Why is my portable AC making the rest of the house feel like a sauna?

The draft you're feeling under the door is caused by **negative pressure**, which is the fundamental flaw of any single-hose portable air conditioner. Because that single hose is constantly blasting air out the window, your office becomes a low-pressure zone and has to pull replacement air from somewhere. Usually, that means sucking in hot air from the hallway or trough gaps in the floorboards. You're effectively trying to cool the entire house through your office door. These units are really meant for supplemental cooling in a room that's already mostly conditioned. If your central air is struggling to keep one room at 72 but the rest of the house is 74, a single hose works fine because the replacement air being sucked in is already relatively cool. But if your office starts at 85 degrees, you're fighting a losing battle against physics. Every cubic foot of air the machine cools and exhausts is immediatly replaced by a cubic foot of unconditioned air from the rest of the house.

A **dual-hose** setup fixes this by using a completely separate air loop for the condenser. One hose sucks in outside air, passes it over the hot coils, and the second hose spits it back outside. This means the air inside your office stays inside your office. It just gets pulled into the front of the AC, cooled, and blown back at you without creating any negative pressure. No more drafts under the door and no more sucking in hallway heat.

They can be a bit harder to find in big box stores, but brands like Whynter or the Midea Duo are the standard recommendations for a reason. If you switch to a dual-hose model, you'll notice the room drops in temperature way faster because you aren't constantly diluting your cold air with unconditioned air. Just make sure the window kit is sealed tight with some **weather stripping** or foam tape, otherwise, you'll still get some heat leakage around the edges of the hoses.

While the previous poster correctly identified the pressure differential, users frequently overlook the significant thermal infiltration occurring via the uninsulated corrugated plastic exhaust hose, wich essentially acts as a massive radiator emitting infrared heat back into the space you are attempting to cool. I actually took a thermal imaging camera to my old unit last summer and recorded surface temperatures exceeding 125 degrees on that hose, which significantly negates a portion of the evaporator's net cooling capacity. If you stick with a single-hose, try wrapping the exhaust in an insulated sleeve to mitigate that specific radiant heat gain, though the dual-hose remains the mathematically superior choice for thermal efficiency.

Have you ruled out basic solar gain through the window glass? 120 square feet is tiny, and if you have a big unshaded window, that's going to dump more heat into the room than any AC can reasonably keep up with. Also, check where your unit is actually positioned. If it's tucked in a corner with no clearance, the internal thermostat might be cycling off way too early because it's sitting in its own cold pocket, even if the rest of the room is still 80 degrees. Is the hallway hot because of the draft, or is the unit's body itself just radiating heat from the compressor?

I had the same vacuum issue untill I pulled the trigger on the LG LP1419IVSM Dual Inverter. It’s a beast for small offices because it acutally throttles down once it hits the target temp instead of just clunking on and off. That dual-hose setup is the only way you'll stop sucking in the 85-degree hallway air. It’s pricey, but it's the quietest unit I've ever owned. If you’re tired of the draft, just get the LG and call it a day.