Owls boss Chris Turner originally wanted to bring in either Steve Caldwell or Middlesbrough’s Colin Cooper on loan, but set his sights on the younger Caldwell brother after seeing his bids rejected.
Turner had hoped to have the Scotland international available for Saturday’s clash with Oldham, but when they ran out of time to register him for that game he was given the weekend to think over the move.
Although the 21-year-old is still to make his debut for United he has plenty of first-team experience in the Nationwide League after loan spells with Darlington, Coventry City and Derby County, as well as playing 11 SPL games during a loan stay with Hibs.