  Instantons in pure Yang-Mills theories on partially periodic space
$\mathbb{R}^3\times S^1$ are usually called calorons. The background
periodicity brings on characteristic features of calorons such as non-trivial
holonomy, which plays an essential role for confinement/deconfinement
transition in pure Yang-Mills gauge theory. For the case of gauge group
$SU(2)$, calorons can be interpreted as composite objects of two constituent
"monopoles" with opposite magnetic charges. There are often the cases that the
two monopole charges are unbalanced so that the calorons possess net magnetic
charge in $\mathbb{R}^3$. In this paper, we consider several mechanism how such
net magnetic charges appear for certain types of calorons through the ADHM/Nahm
construction with explicit examples. In particular, we construct analytically
the gauge configuration of the $(2,1)$-caloron with $U(1)$-symmetry, which has
intrinsically magnetic charge.
