Chiasson, 25, had eight goals and 14 points this season, his second with the Senators. Calgary will be Chiasson's third team; Ottawa acquired Chiasson, Nicholas Paul, Alex Guptill and a second-round pick in the 2015 NHL Draft from the Dallas Stars in a trade for forwards Jason Spezza and Ludwig Karlsson on July 1, 2014.
A second-round pick (No. 38) of the Stars at the 2009 draft, Chiasson has 82 points in 239 NHL games split between Dallas and Ottawa.
Sieloff, 22, played one game and had one goal for the Flames in 2015-16. He spent the majority of the season with Stockton of the American Hockey League. He was a second-round pick (No. 42) of Calgary at the 2012 draft.
