Why is my central air drawing air back out of the chimney (b vent)?

Even after I installed a fresh air intake it is still drawing air back out of the chimney and rejecting the exhaust from the hot water tank. I did notice after having a new b vent installed they did not install the drip plate, this can't be code?Its a direct run into the furnace and tank. Is this also my vent problem? Unlikely huh WTF is going on.