If you would wear a couple more layers, you wouldn't need to turn on the heat.
If you layered up, you wouldn't need to use your heater so much.
ーIf you would wear a couple more layers, you wouldn't need to turn on the heat.
「もうあと数枚着込めば暖房つける必要ないよ。」
wear a couple more layers で「もう数枚着込む」
turn on the heat 「暖房を点ける」
ーIf you layered up, you wouldn't need to use your heater so much.
「着込めばそんなに暖房を使う必要はないよ。」
layer up で「着込む」とも言えます。
use one's heater 「暖房を使う」
ご参考まで！
カナダ 
