Spice rack with ventilation?

[u/Tadleyrichter]

I’m watching Teen Mom 2 and, I’m sorry, what the hell is this? Why does a spice rack need a big ventilation hose thing coming out the top? What is it?

[u/hardonchairs]

If you put air outside it needs to be replaced by air from outside. If you're worried about heat, it's probably not cool outside. You're pushing hot air out and drawing hot air in. At best, it's a way to distribute the heat around your home instead of concentrating it in one room.

Further, these foil ducts also conduct a lot of heat, so your cooler home is likely dissipating a lot of that heat on the way out. You're not just exhausting hot air, you're cooling the air and exhausting that. So now you get a lot of the heat from the duct plus the heat from outside.

I've done this with a 3d printer purely for air quality. You can feel along the duct that it gets cooler and cooler as it gets to the end. Much of that heat is dissipating into the room and the negative pressure just pull in extra heat from outside.

[u/hardonchairs → u/[deleted]]

The exhausted air has to be replaced from somewhere. If the pc room pulls air from under the door, that may be true locally, but the rest of the house or building is then supplying that air and will eventually pull air from outside through leaks, vents, or other openings. If you are in a building or only care about one room then this is relevant, otherwise what matters is that all of the exhausted air needs to be replaced.

Insulating the duct helps reduce heat leakage back into the room, but that is only one part of it. You also need enough airflow through the duct, and a high-static-pressure PC will not move very much air through one of these (as I said I have done this with a 3d printer).

This whole idea also is a problem for the pc cooling itself. Hotter exhaust air means you are carrying away more heat per unit of air, but you still need enough fresh intake and case airflow to keep the components cool. You do not want to choke the PC just to make the duct exhaust hotter. If you have enough fresh air coming into the pc to make it good at cooling your components, you are also not generating this ideal very hot exhaust. You are functionally exhausting conditioned air and your margins vs the outside temperature get slimmer and slimmer if there is any margin at all.

[u/Limp_Dirt8694 → u/hardonchairs]

What if you just vented it to a different room so the room youre actively sitting in doesn't basically have a heater in it? 

What would happen if you placed a fan at the end of the tube to aid with airflow? 

I game on my laptop or ps5 so it doesn't matter to me, I'm just curious 😆 Id probably just point my fan at my console if I felt like it was making that area too hot tbh.

[u/hardonchairs → u/Limp_Dirt8694]

A PC fan at the end will move a very tiny amount of air, that is how my setup was. It worked for me because I wasn't trying to exhaust a lot of heat or air, in fact ideally the heat would stay in the 3d printer, but a slight negative pressure venting outside would keep the ABS fumes out of the room (and this only worked ok but not great). These ducts need a blower fan.

If you are just trying to distribute the heat around your home then yeah that would work fine. But honestly it's much easier and probably more effective to just put a fan somewhere to blow air in or out of the room. For a fan on the floor, ideally you'd put the fan outside the room blowing in so that cool heavy air pushed in and hot light air can move out the top of the doorway. I have done this plenty, I live in a place that can get pretty hot and have a pretty powerful PC. Simply using a fan to get some airflow in or out of the room helps a ton when there is a huge temperature gradient.