Hydronic Radiant Walls

Hydronic heating systems with warm water tubes installed within the surface of walls, to radiate heat into the room. This is a seamless and potentially even invisible way to heat a room, using a large surface area to radiate heat at a lower water temperature. The water can be heated by any heat source, and is circulated through the wall tubes with a circulation pump.

Radiant walls can be a feasible choice for major renovations and retrofits. If you install a radiant wall system, try using an interior wall, so that any heat lost into the wall is still in the house. If it's installed on an exterior wall, it needs to be extra well insulated, and preferably have a heat reflector, because the elevated temperature in the wall cavity will increase heat loss to the outside.

By having a larger surface area than baseboard radiators, radiant walls can distribute enough heat using a lower temperature of water, which increases efficiency and the ability to use various heat sources, such as geothermal energy, heat pumps, and solar water heating. On the down side, note that the radiant wall will radiate heat towards the outside of the wall as well as the inside, which increases heat loss to the exterior and decreases efficiency.

In the 1600s in Europe, "fruit walls" - stone walls built throughout orchards of fruit trees - were heated naturally by the sun and moderated the swing in temperature from day to night. These structures provided protection from frost and wind, allowing Mediterranean fruits like peaches to be grown in great quantities in colder areas like northern France, the Netherlands, and England.