what could be the cause of a hot wheel?

make sure that brake pedal return spring is not broken this can allow system to pressurise after using brakes quite a lot.not quite sure of your particular model, but make sure linkage to servo is not siezing-up on any of the joints.

k
July 2009

The brakes are sticking on, Steve either due to the caliper pistons sticking, or the caliper sliding pins likewise - however you say that you have replaced the caliper. Was it a new one? If it was, after driving the van, jack it up on that side and see if the wheel spins freely. If not, undo the bleed nipple a fraction, let a bit of fluid out and see if that works. If it does, then either you have a swollen and blocked flexible pipe or a master cylinder fault.

John
July 2009