Carvalhal left Wednesday in December after a poor start to the season and, although he has inspired a turnaround at the Swans since his appointment, he was unable to get the better of his former employers on this occasion.
Few would have guessed Swansea were the Premier League side during the early exchanges, as the hosts took charge of possession and went close to netting - Adam Reach forcing Kristoffer Nordfeldt into a smart save in the sixth minute.
That was hardly a sign of things to come, however, with neither side managing another shot on target until the 37th minute, when Mike van der Hoorn drew a remarkable Cameron Dawson save from point-blank range.
Swansea's superior quality began to shine through a little more after the restart, with Wayne Routledge and Luciano Narsingh starting to see more of the ball and posing a threat out wide.
For all their improvement, shots on target remained rare for the Swans, with their next reasonable chance not arriving until the 71st minute, when Jordan Ayew shot straight at Dawson after good link-up play with Routledge.
Atdhe Nuhiu then twisted and turned in the area before getting a shot away soon after, but Nordfeldt kept the effort out and that ultimately secured Swansea a replay.