One kg of steam is equivalent to 27 kg of thermic fluid for delivering the same heat content. For heating applications less than 200o C, steam is preferable to thermic fluid as heating media
Of all heating media, steam has the highest energy content. To go by numbers,
1 kg of steam has around 540 Kcal of heat content while 1 kg of thermic fluid
(high temperature oils) has around 20 Kcal of heat content.
This implies that for every 1 kg of steam you need 27 kg of thermic fluid to
deliver the same heat content. Therefore the quantity of thermic fluid to attain a
specific temperature would be 27 times more than steam.
For processes requiring very high temperatures (in the range of 250°C), high
pressure steam is required. Even though steam is the most efficient energy
carrier, the cost involved to manufacture the equipment required to handle
such high pressures makes thermic fluid commercially viable.