  We consider a harmonic chain of $N$ oscillators in presence of a disordered
magnetic field. The ends of the chain are connected to heat baths and we study
the effects of the magnetic field randomness on the heat transport. The
disorder, in general, causes localization of the normal modes due to which a
system becomes insulating. However, for this system, the localization length
diverges as the normal mode frequency approaches zero. Therefore, the low
frequency modes contribute to the transmission, $\mathcal{T}_N(\omega)$, and
the heat current goes down as a power law with the system size, $N$. This power
law is determined by the small frequency behaviour of some Lyapunov exponent,
$\lambda(\omega)$, and the transmission in the thermodynamic limit,
$\mathcal{T}_\infty(\omega)$. While it is known that in the presence of a
constant magnetic field $\mathcal{T}_\infty(\omega)\sim \omega^{3/2},~
\omega^{1/2}$ depending on the boundary conditions, we find that the Lyapunov
exponent for the system behaves as $\lambda(\omega)\sim\omega$ for
$\expval{B}\neq 0$ and $\lambda(\omega)\sim\omega^{2/3}$ for $\expval{B}=0$.
Therefore, we obtain different power laws for current vs $N$ depending on
$\expval{B}$ and the boundary conditions.
