上联楼下春风徐徐，下联楼上玉门关外，横批暖气管道走向

https://byrdheatingandair.com/articles/how-to-achieve-good-ductwork-design-for-your-home

 

https://www.hometalk.com/44158822/q-how-do-i-improve-heat-flow-to-my-upstairs