Optimize Your AC

New York Times

17-07-2025

CHRISTINE: I would love for you to explain, in the simplest terms, how AC works.
THOM: Sure, so there's a little fairy inside the box. Okay.
CHRISTINE: I'm Christine Cyr Clisset.
CAIRA: I'm Caira Blackwell.
ROSIE: I'm Rosie Guerin, and you're listening to The Wirecutter Show .
CHRISTINE: This episode is called Optimize Your AC
ROSIE: Hello.
CAIRA: Hi.
CHRISTINE: Hello.
ROSIE: Welcome to another episode of The Wirecutter Show , Caira and Christine.
CHRISTINE: Oh. Well hello, Rosie.
CAIRA: Why are we talking like this?
ROSIE: Today is a serious topic.
CHRISTINE: It's hot.
ROSIE: It is hot.
CHRISTINE: It's so hot.
ROSIE: It's so hot. And actually, let's get serious about talking about cooling off your house. This is the time of year I have to start prodding my super to install our AC window units, because it is so hot.
CAIRA: My super never offered to uninstall and install my AC units.
ROSIE: I think it's a liability thing, which honestly I'm glad, because I never felt confident about throwing those units in and slamming the window down.
CAIRA: Yeah.
CHRISTINE: My husband does it, and I just leave.
ROSIE: I don't have one of those.
CHRISTINE: I'm like, "I'll see you later."
ROSIE: I don't have-
CHRISTINE: Oh, well yeah.
ROSIE: I have window units, but not a husband.
CHRISTINE: But you have a super. Well, I grew up without AC. I'm from the Pacific Northwest and a lot of people in the Pacific Northwest do not have AC. And that is becoming a bigger issue, because it's getting hotter. A lot of people don't have windows that will fit a window AC, and a lot of people don't have central AC. So it can be really tricky.
ROSIE: I remember in the dead of summer, having to rely on the window fans that my dad would install in my bedroom.
CHRISTINE: Oh, yeah.
ROSIE: This was before we had central air, and it was like, "Yeah, that was what we had."
CHRISTINE: Yeah. We have a lot of coverage on our site around air conditioners. We have guides to window units, and portable units, and split units, which we're going to talk about in a little bit. But we also have a lot of coverage around how to keep your home cool even if you do not have AC, and there's a lot of different strategies you can use.
CAIRA: Yeah. So today on the show we're going to talk with staff writer Thom Dunn who reviews all kinds of air conditioning units. He's going to walk us through how window and portable units have become a lot better over the past decade, and he'll also share some strategies that anybody can use regardless of the type of AC they're using or if they have it to begin with to keep their home cooler.
CHRISTINE: And we're also going to talk with senior staff writer Liam McCabe about heat pumps, which can replace a traditional AC system. These can be a beneficial investment if you're a homeowner considering an upgrade to your heating and cooling system.
ROSIE:
And a bit later, we'll tell you about a recent recall of Wirecutter's favorite window AC, the Midea U. Christine will lay out how to figure out if you have a recalled model at home and what you can do about it. We'll be back after a break with everything you need to know about AC's with Thom Dunn. Stick around.
CAIRA: Welcome back. With us now is Thom Dunn, who is a staff writer who focuses on heating, cooling and humidification gear. He's tested over 100 ACs and fans for Wirecutter since 2017. For our window AC guide alone, Thom has tested over four dozen AC units, and he's manually installing them in his home in the muggy Boston Heat himself.
CHRISTINE: Welcome to the show.
THOM: Thank you for having me.
ROSIE: God's work, Thom, God's work. Thom, how are you testing all of these window AC units in your home? Is it like you have 48 windows and 48 AC units?
THOM: The first year I tested this, we actually lived in Ithaca, New York, and I had an extra guest room that had three hung windows in it. That's the kind that vertically slides up and down. And I think my neighbors thought I was a psychopath, because I had three ACs stacked in all the windows of one bedroom. At our home now, I have exactly one hung window. So my spring is a nice frantic ballet as I wait for the weather. And I have all the ACs ready to go to pop them in there, and I take my first round of tests as quickly as possible as the weather permits in April and May. Once I can identify the best of the ACs I have, I can start to really dig in deeper on various metrics and various experiences that I like to look for as I test them to figure out which ones are the best.
ROSIE: What are the metrics?
THOM: Generally speaking, most window air conditioners, the specs that you get on the box, on the Energy Star label or whatever are usually pretty accurate. They tell you what the energy efficiency is, they give you an approximate power level and room size. That's usually all pretty accurate because Energy Star tracks that stuff and that's great. So what I try to do is I measure the noise level with the fan, and the different fan settings with the different compressor settings. I don't just measure the volume. I have a spectrometer on my phone so I can see what kind of frequencies are spiking here and there. So I'm like, "Oh, that one, I was just testing one right before this call, and I noticed that when the compressor was on it added 10 decibels just on the low end, and I had these really annoying spikes."
So I could look at the spectrometer and be like, "Oh yeah, that's that whining thing in my ear that's making me want to hit myself in the head." That's what that sound is. And I take those notes. And while I do that, I also, I have it plugged into an energy consumption monitor so I can track how much power it's using.
ROSIE: So you're actually measuring the energy output, you're measuring noise level. What else makes it into the metric?
THOM: So then I also have a few monitors set up around my office so I can track over the course of several hours how the temperature and the humidity changes. The general testing process is that I will let them run for usually about two hours, and I leave the monitors, one about three feet away and one about six feet away on a diagonal and I track all the changes in temperature and humidity. And I go back and look at that and be like, "How well is it moving air around the room? How quickly did it cool the room?"
And the whole time I do that, I am sitting in the room taking notes anyway, seeing how comfortable... Maybe I thought a fan was loud at first. But then when you're sitting in the room you go, "Yeah, no, that's okay." Sometimes you sit in the room and you think it's a great air conditioner, and then you go, "Why am I so uncomfortable right now?" And then you start digging in more to figure out what about this one is making me feel miserable?
ROSIE: Is user experience part of the testing as well, just in terms of how you get this in and out of a window if it's a window unit, or how you have to maintain it if you need to maintain it at all?
THOM: User experience is definitely a factor. It is a funny catch with ACs, because I think as a general rule we can expect that they're all miserable to deal with. They're all cumbersome, they're all heavy. None of them are fun to lug into a window and pull the top window down quickly to hold it in place. Some of them are worse than others, and some of them are better than others. Our long-running, what's our budget pick now, is this Frigidaire model. I look at that as the most perfectly mediocre air conditioner you could find.
ROSIE: It's the one to beat.
THOM: Yeah, that's our budget pick at the moment. We've recommended it for years, because it's perfectly fine. And that's the metric point I use for how easy is this one to put together and install, or how easy are the controls here?
CHRISTINE: Thom, I would love for you to explain in the simplest terms how AC works, because it's just like magic. There's cool air that comes in, it's great, but I actually don't know what's happening inside the machine. So can you just explain how AC works?
THOM: Sure, so there's a little fairy inside the box. Okay. So you AC, whether it's... Whatever kind it is, it's basically sucking in the air from the house, and then it drags it over a coil of refrigerant, a chemical that gets really cold. As it drags the air over the cold coil, that cold coil pulls out some of the heat particles and some of the moisture, like when a cold cup sweats in the summer.
So it collects the heat and the moisture on the cold coil, and there's this whole refrigerant compression and then condensing process. But the TLDR version is that there's a fan that then takes the moisture and the hot air and blows it out the back. And then another fan that takes whatever's left and throws it back into the room.
CHRISTINE: So it's like this cycle. Pulling in the hot air from inside your home, cooling it off and then spitting out the cooled air back into your room and all the hot stuff back outside.
THOM: Yeah, that's right.
CHRISTINE: Okay. And it doesn't matter what type of AC you have, whether it's a window unit, a portable unit, central air, any kind of AC works in the same way.
THOM: Correct.
ROSIE: What is the difference between a window unit and a portable unit?
THOM: An air conditioner in general is whatever conditions your air. And that could be your central HVAC system, it could be a heat pump, it could be a window or a portable air conditioner. Window units require a hung window. The hung window helps to keep the window AC in place, so that's a requirement. Half the unit is in the house, half the unit is outside, so you get the good stuff on the inside and the bad stuff all goes outside.
Not everyone has a hung window though. There are all kinds of different windows, or for various reasons you might not be able to put a window unit in your hung window even if you have one.
CAIRA: But my house upstate has windows that open left to right.
THOM: Those are not hung. In that case, you would need to use a portable air conditioner. And portable air conditioners are a bit more adaptable. That's the good thing about them. They often come with these window kits that can fit into all kinds of different other window settings. You can really make them work in a lot of different scenarios, including in a hung window.
The trick with the portable AC though is that they're not as efficient as a window unit. First of all, you have a big R2D2 looking thing that has to sit there in your room and it takes up space. There's also the fact that it has these clunky octopus tentacle hoses that have to pump the air out the window. So you have to exhaust some of the air, and by basic physics of mechanics, when all the hardware inside the air conditioner is working, it produces some heat.
So the portable AC is now sitting in your room producing heat, radiating heat out of itself, and then you're also trying to cool the room. But by trying to cool the room, AC itself is working against itself by heating up. And then it also has to push the hot air that it's removing from the room out of the tubes and out the window. But even then, you're starting to lose some of the hot air as it moves out of those tubes and that it leaks into your room.
So the portable AC is kind of fighting against itself. Whereas when you have a window air conditioner right in the window there, it's pushing the cold air into the room and it's pushing all the hot air and mechanical heat radiation out the back outside.
CAIRA: Most of the window and portable units that Wirecutter recommends, that you recommend, Thom, use something called an inverter compressor. You see that word all over the guides. What is that, and why is it important, and how does it actually make an AC more efficient?
THOM: The compressor is the part of your air conditioner that when you turn it on and you hear it in the background go, that's the compressor. What that does is it helps transform the cold refrigerant from a liquid into a high pressure gas, which you can then expel outside along with all the other hot air it collects.
Historically, these compressors had two modes. They were on or off, zero or 100%, and that's why it made that annoying noise. A lot of people complain about their older air conditioners that when they start you're like, "Oh, it's on. Okay, I hear it." Because there's the fan, and then there's just that low rumble and it just kicks on and it's annoying.
An inverter compressor works more like the gas pedal on a car. You can push it all the way and really throttle up, or you can slowly ease on the gas and you don't ever have to stop the car completely. It's energy efficient, and it's much, much, much more pleasant.
CHRISTINE: And it's more energy efficient, Thom. Is that because if you're fully stopped and then to restart and get up to speed, whether you're in a car or whether you're getting up to speed and the machine is running, that takes more energy than just running at a low level all the time?
THOM: Exactly. It takes a lot more energy to start and get into motion, whereas if you were already in motion, you'd keep going.
ROSIE: If I have an older AC unit without an inverter compressor, it sounds like I should consider upgrading it.
THOM: Yes and no. Generally speaking, I'm against upgrading your air conditioner unless you absolutely have to. Maybe that's just my larger environmental concerns. You have these chemical refrigerants which are not good for the planet. You don't want to dump those into the town dump. You have all this metal and styrofoam. But if your machine is hurting, if it's not cooling the air and you need a new air conditioner, I would absolutely recommend looking for an inverter model whenever possible.
CAIRA: Well, I remember in my first apartment in New York, it was a three bed, it was tiny. But for whatever reason, the only AC unit that my dad thought to give me was 100 pounds, huge. We carried it up six flights of stairs, and we decided to put it in the living room. It overly cooled the living room, and all of the bedrooms stayed hot. And I just wonder what size AC unit should I have gotten for that apartment to make it a livable space? So I know that AC units come in all these different sizes, but how do you know if you're getting the right size?
THOM: Right. Well first of all, in that situation... So your living room was cool, right?
CAIRA: Yeah, it was freezing. But the bedrooms were all steaming.
THOM: Okay. The trick there is you should have left the doors open during the day and had some fans running.
CAIRA: Oh.
THOM: That could have helped a lot. I know you have roommates, you don't want to-
CAIRA: We all just basically live in the one room. It's just all the doors are open.
THOM: Right. I do understand that, and that puts you in a weird spot. So that way it wouldn't be miserably cold in the living room and it would spread that air around. But on a larger scale, the answer to that question, ACs are typically sized in BTU, British thermal units. I don't know why.
CAIRA: The Brits.
ROSIE: Colonialism.
THOM: Yeah, I don't know who in Britain invented this necessarily, but it is the amount of energy needed to heat one pound of water by one degree. Most of these air conditioners that you'll find today give a room size recommendation. So we typically test using 8,000 BTU models. 8,000 BTUs are usually recommended for rooms of 250 to three 50 square feet. I'm guessing, Kyra, that your dad got you a 12,000 BTU AC for that room.
ROSIE: It was huge, Thom.
THOM: I'm going to guess, which is usually for 450 or 500 square feet and up.
CAIRA: Our entire apartment was probably 300 square feet total.
THOM: Right, you lived in New York, I get it.
It can be tempting to be like, "Oh, cool, this one's bigger and colder." But that is a temptation you should resist. Last year, I started wondering about this because they were so much cheaper, especially I found that Costco always had sales on huge versions of our picks. And what I found, I did some tests last year. I was testing one of the 12,000 BTU units in my office space. I was so miserable. I went and grabbed a hoodie. And I was sitting here and I was like, "Okay, it's July, it is 85 degrees outside and I just went to get a hoodie."
My office felt like I was in Ireland. I just felt damp. And that's because the larger ACs can do a worse job of removing the moisture from the air. So they will do a fantastic freaking job of just cooling your room really fast. Your room goes from 80 to 60 and you're comfortable. Great. You think, except the humidity in the room has barely changed at that point, and now you are feeling clammy, and you are feeling damp and it sucks.
CHRISTINE: So basically, Thom, to keep your home at a comfortable temperature, you should get an AC unit appropriately sized for your space. And if you're finding that you're not feeling comfortable in an air conditioned room, it may be a humidity issue?
THOM: Yeah, the ACs direct some of their energy to cooling and some of it to moisture removal, and the larger ones just can't remove as much of the moisture as quickly. I will add, a lot of the air conditioners come with built-in dehumidifier modes, and a lot of them also have some sort of auto setting. And for most people actually, especially if you have an inverter model, I actually recommend just leaving your AC pretty much all summer on the auto setting. Because that way there are some days where it's not that hot but it's really humid, and the AC will flip over to dehumidify mode and actually cool you down.
ROSIE: So to that end, Thom, the $100 million question, do we need to be turning our AC off when we leave the house or the apartment to save energy?
THOM: No. Not necessarily. As far as your own energy bill use goes, you can actually save money by leaving your air conditioner on. I did a piece last year. I set up air conditioners in three units stacked in my building across the course of several days during a heat wave. And for some of the days I turned the ACs off during work hours, air quotes, and then turned them back on around four PM before people got home from work. And then the other days I left them running all day at a higher temperature.
And when I left it running all day, it used a lot less energy and it was ultimately more comfortable. So if you really want to save the energy and be more comfortable, you want to just turn your AC up a little bit when you're not home.
ROSIE: That's very surprising.
CAIRA: Hot take.
CHRISTINE: Yeah.
ROSIE: And a very hot take.
THOM: I'm going to get so many angry emails again. And you know what? I stand by it.
CHRISTINE: So for folks listening at home, if you're in the market for either a window unit or a portable unit, which is not as great as a window unit, you might want to think about an inverter model that has an inverter compressor. And all of us should be thinking about just keeping our ACs on instead of turning them off. It can be more energy efficient that way, especially if you're using an inverter compressor.
CAIRA: But also get an AC unit that fits the size of your room.
CHRISTINE: Exactly.
THOM: Bigger is not always better, folks.
CHRISTINE: Okay, so we've covered the basics of portable and window AC units. But for some people listening at home, you may not have a window unit or a portable unit. Maybe you have central air, which is when your heating and cooling runs through duct work in the walls or the ceiling. Or maybe you have ductless mini splits, and those are the units that are mounted onto a wall, or a ceiling or the floor that also serve as both a heater and an AC unit.
So if you're a homeowner, you may end up coming to a cross in the road where you have to decide whether you're going to upgrade your AC and your heating. And oftentimes today, that means you're going to be talking about a heat pump. So we're going to actually take a break right now, and when we're back, we're going to bring on another one of our colleagues, Liam McCabe, to talk to us about heat pumps and why someone might want to consider one if they're about to upgrade their HVAC system.
And then Thom, we're going to have you back, and we're going to talk a little bit more about what anyone can do to keep their home cooler. Whether they are using AC, or whether you don't have AC and you're just facing a heat wave and you need to figure out how to keep your home cool. We'll be right back.
CAIRA: Welcome back. This episode is all about keeping your home cool this summer. Earlier, we talked with Thom Dunn about what you should know about window and portable AC units, which are a great solution for people who don't have central air or split units. We're going to come back to Thom in a bit. But right now, we're going to focus briefly on what homeowners should consider if they're thinking about upgrading their cooling system.
CHRISTINE: That's right. And for that, we're going to welcome another Wirecutter colleague, senior staff writer Liam McCabe, to tell us about heat pumps, what they are and why you might want to consider one if you have a split unit or central air.
CAIRA: Liam, welcome to the show.
LIAM: Hi, Caira.
CAIRA: Hi. So you've written about heating and cooling for Wirecutter for years, and you also worked briefly at EnergySage, which is a company that helps connect heat pumps and solar panels with homeowners, right?
LIAM: Yep, that's right.
CAIRA: And you've also written a lot about heat pumps and home electrification. So can you tell me what exactly a heat pump is and how does it relate to air conditioning?
LIAM: So a heat pump, they've actually been around for decades, but the tech improved a lot recently. They're all electric, so they don't use gas or oil, and it's super energy efficient for heating, so there's a lot of excitement from a clean energy perspective. If your house already has duct work in it, it's already there, you can... Instead of having a furnace and an air conditioner hooked up, you can just put a heat pump on there the same way that you would hook up an air conditioner. So there's a box outside your house. When we're talking about air conditioners, that's called condenser, but everyone just knows it is the big box outside the house.
CAIRA: Oh, with the fan?
LIAM: With the fan, yeah.
CAIRA: Okay.
LIAM: Yeah, yeah. And then there's an interior part, the coil, and that's attached to your duct work. And a fan blows across it. And if the coil's cold, you're going to get cold air through your ducts. That's air conditioning. If it's hot when the furnace is running or when the heat pump is in heating mode, it blows warm air through your ducts. That's where you get your heating.
So with a ductless system, it's the same principle. You still have the outdoor box, but instead of one coil hooked up to the central duct work in your house, you have a bunch of mini coils all around your house in every room that you want to heat and cool. And it's all contained in that wall wart, as people call it, or the indoor unit as it's more technically referred to. And it's the same process happening, it's just in a slightly different format.
CAIRA: That sounds very similar to the way that Thom just described how AC units work, except heat pumps can do heating and cooling, whereas ACs can only do cooling.
LIAM: Right. So in cooling mode, a heat pump works exactly the same way as an air conditioner. There is actually no difference at all. People think of it like it's actually bringing cold air into your house. What it's really doing is absorbing the heat into the cold coil, and then sending it outside through that box that's outside.
In heating mode, it works backwards. There's a coil outside the house too. That's soaking up the heat from the ambient air, and even when it's really cold outside, there's actually heat out there. The coil will soak up that heat, move it inside to the indoor coil, and then that will be hot or warm at least, and the fan will blow across the warm coil and move the heat throughout your house.
CAIRA: I'm pretty personally invested in this, because I bought an old, rickety wooden cabin in upstate New York, and it's got no heating or cooling system that's centralized. It's got this gigantic propane heater, and no AC at all. So I looked into getting a heat pump for the house, and I was just floored by how expensive these can be, tens of thousands of dollars. So why switch to a heat pump if it's that expensive?
LIAM: So any kind of HVAC upgrade, a central system like a furnace or an air conditioner, especially if your home doesn't already have it, is going to be five figures. It's a similar level of expense as what you got for the mini split quote. It's a huge comfort upgrade over window ACs. A mini split is usually the easiest way to get central or built-in AC to your house if your home doesn't already have it, and it's just a huge quality of life improvement. It's much quieter, your windows aren't blocked, you don't have to move anything. The cheap heat you get from them is almost like a bonus, and it looks better. Not everyone loves the wall mount style, some people call them wall warts. But they're ...
CAIRA: They don't look that bad.
LIAM: No. And some manufacturers make some that look a little better. LG has one that looks like a picture frame. And then there's different styles. You can have them floor mounted, you can put them in the ceiling. So there's a lot of different options.
CAIRA: So it sounds like it might be an upfront cost, but it'll pay itself back in the long run. And also, it's just a luxury aesthetic upgrade.
LIAM: Yeah, so there is some payback. And aside from the money, you have to think about paying yourself back in terms of comfort. They usually work better also than the window ACs do, though that's changed a little bit. And yeah, it's a lifestyle upgrade in a way, just not having to deal with the hassle of the window units.
CAIRA: So what do you think one thing people considering getting a heat pump don't know that they really should?
LIAM: I think the trickiest part is the installation. We know the technology works really well when it's installed correctly, but it's hard to find someone who actually knows how to do it well. I did some reporting on this depending on who I talked to. They thought it was anywhere from 30% to 50% of heat pumps are installed so badly that it really has an effect on the comfort and the cost that you can expect on your utility bills.
CAIRA: Yikes.
LIAM: Yeah, and probably more than that are subpar compared to what they could be. But 30% to 50%, you're probably going to notice a problem. It's just not living up to the potential they have for comfort and energy savings. And sometimes the technology takes the blame, but it's usually because the installer didn't set things up correctly.
CAIRA: Luckily, you wrote a piece about how to find a good heat pump installer so people can refer to your guide if they really want to know all the details.
LIAM: Yeah, I've been told it scares people as much as it helps them. But I think it's better to be informed rather than going in without any background. So yeah, the story's up on Wirecutter and hopefully people find it helpful.
CAIRA: Can you tell me how people are paying for this, just assuming that you don't have five figures just sitting around in the bank?
LIAM: Sure, yeah. Heat pumps are often incentivized through rebates or tax credits. There is currently, for now, a $2,000 federal tax credit. If you get a system installed that meets all the requirements for efficiency, it's a fraction of the overall cost but it's still useful. And then some states or local utility companies have their own rebate programs. You have to work with your installer, usually there's some paperwork to do. But they can be pretty big. In Massachusetts, we've had one that will give you $10,000 back off the cost of the installation.
CAIRA: Wow.
LIAM: Yeah. I also found that it probably raised the price of installation by $7,000 or so.
CAIRA: No.
LIAM: Yeah. Some of the money goes into your pocket, but a lot of it goes into the pockets of the installers, and that's another topic for another time, I guess.
CAIRA: You got to spend money to make money. Or in this case, spend money so somebody else can make money.
LIAM: That's one way to think about it, yeah. A lot of the areas that have incentives for heat pumps also have these really low interest or 0% loan programs. It's another way to try to encourage people to adopt this technology.
CAIRA: All right, well thank you so much, Liam.
LIAM: Thanks, Caira.
CHRISTINE: All right, we are back with Thom Dunn to talk about some of the universal tips that anyone can use to keep their home cooler this summer. Thom, what are some of your basic strategies that anyone could use, whether they're using AC or not, to keep their home cooler this summer?
THOM: If you want to keep your home comfortable, honestly, all year round, weatherization is so key. You can get weatherizing strips you can line around your windows for example, or under your door. And that can make a humongous difference by keeping the outdoors air and the indoors air separate. You can honestly, a lot of times tell, if you just put your hand near the window or near the door, and there's sometimes gaps around plumbing or if you have air conditioning, or any pipes leading out of your home. Any of those little kinds of tiny cracks, you can very, very easily fill in with weather strips or with caulk. That will make probably the biggest difference.
Especially during the summer, you can also consider the way you're using shades, the way sunlight is getting into your room. When the sun gets into your house, it's going to get hotter, and sometimes that's awesome, especially in winter, but sometimes it's going to heat your house up and make it harder for you to work. So just close the blinds. And it feels sometimes silly to close the blinds when it's a beautiful sunny day outside. But when it's a beautiful sunny day outside and the sun is boiling you at 95 degrees, you want to keep that far away from you.
CHRISTINE: And Thom, there are certain shades that are more effective at blocking out heat from outside. I think that we have a piece on the site that talks about cellular shades.
THOM: Yes. I was grasping for the word there, but thank you. It was that cellular shades are a fantastic way to keep the heat on the outside.
CAIRA: Well what's a cellular shade?
CHRISTINE: They almost look like two shades that are glued together, and they're like a fan almost.
CAIRA: Oh, yeah. Yeah, yeah, yeah.
CHRISTINE: Yeah, yeah. And they create an air pocket that helps insulate.
THOM: Yeah, cellular shade sounds way fancier. And you open the box, you're like, "Cool, it's some crinkly paper."
CAIRA: It's important, I mean.
THOM: But it does a great job.
ROSIE: Weatherize, window AC units, portable AC units. What about ye olde time fan?
THOM: Fans are where it's at. I generally prefer fans to air conditioning myself. So we have fans propped up all over our houses. Now we have a heat pump, so we do use the AC a lot more now. But the fans also help to keep the cold air then circulating around the house, which makes it even better. As I said earlier, if you do have a larger air conditioner in your home, you can use some extra fans to pull the air away from your living room or wherever and redirect it so that it moves into other parts of the house.
CAIRA: Yesterday, my partner and I were debating if it's better on a boiling hot summer day to have a breeze that's blowing hot air or no breeze at all. So to that end, if you have no AC unit but you do have fans, are you hurting yourself or are you helping by circulating the hot air, even though there's no cool air coming in?
THOM: You're still helping yourself. On a very basic biological level, our bodies sweat, and the purpose of sweat is to cool us down when the wind comes by. So even if it's a hot day and you only have hot air in the house, you're sweating. And a fan is still going to blow the moisture, the sweat off your skin, and that's going to make your body cool down. That is literally our most basic biological cooling practice.
ROSIE: Well, and then you have ceiling fans.
THOM: Ceiling fans. If you have a ceiling fan, just leave it on all summer. One of the neat tricks with ceiling fans is that they work just as well in the winter and the summer, but you have to make sure you change the direction of the fan. So warm air is lighter than cold air, and it rises up into the room. So during the winter, you want to run your ceiling fan clockwise, which will then help to push the warm air down to the room so that you're not losing all the heat you've been generating and paying for.
Then during the summertime, you want to run the opposite direction. You want your fan to run counterclockwise, so that way it pulls the warm air up and out of the room and keeps pushing the cooled air back down so you're not overusing your air conditioner. Otherwise, your ceiling fan would basically be dumping your AC air over into the next room or out the window or whatever, and you don't want that.
ROSIE: The more you know.
CHRISTINE: There we go, there we go.
ROSIE: I've lived all these years, I never knew. Thom, thank you so much for joining us. Our thanks to Liam McCabe. Thanks, Thom.
CHRISTINE: Thanks, Thom.
CAIRA: Thank you.
THOM: Thank you.
CHRISTINE: After we recorded our interview with Thom, our favorite window AC, the Midea U, was recalled. And most if not all Midea U buyers are eligible for either a prorated refund or a repair kit from Midea. They might also send out a technician in some cases to help you fix the unit.
ROSIE: And this is one of those inverter compressor ACs we discussed earlier in the show. So for listeners who have this AC, and it's a very popular one, we wanted to give you a quick cheat sheet on what to do. So Christine, give us the who, what, where, when, why.
CHRISTINE: This Midea U air conditioner, which is recommended by Wirecutter and a bunch of other sites, it was recently recalled over complaints about mold growing on the fan inside the unit. Listeners should keep in mind that mold can actually grow inside any air conditioner. It's not just the Midea Us, but this is an issue for this particular one. So it's important if you do have a Midea U you should be participating in this recall.
ROSIE: Okay, so what should folks do to check if they're affected?
CHRISTINE: To check your media for mold, you should look inside the grill. We're going to put a diagram in the show notes and see if there's any mold growing there.
ROSIE: So, probably use a flashlight or something like that to check.
CHRISTINE: Yes, absolutely. Use a flashlight, or a headlamp.
ROSIE: And then if you find mold, or if you suspect there's mold there, what can you do?
CHRISTINE: So, like I said, all Midea buyers are eligible for some kind of refund, but the amount varies depending on how long you've used the unit. You can get on Midea's site and check your model number to see if you're part of this recall. To get the refund, you'll need to fill out a form online, and then the company will either have you return the unit with a prepaid shipping label, which seems not many people are going to do that. These are huge units. They're very heavy. Or they will ask you to cut the cord and take a picture of it and send it to them. But if you'd rather keep the unit that you already have because it's huge and maybe you don't see a lot of mold in there, the company will mail you a DIY repair kit to help the AC unit drain better, which is essentially the issue. If your AC doesn't have a drain plug already, the company says it will send a technician out to drill one.
ROSIE: And then what can folks do to reduce the chance of mold growing in their AC unit to begin with?
CHRISTINE: Anyone with a window AC unit should really be running the fan, because that'll help everything dry out inside. And that's particularly true for these models, like the Midea U, which are these inverter compressor units. So run the fan. Keep things blowing, kind of like when you run the pan in your bathroom after a shower.
ROSIE: There you go. Thanks for that, Christine.
CHRISTINE: No problem.
ROSIE: Today, we had a double hitter, Thom and Liam.
CHRISTINE: We had the heating-cooling super duo.
CAIRA: I really didn't think I was going to find it so interesting to learn how AC units worked.
ROSIE: Who knew?
CHRISTINE: Yeah.
ROSIE: What are you guys actually taking away from this ep?
CHRISTINE: Well, I was totally shocked and surprised when Thom explained why some of these larger window air conditioners that don't dehumidify as effectively. It really hit home for me why one of my rooms is not as cool as comfortable feeling as I would like it to be. But I think that I might consider getting a dehumidifier also if I can't get that room to be more comfortable.
ROSIE: Yeah. The idea that if your AC isn't working as well as maybe you hope or want it to be, it could be a question of humidity.
CHRISTINE: Of humidity, and not just cooling.
ROSIE: Making you uncomfortable, yeah.
CHRISTINE: Right, exactly.
ROSIE: My take-away, honestly, is simple weatherizing.
CHRISTINE: Yeah. We will also link in the show notes, we have some very specific recommendations for different weatherizing tools.
CAIRA: I love that. My take-away is from my talk with Liam because... So I'm going to save up some coin, but then eventually in the future, I think I might actually go with a split AC unit because it's still an easier construction job than building ducts to get a whole heat pump system.
CHRISTINE: Yeah.
ROSIE: Look for those incentives.
CAIRA: Yeah.
ROSIE: Get a loan.
CAIRA: Yeah.
ROSIE: Low interest.
CAIRA: With 0% interest.
ROSIE: With 0% financing.
CHRISTINE: That's right.
ROSIE: Well, if you want to find out more about Wirecutter's coverage of ACs, splits, heat pumps, any of it, check out our website. As ever, you can find a link in the show notes. You can check out Thom and Liam's reporting. Stay cool out there. That's it for us this week.
CAIRA: Thanks for listening.
CHRISTINE: Bye. The Wirecutter Show is executive produced by Rosie Guerin, and produced by Abigail Keel. Engineering support from Maddy Masiello and Nick Pittman. Today's episode was mixed by Katherine Anderson. Original music by Dan Powell, Marion Lozano, Alicia Baetube and Diane Wong. Wirecutter's Deputy publisher is Cliff Levy. Ben Frumin is Wirecutter's editor in chief. I'm Christine Cyr Clisset.
CAIRA: I'm Caira Blackwell.
ROSIE: And I'm Rosie Guerin.
CHRISTINE: Thanks for listening.
BLOOPER
ROSIE: Where in Boston do you live, remind me?
LIAM:
I'm out in Natick, I think you said you have some cousins out here?
ROSIE:
Natick, yah! I sure did.