, balancing circuits (wet systems), testing electrical continuity and resistance (electric systems), and programming thermostats. Always follow manufacturer guidelines precisely to ensure efficient operation and validate warranties. Mastering these steps ensures a professional and reliable underfloor heating installation every time.

For detailed product-specific installation guides, explore our full range of underfloor heating kits, or browse installation accessories that simplify the process. Our technical team is also available to assist with complex queries.