The Leeds born striker has slipped further down the Boro pecking order after the arrival of Michael Ricketts and Malcolm Christie.
With his first team chances limited already this season the 28 year old may have to look for a permanent move in the summer.
Whelan joins ex Boro full back Curtis Fleming who is club captain at Selhurst Park.
Meanwhile young full back Brian Close has joined Chesterfield on a month's loan.
With his first team chances limited already this season the 28 year old may have to look for a permanent move in the summer.
Whelan joins ex Boro full back Curtis Fleming who is club captain at Selhurst Park.
Meanwhile young full back Brian Close has joined Chesterfield on a month's loan.