The invention is directed to modular radiant heat panel system. In the preferred embodiment, the system comprises multiple radiant heat transfer panels (16), each of the panels having a thermal mass (18) and a conduit channel (20); a fluid conduit (21), the conduit communicating with an apparatus (23) for heating fluid (22) in the conduit; the multiple panels positioned adjacent each other such that the conduit extends through a series of the conduit channels; the panels, conduit and apparatus so configured and arranged to permit heat transfer from the fluid to the thermal mass of the panel, whereby heat radiates from the panel. The present invention also discloses a radiant heat transfer panel for engagement with a fluid conduit comprising: a formed tray (24); the tray defining a thermal volume (17) and a conduit channel; the volume containing a thermal mass; and the channel, volume and thermal mass configured and arranged to permit heat transfer between the conduit and the thermal mass. The invention also discloses a method for installing a modular radiant heat panel system comprising the steps of: providing an under-layer having a given area (44); providing multiple panels having a thermal mass and a conduit channel; providing conduit; position the conduit over or under the under-layer in a predetermined pattern; and positioning the panels on or under the under-layer such that the conduit extends through at least a portion of the conduit channel of the panels.