All I can really say is to avoid the floor models, since they put the hot part of the conditioner inside your home, thus have to work a lot harder

See Technology Connections (Piped) for an informational video

Don’t do it at this time of year.

I know it’s a considerable cost increase and installation, but still way cheaper than upgrading your central A/C, and way more efficient, quiet, elegant than a window unit: add a mini-split to the room. I added a Mitsubishi to our hot office with tons of electronics and it’s one of the best home investments I made.

They’re mostly all made in one or two factories in China. Midea and another one.

When it comes time to replace the AC, consider getting one that’s reversible and runs as a heat pump. You don’t need to use it, but it shouldn’t cost much more and gives you flexibility.

Be aware that most window A/C units are power hogs. Expect to see a significant rise in your power bill. It might be cheaper to have your home A/C unit serviced instead. Could it be low on freon? Would it benefit from having the coils cleaned?

Make sure you buy one with enough cooling power to cool the room it’s in. If it’s a small bedroom you’ll want 5,000-8,000 BTU and if it’s a larger area like a living room you’ll probably want 12,000-14,000 BTU.
I just put a 12,000 BTU unit in my living room because it’s open to the kitchen and it’s about 550ft².
A good rule of thumb is 20 BTU per Ft², so my 550ft² living room/kitchen area would require at least 11,000 BTU.

What size is your central AC (usually measured in “tons”) and what’s the total area of the space you’re trying to condition? Single story or multiple stories?

Just don’t get a portable unit. They suck and are just a waste of money most of the times.

These are portables if you’re unfamiliar.

So you have three options, I’m going to break them down just because I think comparing all three is helpful for long term planning, but skip to the end for advice on a specific window unit.

1. Upgrading your central AC and/ or it’s duct work.

• Cons:
  • 💰 Expensive - central units are expensive
  • 🧑‍🔬 Installation - these require professional installation from certified technicians.
  • 🪚 Duct work - if it requires duct work changes then modifying the house to accomodate is a whole nother headache.
• Pros:
  • 😸 Efficiency / long term electricity savings - a newer central AC will be more efficient for cooling the whole house down. They typically have SEER ratings in the 15-18 range.
  • 🔇 Noise - you might hear them start up, but most rooms of the house hear nothing from the vents.
  • ☀️ Light - they don’t impact natural window light at all
  • 🌡️Heat Pump - newer units are typically heat pumps that can efficiently and economically heat your house in the winter or at least shoulder seasons.

2. Getting a window unit.

• Cons:
  • 🌥️ Light Reduction - Blocks some of the window
  • 😿 Efficiency - Typically* lower efficiency ratings
  • 🔊 Noise - You’ll inherently have more noise from a fan blowing cold air into the room (compared to a central vent), and because the outdoor compressor unit is so close, most window units* also have quite a lot of sound coming from the outdoor portion.
  • 🥶 AC Only - Typically no heat pump capabilities.
• Pros:
  • 🫰Cheap - Lowest up front cost
  • 👨‍🔧 Easy installation - DIY
  • ↪️ Portability - Can be removed or sold later if it’s not needed.
  • 😸Efficiency? - while central AC units are typically more efficient on a per unit of cooling basis, if your window AC is in the right room it can actually be more efficient overall. i.e. if it’s in your bedroom, even if the window unit is less efficient than a central one, you might use less electricity just cooling your bedroom and letting the rest of the house get warmer.

3. Mini - Split Systems - install a compressor outside your house and a blower unit in a specific room or hallway

• Cons

  • 💲💲Expensive - these are more expensive than window units up front by quite a bit.

  • 🙇/👩‍🔧 Installation - Potential DIY - while they do sell DIY mini-split systems that don’t require professional installation, you’ll be limited by the length of pipe / hoses they provide, so need a suitable spot for your compressor unit. Otherwise you’ll need a pro to install it.

  • 🔉Noise - since the compressor is outside and separated by a wall you shouldn’t hear it if it’s mounted properly, but you do still have an indoor blower unit. It’ll be quieter than a window unit but louder than a vent.

• Pros
  • ☀️ Light - no light blocking
  • 🐸 Efficiency - Mini splits often have efficiency ratings that meet or exceed central units, on top of the fact that they can be used to just cool the needed room.
  • 🌡️Heat Pump - these are also typically heat pumps.

If it were me personally, and I owned the house, and I was worried about cooling my bedroom, and I had the money and somewhere to mount the compressor, I would buy a DIY mini split system. I will always want my bedroom to be cold for sleeping and the rest of the house doesn’t need to be that cold (and vice versa in winter since they’re heat pumps that go both ways). The only real downsides are the very light fan noise from the blower unit, and the upfront cost, though that can potentially be mitigated if you live in a jurisdiction that offers some type of home retrofit or heat pump grant (worth checking!).

That being said there’s a bunch of caveats and criteria there that I personally didn’t meet, so I bought one of those Midea U shaped units that everyone talks about and am honestly very happy. There was a massive recall recently, but they’re adding drains to fix the issue, and these units otherwise are way better than most other window units, though they only work with windows that slide up and down vertically.

*But unlike most other window ACs, the U shaped units have the window sit between the outdoor unit and the indoor unit which blocks most of the noise from the compressor, lets more natural light come in, and doesn’t require blocking the sides. They’re also very efficient with a CEER rating of 15.

Even despite the recall they’re still what I’d personally recommend, you might be able to find one second hand.

Also note that I don’t consider a portable air conditioner an option. They’re terrible.

I was in the same situation as you at my last house. Central AC was added to a 100 year old house but it was never enough. I got new windows put in, and that helped, but it still got to hot in the summer.

We got this U Shaped Midea window unit and that did the trick: https://www.midea.com/us/store/cooling-and-heating/window-air-conditioners/u-shaped-air-conditioner-ultra-quiet.MAW08U1QWT

It’s better than a standard window unit because you can close the window nearly all the way, unlike standard window units that rely on those crappy plastic accordion things.

Best of luck.

Not what you asked, but you might check that:

• The central AC doesn’t need to be recharged. If it has leaked coolant and is low, it will drop in effectiveness.

• Or, even more simply, that the air filters don’t need to be replaced.

• You can’t improve insulation. Doing so is a one-off cost, as opposed to the ongoing cost of throwing more air conditioning muscle at the problem. Weatherstrip leaks, replace any single-pane windows with double-pane, etc.