Abstract
Horizontal parts of long distance coronal loops are studied. Under currently verifiable hypotheses, the conclusion is drawn that the matter is in isothermal and static state. Therefore the heating has only to balance the radiative loss. Applying this result to different types of steady state loops, the heating can be related to the loops' sizes and ages. Another application to both phases, before and after an enhancement of X-rays emission, reveals a change in the amount of heating.
