Heat loss & emitters
UFH pipe-length estimate
- where
- pipe length (m)
- active heated area (m²)
- pipe centre spacing (mm)
- total connection tails (m)
Explain this equation
Estimates the length of underfloor heating pipe needed for an area at a chosen pipe spacing. Use it to estimate coil quantities and number of loops.
A is the active heated area. s is the centre-to-centre spacing between pipe runs, in millimetres. L_tails is the extra pipe needed to run from the manifold to the heated area and back.
Laying pipe in parallel runs, each metre of pipe covers a strip one spacing wide, so the length is area divided by spacing. The 1000 converts the spacing from mm to metres. The tails are then added.
Sense check: 20 m² at 150 mm spacing needs about 133 m plus 6 m of tails, about 139 m. At 150 mm that is roughly 6.7 m per m²; at 100 mm it is 10 m per m².
Watch out: this ignores edge geometry and bends. Loop length limits, pressure drop and floor output need manufacturer design.
Enter your values to see the result.
Good to know
Area/spacing estimate only. Edge geometry, bends, loop limits, pressure loss and floor output need manufacturer design.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.