Radiant forced hot water is becoming popular again. Piping is installed in either the floor or ceiling and warms the areas where they are installed. Although this is not the most efficient installation, it is the most cosmetically appealing because the convection piping is not visible and it is the most comfortable when installed correctly.  Older systems used copper tubing in the slab of the home to warm it like a hot plate. These systems however are prone to expensive maintenance after 20 or more years. When a leak occurs it is both difficult to locate or repair. Many of the these installations have been converted to baseboard convection because of costly repairs. Most modern installations use industrial plastic tubing which will be more durable than the previous copper tubing installations.