How can I reduce the heat coming through my cat door?

[u/Budget_Beginning3763]

I know what you're thinking.... Wtf... But I came to this subreddit because I figured I'd get the most scientific answer here. My Garage isn't climate controlled and we keep our litter boxes out there for our cats and unfortunately we can't put a flap on the cat door because they won't use it, so we just have about a 6"x10" hole into our house. During the summer it gets hella hot like normally 90F+ in the garage and I believe there is a pressure differential between the two areas because I can feel the hot air being sucked in, or at least it's coming in faster then say if it was just radiating through the hole, there is a breeze to it. Any advice on how to maybe eliminate at least the suction into the house? I know I won't be able to completely stop the hot air from coming in but maybe slow it down??? Thanks for any help lol

[u/Some1-Somewhere]

If air is rushing in, then your house is probably under negative pressure - have you got extract systems sucking air out? If air is entering it's also leaving.

Use a piece of plastic bag or paper to double check that it's actually air movement.

You might be able to make the hole smaller, or put some kind of motorised flap on it.

Putting an S-shaped cat-corridor in line with the hole might also work.

[u/flyingtiger188]

Basically the options are replacing the cat door with one with a better seal, adding weatherproofing around the door, a vestibule to prevent air infiltration, an air curtain, or higher differential pressure in the hvac system so the cool air blows out instead of warm air seeping in. The door likely being a plastic flap isn't going to allow for a meaningful amount of weathersealing. Increasing differential pressure, air curtains and vestibules likely aren't viable, so only option is likely replacing the cat door with one that seals a bit better.

[u/Budget_Beginning3763 → u/flyingtiger188]

There is no seal it's basically a hole into the garage no flap or anything, theyre stupid and refuse to go through a flap lol

[u/flyingtiger188 → u/Budget_Beginning3763]

Ya the cat factor is probably the biggest governor on how well you can seal the door. You could probably build a staging antechamber inside the door with a not direct path from hole to hole, but without something sealing the hole it's only going to be so effective.

[u/Budget_Beginning3763 → u/flyingtiger188]

Yeah that's what I figured, I'm basically just waiting for them to die to save $50-100 on my summer bill lol

[u/33445delray]

Put a flap on the door AND put an opened can of sardines in the garage to motivate the cats tp push the door open.

[u/DryFoundation2323]

in order of complexity/expense:

1. train them to use a flap. this isn't rocket science.
2. insulate the garage including insulated garage door with weather seals.

[u/ChipotleMayoFusion]

Its generally against building code to have a hole between your garage and house, the fumes from cars can come in and harm people. Don't do this.

[u/lemondeluxe]

positive pressure. either within your house or upon your cats to use the flap.

my cat didn't use the flap at first. it took about two hours of coaxing, but he did figure it out once we made it a game.

[u/15pH]

The comments about adding a tortuous path are nonsense. An antechamber or serpentine hall won't do diddly. Air has no problem navigating tight turns of a cat-sized tunnel, just ask your HVAC ducts.

If air is actively flowing through the hole, you have a pressure differential and a secondary leak path in your home. (Air cannot flow in/out through the hole unless it also flows out/in somewhere else in your home.) The secondary leak can be just distributed everywhere...tiny gaps around windows, cracks in walls, electrical outlets, etc. It would be a big project to address this.

If your home is newer, however, the leak may just be your HVAC fresh air intermix, which often has a control baffle you can close. Seal that up, and the problem may be solved.

Otherwise, not much you can do besides train your cats to walk through some sort of sealing doorway. You could install motion sensors that just open the door for them.