Hydronic Radiant Floor Heating Calculator
Estimate tubing length, flow rates, and heat output for underfloor heating. Select flooring types and room dimensions for accurate material requirements.
Room Config
About
Hydronic radiant floor heating is one of the most efficient ways to heat a home, using warm water circulated through PEX tubing embedded in the floor. However, designing the system requires precise calculations to ensure the floor delivers enough heat (BTU/h) to overcome the room's heat loss.
This tool helps contractors and DIYers estimate the critical components of a loop. The type of finished floor covers (tile, carpet, wood) significantly impacts heat transfer—carpet, for example, acts as an insulator and requires higher water temperatures. By inputting room dimensions and flooring type, you can calculate the necessary tubing length, expected heat output, and flow rate (GPM) to size your pump correctly.
Formulas
Total tubing length is derived from the area and spacing, plus leader length to the manifold:
The required flow rate in Gallons Per Minute (GPM) is based on the heat load and the temperature drop (Delta T), usually 20°F:
Reference Data
| Flooring Material | R-Value | Heat Transfer | Max Temp Rec. |
|---|---|---|---|
| Ceramic Tile | 0.25 | Excellent | 85°F (29°C) |
| Concrete (Polished) | 0.05 | Superior | 85°F (29°C) |
| Hardwood (3/4") | 0.75 | Fair | 80°F (27°C) |
| Laminate | 0.50 | Good | 82°F (28°C) |
| Carpet (Heavy Pad) | 2.00 | Poor | 85°F (29°C) |
| Vinyl Sheet | 0.20 | Good | 85°F (29°C) |
| Engineered Wood | 0.40 | Good | 80°F (27°C) |
| Stone / Slate | 0.10 | Excellent | 85°F (29°C) |