Hey Ed, what is the most efficient way to connect a return duct to an air handler?

In this edition of "Hey Ed," Ed discusses the most efficient ways to connect a return duct to an air handler.

Hey Ed, what is the most efficient way to connect a return duct to an air handler? I like the way this question was originally asked because the word "efficient" is applicable here. The best way to bring air into the air handler is through the bottom. The next one is through the bottom and a side at the same time. Preferably the side that the motor itself does not exist on. Next is going to be coming in both sides. The idea of coming off the back of a furnace is not a thing at least that I’m aware of. And I’m simply going to say that you can get better airflow out of a furnace depending on where you tap it. And that’s the way I see it.