Calidarium

The thermæ conſiſted of a great variety of parts and conveniences; […] the calidaria, where the water was warmed for the baths; […]

Source: wiktionary

From this place the party again diverged, according to their several fancies, some to the sudatorium, which answered the purpose of our vapour-baths, and thence to the warm-bath itself; those more accustomed to exercise, and capable of dispensing with so cheap a purchase of fatigue, resorted at once to the calidarium, or water-bath.

Source: wiktionary

Between the two calidariums serving the mens's^([sic]) and women's sections is the heating plant where the furnace and the three big cylindrical boilers (one for warm, one for hot and one for very

Source: wiktionary

A container of fine oil had been left on a shelf near the calidarium, so the king and the tribune helped themselves to a liberal amount.

Source: wiktionary