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Hydronic underfloor heating is one of the most efficient and comfortable ways to heat a space. When installed correctly, it delivers even heat distribution, quiet operation, and long-term reliability.
This guide walks through the key steps of installing a panel-based hydronic radiant system, with a focus on proper preparation, installation, and startup.
Before You Start: Planning Is Everything
A successful radiant system begins before any materials are installed.
Pre-Installation Checklist
- Heat load calculation completed
- System layout and loop design finalized
- Manifold location determined
- Tubing size and loop lengths defined
- Mechanical system selected (boiler, mixing, controls)
- Materials staged and ready on site
Proper planning ensures the system performs as intended and avoids costly adjustments later.
7-STEP INSTALLATION FLOW
Prepare Subfloor
Level, dry & clean
Lay Insulation
50mm rigid foam
Fix Panels
Clip to insulation
Run PEX Tubing
Follow loop design
Pressure Test
6 bar / 30 min
Pour Screed
Cure 4–6 weeks
Commission
Balance & thermostat
Tools and Materials
Typical materials include:
- Radiant panel system (such as WBI RadiantBoard, ThermalBoard, or EPS panels for slab applications)
- PEX tubing (size per system design)
- Manifold and connection fittings
- Fasteners or approved adhesive (depending on installation type)
- Basic layout, cutting, and measuring tools
Step 1: Prepare the Subfloor
The subfloor must be ready before installation begins.
- Ensure the surface is clean, dry, and structurally sound
- Check for flatness and correct any uneven areas
- For concrete, verify moisture conditions
- For wood subfloors, confirm proper fastening and integrity
A properly prepared surface ensures good panel contact and consistent system performance.
Step 2: Install the Radiant Panels
- Lay out panels according to the system design
- Align panels carefully to maintain proper tubing paths
- Fasten panels using approved methods based on the substrate
- Keep layout consistent to match the tubing plan
Taking time here makes tubing installation faster and more accurate.
Step 3: Install the PEX Tubing
- Follow the system layout when installing tubing
- Press tubing fully into panel grooves to ensure proper contact
- Avoid kinks and sharp bends
- Maintain loop lengths and spacing as specified in the design
Each loop should be installed cleanly and consistently to ensure balanced system performance.
Step 4: Connect to the Manifold
- Connect each tubing loop to the manifold
- Label circuits clearly for identification
- Use proper fittings and secure all connections
Final mechanical connections should comply with local codes and may require a licensed professional.
Step 5: Pressure Test the System
Before covering the system:
- Perform a pressure test according to PEX manufacturer guidelines and local code
- Maintain pressure for the required duration
- Inspect all connections for leaks
Pressure testing is critical. Fixing issues after the system is covered is much more difficult.
INSTALLATION TIMELINE
Screed cure time dominates the schedule — allow 4–6 weeks minimum.
Step 6: Install Finished Flooring
Once the system passes testing:
- Install flooring according to manufacturer guidelines
- Confirm compatibility with radiant heat
- Follow recommended temperature limits
Common flooring options include:
- Tile
- Luxury vinyl plank (LVP)
- Engineered wood
- Hardwood
Step 7: Commission and Balance the System
After installation is complete:
- Fill and purge air from the system
- Set and verify flow rates at the manifold
- Balance all loops
- Gradually bring the system up to temperature
Important: Increase temperature slowly to protect flooring materials and ensure system stability.
PRE-HANDOVER COMMISSIONING CHECKLIST
Frequently Asked Questions
Key Takeaways
- Proper design and planning are essential for performance
- Subfloor preparation directly impacts results
- Panel systems simplify installation and improve consistency
- Tubing must be installed carefully to avoid damage
- Pressure testing is a required step before covering
- System startup should be gradual and controlled
Final Thought
Installing hydronic underfloor heating is a straightforward process when approached step by step. Attention to detail during planning and installation is what determines long-term performance.
Panel-based systems, such as WBI RadiantBoard and ThermalBoard, are designed to simplify installation while improving heat transfer and overall system efficiency, making them a practical choice for both new construction and retrofit projects.
