Wall Mounted Air Conditioners

Wall Mounted Air Conditioners

Mike Cappuccio, founder of N.E.T.R., Inc., discusses wall mounted air conditioners and the difference between old-style through-the-wall AC units and modern ductless air conditioners and heat pumps.

John Maher: Hi, I’m John Maher. I’m here today with Mike Cappuccio, founder of N.E.T.R., Inc., a heating and cooling company in Massachusetts with a focus on Mitsubishi ductless heating and cooling products. Today, we are talking about wall mounted air conditioners. Welcome Mike.

Mike Cappuccio: Good morning John. How are you? 

What Are Wall Mounted Air Conditioners?

John: Good, thanks. So Mike, when people talk about a wall mounted air conditioner, what are they generally referring to?

Mike: Well, I think there’s some misconception on that a lot of the time. I want to roll the clock back maybe 20 years ago where people would take an air conditioner and they would cut a hole in an actual wall of a home and maybe frame it out and maybe it was 3 feet by 18 inches, let’s say, and they would take an air conditioner and just kind of stick it through the wall. And it was actually a “wall mounted air conditioner” at that point.

John: So that would be basically like a window air conditioner, but they’d be putting it into a hole in the wall.

Mike: Yeah, they called them wall mounted air conditioners and there was actually a unit — you actually had a window unit and a wall mounted air conditioner unit back in the old days, because you were putting it through a wall that was roughly about four inches thick and a window is only about an inch and a half thick. So the frame actually had to be a little bit longer on those wall mounted air conditioners that were going to go into a wall. So the air could be extracted to the outside. But I think a lot of people get confused now in today’s market when they say a “wall mounted air conditioner”, because they see these new Mitsubishi electric wall mounted units when they go into a restaurant or into an establishment where they have a unit mounted on the wall, and they see this wall mounted air conditioner, and they’re like, “Oh, okay, that’s a new wall mounted air conditioner from Mitsubishi Electric.”

And in reality, yes, it does mount on the wall, but there are some other things that go with that too. I mean, there’s a couple of pieces that go outside. There’s refrigerant piping that goes with that. And then there’s what we call a condenser that would be placed outside the home. So the unit is wall mounted. You definitely do mount it on the wall and you drill a hole in the wall and then you run refrigerant pipes outside to a condenser that would be placed outside. That’s where the actual heat is being removed from the home through the condenser outside.

John: Right. And the hole that you’re drilling in the wall is not, like you said, 2 feet by 18 inches. It’s just like a small pipe, a pipe that’s going through the wall.

Mike: No, roughly, It’s about a 3 inch hole that gets made in the wall where the pipes…there’s two pipes, a drain for the condensate because any air conditioner removes humidity from the space too, and that’s the condensation that’s leaking outside. So there is a drain line. And then there’s electrical wiring from the indoor wall mounted air conditioner to the outdoor unit as well.

And then when that unit gets mounted on the wall, when that hole gets drilled, there’s actually a sleeve that goes in the wall because the sleeve…basically it’s almost like a piece of PVC that goes into the hole and then the pipes and everything go into that sleeve because what you don’t want is the warm air from inside the wall being able to enter the back part of the wall mounted air conditioner at that time, because that’s the sensors for all of the monitoring, I guess I would say, for the temperature set point. You don’t want to be offsetting that by warm air in the wall. So, you kind of block that off by a sleeve and you seal both from the outside and the inside through the sleeve.

How Is a Wall Mounted Air Conditioner Vented to the Outside?

John: So does a wall mounted AC unit need to be on an outside wall in order to vent? Or how is it vented?

Mike: No, absolutely not, John. They can be mounted on interior walls, exterior walls. A lot of them do get mounted on interior walls. And I can explain to you a little bit how we would take that wall mounted air conditioner, and actually put it on an interior wall. I want to give you an example of a home where you might have an unfinished basement or a garage below, and you can put a unit to the left or the right of a closet opening and run the pipes through the interior wall, down through the closet. And typically like to tuck the piping into the corner of a closet and cover it with a nice white line hide and then drill a hole through the floor and bring the refrigerant pipes, drains and electrical into the basement and then run them outside. That’s how you do an interior wall.

You can also put the piping inside of the wall. I want you to kind of think of an interior wall in a home. Most interior walls in a home are hollow. It’s a two by four wall that is hollow. And if you go down into the basement, you can always see electrical lines that run up into the hollow wall, where there’s an outlet. You kind of pinpoint where the hole is and you drill a three inch hole up into the wall from the basement and a hole in the wall and you drop a snake down and you fish the pipes right down through the interior wall of the home too. That can be done as well. We’ve done that a few times too. So, I mean, it really doesn’t matter. Then an exterior wall of a home like we spoke about earlier was mount the unit on the wall, drill the hole, go to the exterior of the house with the piping drain and electrical as well.

Are Wall Mounted Air Conditioners More Cost Effective Than Traditional Window AC Units?

John: Okay. So are wall mounted air conditioners more cost effective when compared to a window air conditioner or one of these old-style wall mounted air conditioners like we were talking about before?

Mike: Oh yeah. Let me explain to you a little bit why, John. On the ductless systems, we’re going to call them — or wall mounted air conditioners as we’ve been referring to them the last five minutes or so — they’re all inverter driven compressors. Basically they speed up and slow down on demand of what the room needs for temperature. Now, I want you to think back to an old wall mounted air conditioner, how they worked, you would hear the compressor kick on. And then all of a sudden it would run up and you’d see the lights dim on the dining room table or the kitchen. And sometimes the house, the wall would actually shake sometimes. And the compressor was an on/off system. Basically it turned on when it needed cooling and it shut off when it didn’t need cooling.

Whereas the new systems now, they basically speed up at a very low, low speed and they don’t pump, they spin; they’re a scroll compressor that turns, it doesn’t have a piston that goes up and down. So it’s a lot quieter and it speeds up as the room needs more cooling. The compressor speeds up to a faster speed. And as the room cools off, it slows down to a slower speed. So it really doesn’t turn on and off, on and off. And that’s how you pick up the efficiency, because when you see those lights dim, that’s a big spike in amperage. It’s just grabbing all that power and that starting current to start up that compressor, these new wall mounted air conditioners started at a very low speed. They start around 30 Hertz, whereas a regular unit starts at 60 Hertz of electricity.

And then we ramp from 30 to anywhere to 120, to 150 Hertz. And then we slow down, back down to 30 Hertz when we come down. So again, we don’t have that big light dimming and that big grabbing of amperage to get the compressor started. That’s how we pick up the efficiency.

John: Right. And the fact that, like you said, it doesn’t have to be on all the time or off all the time. It turns on, ramps up its speed to cool off the room quickly, or heat up the room in some cases, and then when the room reaches the right temperature, then it just scales it back, so that it’s just running at this very low speed. Right?

Mike: It’s a lot like…consider highway driving and city driving. You know, the old wall mounted air conditioner was city driving, on and off the gas, on and off the gas. Whereas highway driving, you speed up, you go out onto the highway and then you decelerate going at a nice fast speed. That’s when you pick up the miles per gallon, it’s very similar to what we’re doing with our wall mounted air conditioners now.

John: Right. You don’t have to keep your foot on the floor the whole time.

Mike: A wall mounted air conditioner, the old style ones, is just pedal-to-the-metal all the time; get to the red light, stop, green light, go, on, off, on, off, on, off.

John: Yeah. And we all know that you get better gas mileage on the highway than you do in a city.

Mike: Exactly. It’s the same thing with our air conditioners, exactly.

Are Ductless Wall Mounted Air Conditioners, Ductless Mini-Splits, and Heat Pumps the Same?

John: So, are a ductless wall mounted air conditioner, a ductless mini-split and a heat pump, all the same thing? I hear all those different terms.

Mike: Our ductless units, they consider them wall mounted air conditioners. They do come in just air conditioning only. You can buy a unit that just cools. But 90% of what’s being sold in today’s market is heating and cooling. And that’s what we call a heat pump. So that’s not a wall mounted air conditioner; that’s a wall mounted heat pump. And that unit heats and cools.

John: People still might think of that as being a wall mounted air conditioner, right? Because it can still cool off your room.

Mike: Oh, absolutely. Absolutely. But it can heat the room too.

John: Right. And then a ductless mini-split, same thing?

Mike: Same thing, same terminology, a lot of people get it confused with “wall mounted air conditioner”. I mean, it is an air conditioner that does mount on the wall, but it is really a ductless mini-split wall mounted air conditioner.

Are Wall Mounted Air Conditioners Easy to Install?

John: So, what’s the installation process for a wall mounted air conditioner. Are they easy to install?

Mike: Oh yeah. Most installations take anywhere from one to two days, depending on how many indoor wall mounted air conditioners you install. I mean, the average, what we usually see in a home is four of them, possibly one in each bedroom for two bedrooms and then probably one in the living room area or one in the kitchen or a dining room. A lot of times you go into someone’s home and you look, and the first question you want to ask is, “where do you live in your home? How do you live in your home? Is it just two of you? Is it just the husband and wife that live in the home? Basically, what areas do you live in the home?” Well, you’re going to find out, most of the time it’s bedroom, living room and kitchen and the spare bedroom might be an office at some point.

So those are the four areas of the home where we’d go in and put the four wall mounted air conditioners. And that takes about two days to install. Sometimes the wall mounted air conditioners go on interior walls. Sometimes they go on exterior walls depending on the actual installation. But like I said, there’s electrical that needs to be done. There’s an electrical feed that needs to run from an electrical panel to the outside condenser because there is a piece of equipment that does need to go outside and that would get placed on a pad and a stand. You want to put the unit up off of the ground for critters and squirrels and things like that can get inside of it. And the other reason why you want to keep it off the ground too, is in the winter time, when you are using this for heating, you don’t want to have to be going out there and removing snow or anything like that from it. They usually sit about 12 to 15 inches off the ground at that point.

What BTUs are Available for Wall-Mounted AC Units?

John: Okay. What BTUs are available in wall mounted AC units and how many square feet can they heat or cool?

Mike: Well, the average norm is about 20 BTUs per square foot is what you use for a rule of thumb when you’re sizing an air conditioner. But obviously you’d want to do what’s called a Manual J heat load calculation on the home to see how many BTUs it really requires, because it could require more BTUs due to big windows or things like that. But they range anywhere. The wall mounted air conditioners start at 6,000 BTUs and they go up to 36,000 BTUs. So they pretty much go about every half a ton. We refer to air conditioning in tons. So like a 12,000 BTU air conditioner is basically one ton of air conditioning. So a half a ton would be 6,000. So they usually go in sizes of 6,000, 12,000, 18,000, 24,000, 30 and then 36. Usually, it’s about every 6,000.

Can I Heat My Whole Home With a Wall Mounted Air Conditioner / Heat Pump?

John: Does a ductless wall mounted air conditioner, or I guess what you were referring to as a heat pump, does it just provide supplemental heat for my home? Or can I actually heat my whole home with it?

Mike: Well, there’s a couple different models in different units that actually do provide different amounts of heat. Now, I want you to roll the clock back again, 15 to 20 years ago. And there were heat pumps that didn’t heat when it was cold. You always heard about a heat pump that did not heat an area, and it had backup electric heat. Well, those days are pretty much gone, it’s a myth right now. But there are heat pumps that can give you full heating capacity at 47 degrees. And then there are heat pumps that will give you full heating capacity at -5 degrees. So, depending on the models that you buy, you can definitely heat your home with a heat pump in the winter time.

How Quiet Is a Wall Mounted Air Conditioner?

John: And what are the fan speeds like on a wall mounted AC, how quiet are they?

Mike: Well, they go down as low as 20 decibels. I mean, a human whisper, I think, is about 30 decibels. Pretty much you don’t even really hear the wall unit running when it’s running, compared to an old wall mounted air conditioner. That was so loud. You’d have to turn the TV up as loud as it would go, just so you could hear it. But I think the highest fan speed is about 45 decibels on that. So, you can hear the fan when it is on high, but at a very, very low clip, not even as loud as an actual window fan or a box fan or something like that.

John: And then, like you said, most of the time you’re not even running it at that full speed, or once it cools off the room to the right temperature, then it just ramps down and you don’t even hear it.

Mike: I know the unit I have in my office, I leave it on low fan and I don’t even hear it running when it’s running. My computer fan is louder than that, to be honest with you.

What Rooms Can I Put a Wall Mounted Air Conditioner In?

John: What are some of the rooms in my home where I can get heating and cooling with a wall mounted air conditioner?

Mike: Oh, any room, we can do kitchens, living rooms, dining rooms, family rooms, bonus rooms; home offices are very popular right now for wall mounted air conditioners; basement. A lot of people renovate their basement and they’re cold in the winter, they’re warm in the summer, good spaces like that. Additions are very, very popular with our equipment right now for them, putting an addition on the front of your home, back of your home.

And we look at a lot of homes when the builders are building those and they want to add a zone of air conditioning or a zone of heat off the existing system. Well, the one thing you have to remember is the existing system was sized for the existing home, and now you’re adding another thousand square feet and you expect that existing system to handle that extra thousand square feet; nine times out of 10, that doesn’t work. So our systems are very good for additions, renovations, things like that. We’ve done some tiny homes as well. I’ve seen a lot of people now where they’re working at home, have bought sheds, and they’ve put them in their backyard and made home offices out of some pretty nice sheds that they’ve put in their back of their homes; that we’ve done too. 

Do Wall Mounted Air Conditioners Look Good?

John:  What would you say to somebody who says, “Oh, well, I don’t really want to have this wall mounted air conditioner on the wall, above my windows or above my doors or whatever. I think it’ll kind of look ugly.” What would you say to those people?

Mike: Well, there’s a lot of different varieties, John, there’s now… There are units that actually go into the ceiling that can flush mount into the ceiling of a space. As long as you have space above it, that you could actually bring your piping and electrical. There’s the MLZ model that actually goes up that fits right between 16 inch on-center studs, where you actually cut a hole, like probably a 32 inch by 14 inch hole. And it goes up into the hole and it mounts flush-mount in the ceiling. That’s what we call our one-way ceiling recessed unit.

There’s also the floor mount unit that goes down low in a home. They look very similar to a radiator, but a lot nicer than an actual radiator. And those can be recessed into a wall too, as well, so it’s not like you have a big box hanging on your wall in your home. You have a wall mounted air conditioner that sits down low in the floor at that point. And it blows [air] up.

There’s also, instead of a wall mounted, you can do what’s called a ducted system from an attic down, or from a basement up, where we would put an air handler in the space and then cut vents into the ceiling, like a traditional central AC system. You can mix and match a ductless and ducted system. Now you can put duct work in one part of the home, and you can put wall mounted air conditioners in the other part of the home. 

Are Wall Mounted Air Conditioners Energy Efficient?

John: Okay. And in terms of energy efficiency, are wall mounted air conditioners energy efficient? Do they have like an energy star rating that we should look for?

Mike: They really have a few different ratings, John, they have a SEER rating and obviously the higher the SEER, the better, I mean the bottom line of a SEER rating is 13. That’s the minimum where it has to meet. Most of these units start out at about 20 SEER. So they’re more of a SEER rating. Then there’s an HSFP rating. There’s an EER rating. And those ratings, the higher the numbers the better. When you start looking at heating is where a lot of the HSFP and those numbers come into play. But they’re really not energy star rated. They’re more of a rating of a higher number, I guess is how I would say that.

John: All right. Well, that’s really great information, Mike. Thanks again for talking to me today about wall mounted air conditioners.

Mike: Thanks for having me, John.

John:     And for more information, you can visit the N.E.T.R website at netrinc.com or call 781-933-N.E.T.R, that’s 781-933-6387.