What are some ways to cool an upstairs without a window AC?

A ductless mini-split is the only way to get that upstairs livable without pulling in your neighbors' bonfire smoke. Unlike window units or single-hose portable ACs, a mini-split doesn't have a direct air path from the outside. It uses a small refrigerant line to connect the indoor unit to an outdoor compressor, so you’re just recirculating and cooling the indoor air. It's more expensive than a window unit, but it solves the smoke detector issue permanently and is much quieter for the kids' rooms.

If you aren't ready for a full mini-split install, you need to look at why your central air isn't reaching the second floor. Check if you even have **return vents** upstairs. In 1912 houses, builders often only put returns on the main floor. If there’s nowhere for the hot air upstairs to go, the cold air from the basement or first floor can’t push its way up. You coud try installing an **in-line duct booster** fan in the supply line to the second floor, wich helps pull more air trough those old, narrow ducts.

Another trick is setting your thermostat fan to "On" instead of "Auto." This keeps the air moving 24/7. It won't magically drop the temp 13 degrees, but it helps blend the air so the upstairs isn't a stagnant pocket of heat. Just make sure your filter is clean, beacuse running it constantly will clog it up faster.

Be careful with portable units. Most cheap ones are single-hose, which acutally creates negative pressure and sucks outside air (and smoke) through every crack in your windows and doors to replace the air it's blowing out the exhaust. If you go portable, it absolutely has to be a **dual-hose** model or you’ll just be inviting the bonfire smoke inside even faster than a window unit does.

I had no idea single-hose units could actualy pull more smoke in. That sounds like exactly what happened to us last summer! Are the dual-hose models a lot bigger? We have pretty tight bedrooms upstairs and I'm worried about the footprint of a giant machine plus two hoses. On the mini-split side, is that something a DIYer can handle or do you have to hire a pro? I've seen some pre-charged kits online but I'm nervous about messing up the walls in an old house.

The DIY kits like MrCool are decent, but 1912 houses ussually have thick masonry or old-growth wood thatu2019ll put your drill to the test. If you go that route, get a helper; wrestling those pre-charged lines without kinking them is a two-person job.

Regarding the dual-hose units, they are defintely chunky. Youu2019re looking at a footprint of about 18"x16", plus you need another 10-12 inches of clearance behind them so the hoses don't kink. If the bedrooms are tiny, it's going to feel crowded. If youu2019re committed to no window units, a mini-split is the only way to get real capacity without losing all your floor space to a plastic monolith.

Have you checked your attic insulation lately? In those old 1910s builds, there's usally next to nothing up there, or just some ancient rockwool that's flattened to an inch. If your roof is baking, it doesn't matter how much cold air you pump upstairs. Also, try partially closing the vents on the first floor. It forces the blower to send more of that cold air to the second floor. Just don't close them all the way or you'll freeze the evaporator coil. Combining that with some heavy blackout curtains on the south-facing windows made a 5-degree difference in my old place.

definitly check your attic hatch seal. In those 1912 houses, if the hatch isn't weather-stripped, it creates a massive "stack effect." The hot air escaping into the attic literally sucks air from the lower floors and trough any window gaps, which is probaly why the smoke is getting pulled in so aggressively.

Also, look into honeycomb or cellular shades. If you have original single-pane glass, those windows are basically space heaters in the summer. Side-track shades can significantly cut the radiant heat load so your cooling system doesn't have to work nearly as hard. It's a low-tech fix that makes a huge difference in those "sweatbox" upstairs bedrooms.