please do not place anything large so that warm air will circulate throughout the room
could you not put anything big in this room, so that the warm air circulates?
文章で丁寧に伝えるのであれば「please do not place anything large so that warm air will circulate throughout the room」と私なら書きますが、もし会話中に口頭で話すのであれば「could you not put anything big in this room, so that the warm air circulates?」という風に言います。
2文目はかなりくだけたカジュアルな言い方なので、もし目上の方などに会話で伝えるのであれば「can I ask you not to put anything big in this room, so that the warm air circulates?」と言い方を変えます。
"Don't put any large objects in the room so that warm air can permeate throughout the room."
"Don't put any large objects in the room so that warm air can permeate throughout the room."
"don't put ~" 「〜置かないで」
"any large objects" 「大きな物」
"in the room" 「部屋に」
"so that ~" 「〜ように」
"warm air" 「暖かい空気」
"can permeate throughout the room" 「部屋に行き渡る」
日本 
オーストラリア 
