Underfloor Heating Outputs and Heat Losses

Water underfloor heating outputs are quoted in W/sqm.  The maximum underfloor heating output for underfloor heating in a concrete floor is 100 W/sqm, the maximum heat output for a timber suspended floor is 70 W/sqm.

Watts is a measure of heat energy required.  The higher the W/sqm, the more energy is used by the heat source to operate the underfloor heating water system.

A heating engineer should always do the heat loss calculations for each room that requires underfloor heating.  Each building element has a particular U-Value.  The U-Value is a measure of the thermal efficiency of a material.  The lower the U-Value, the less underfloor heating energy is wasted to the outside air.

In the UK, the average home built to current building regulations would require approximate 50 – 60 W/sqm for the underfloor heating system to operate.

The water temperature in the underfloor heating system can be increased so the underfloor heating system can provide more heat output.  Even by adjusting the mixing valve with 5 degree C will produce almost 20 % more heat output.

Water flow rate for the individual underfloor heating loops can also be adjusted to provide more heat output.

Our pipe spacing for our water underfloor heating is c/c 200 mm and this is the optimum pipe spacing for our 16 x 2 mm underfloor heating system.  This pipe spacing will even work with heat pumps.

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