Fortunately, there are already several solutions to this problem. Some routers are capable of handling both external HDDs and torrents. An even better solution is a NAS. A NAS is a network storage device that can hold up to 2, but some can have multiple HDDs that can be used in RAID mode to help store data securely. A good NAS handles HDD cooling and is of course also capable of handling torrents. You can manage your data at up to gigabit speeds on an internal network. I use THIS and I am very happy with it.