Underfloor heating system

How is the water in Underfloor Heating System Heated?

Underfloor Heating System: Water Heating Process

The water in an underfloor heating system is heated using sources like boilers, heat pumps, or solar thermal systems. These sources generate heat, which is transferred to the water. The heated water circulates through concealed pipes, radiating warmth upward to provide effective and energy-efficient heating.

Heat Source Selection:

The first step in heating the water for an underfloor board insulation involves selecting an appropriate heat source. Common heat sources include boilers, heat pumps, and even solar thermal systems. The choice depends on factors such as energy efficiency, available resources, and the specific heating requirements of the building.


Boilers are a traditional yet effective heat source for water underfloor heating. They generate hot water by burning fuel (such as natural gas or oil) or through electric resistance. Subsequently, circulate the produced hot water through the underfloor pipes to transfer heat to the floor and, consequently, to the room.

Heat Pumps:

Heat pumps are eco-friendly alternatives that extract heat from the environment and transfer it to the water. They work by compressing and expanding a refrigerant gas, absorbing heat from the air, ground, or water sources. Utilize this heat to warm the water, and subsequently, circulate it through the underfloor pipes.

Solar Thermal Systems:

Solar thermal systems utilize solar energy to heat a fluid (often a mixture of water and antifreeze) through solar collectors. Transfer the heated fluid to a heat exchanger, which then warms the water within the underfloor board insulation. This approach aligns with sustainable practices and reduces reliance on conventional energy sources.

Water Heating Process:

Once the heat source is selected, the water heating process begins.

  • Heat Generation:
    In a boiler system, the chosen fuel is burned, generating heat that warms the water in the boiler. For heat pumps, the refrigerant’s compression and expansion cycle extracts and transfers heat to the water. Solar collectors absorb sunlight, raising the temperature of the fluid within the collector.
  • Heat Transfer:
    The generated heat is transferred to the water that will circulate through the underfloor pipes. This can occur through direct contact (as in boilers) or through a heat exchanger (as in heat pumps and solar thermal systems).
  • Circulation:
    A pump is used to circulate the heated water from the heat source to the underfloor pipes. The water travels through a closed-loop network, ensuring consistent and efficient heat distribution.
  • Regulation and Control:
    Thermostats and control systems monitor the temperature of the water and adjust the heat source accordingly. This prevents overheating and maintains a comfortable indoor environment.

Efficiency and Sustainability:

The method of heating the water significantly impacts the system’s efficiency and sustainability. Recognize the lower environmental impact and energy efficiency of heat pumps and solar thermal systems when compared to traditional boilers.


The process of heating water for an underfloor insulation board involves selecting a suitable heat source, generating heat, transferring it to the water, and ensuring controlled circulation. The chosen heat source, whether a boiler, heat pump, or solar thermal system, influences the system’s efficiency and environmental impact. By understanding these heating mechanisms, one can optimize the performance of a wet underfloor heating while promoting energy efficiency and comfort.

1 Comment

  1. Joseph on 05/09/2023 at 11:27 AM

    Can I use a solar thermal system to heat the water for underfloor heating in any climate, or is it only effective in sunny regions?

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