Hydronic underfloor heating is a type of heating system where the heat energy originates under the entire floor of a house, and radiates upward. It is different than more traditional heating systems, where a heater inside of a room creates heat, because heat radiates upward from the whole floor area, so it doesn’t have to be circulated throughout the house using air currents. The heat energy in a hydronic heating system is distributed throughout the floor of the house with tubes of heated water, which are installed across the whole floor. Heat transmits from the water to the tube that carries it, and from the tube the floor mass. From there it radiates upward into the room. The water can be heated using solar power, electric water heaters, wood burning stoves, or geothermal energy.

Hydronic underfloor heating systems are more efficient than the traditional style of heater because the warm air is more concentrated closer to the floor, rather than closer to the ceiling. With a traditional system, heat is generated in one area and air currents are used to move it around the house, so, because warm air rises, this type of system causes a much higher concentration of warm air closer to the ceiling, where people living in the house cannot feel it. Because so much of the heat energy distributed by a traditional heating system flows to the ceiling, a greater total amount of heat energy is needed to reach the areas that are occupied by the people living in the house. With a hydronic heating system, the heat energy is generated across the whole floor and rises into the airspace in the room. Because the warm air cools as it rises, hot air never collects near the ceiling, so less total heat energy is needed to keep the house comfortable for people to live in.

Since extensive excavation of the floor is needed to install a hydronic heating system, the initial installation is very expensive, but, since it uses less total energy than other methods of heating a house, it saves money in the long run. Because installation is so expensive, it usually takes a very long time to save money with a hydronic heating system (the length of time it takes to pay off depends on how much airspace there is in the house in question). Before you decide to buy a hydronic heating system for your home, consider how long you plan to live in that house, because it will only save you money if you continue to live there for many years.