Allergy & Air on March 9, 2015 38 Comments In the last few years, portable air conditioning units have been growing in popularity. Whether it’s how much money they save you or just that people are tired of having bulky A/C’s awkwardly sticking out of their window, they are becoming the new must-have item for homes across the world. Instead of taking up precious window space, the portable unit has hoses to exhaust warmed air out through the window. The tubes are held into place with adjustable frames. Everything you need to install the unit comes in the box, but you’ll need access to a window in order for the unit to work correctly. When it comes to properly venting your air conditioning units, here are two main types that you should be aware of. Some units only have one hose, while others have two. Let’s take a closer look at the differences between dual hose and single hose air conditioners. What Do the Hoses Do? For a complete understanding of which type of portable A/C unit is best for your home, you should understand the purpose of the hoses. No matter which option you choose, every portable unit must draw air in from one vent and then exhaust it from another part of the machine. The exhaust is sent outside of the home through one hose and air may be drawn into the unit through another. It can also help you to know that any air conditioning system actually makes more heated air than it does cool air. The efficient removal of heated air is absolutely necessary if the room is to be cooled. Single Hose Air Conditioning Units The main difference between the two different options is, of course, that one unit has a single hose and the other has two. The single hose air conditioner pulls warm air from the room, sends it past coils cooled by refrigerant, and then sends heated air and moisture through the hose and out of the house. This does create a negative air pressure situation as air is pushed out of the room. The result is that any cracks around doors and windows will allow hot outside air to leak into the room, and will actually pull that hot air into the home. If the area being cooled is very big, the machine will have to work harder and harder to cool the room. On the other hand, if the area isn’t big, then the one hose system can provide sufficiently cooled air without costing too much. There are a couple of important things to keep in mind here: The single hose air conditioner is meant to be temporary and portable. This means that it is easy to move it to the specific areas of your home that need cooling. For the single hose portable air conditioner to be effective, you need to very carefully determine the BTUs of the machine you’ll be using. If you intend to use the unit in a room with computers or even a mini-fridge, you’ll want to choose a more powerful machine. Dual Hose Air Conditioning Units The other type of portable air conditioning unit is the dual hose unit. This model has a couple of intakes and one outtake hose. Through the intake, air is drawn into the unit where it is cooled and then sent back into the area. The machine heats up through the process and an intake hose pulls air from outside the home to cool the air conditioner down. A second hose sends all of the warmed air outside of the home. With this efficient exchange of air, the dual hose system doesn’t have to work nearly as hard as the single hose option. For larger spaces, the dual hose A/C unit is a better choice. The dual hose machine eliminates the negative air pressure problem, but also costs a bit more. This air conditioner operates more quickly than the other and also requires more electricity. Compare BTU and EER ratings, as well as manufacturing quality to determine which of the models are most appropriate for your setting. The Importance of Good Research When temperatures begin to warm uncomfortably, you may feel tempted to purchase an air conditioning unit as quickly as possible just to get comfortable. You will enjoy better results, however, as you take time to research the different options and compare the benefits and drawbacks of those options. In fact, the best time to make this decision is probably before the red on the thermostat starts to rise. With time to do some research and take measurements, you’ll be able to get the air conditioning system you want in place before there’s any chance of being uncomfortable.
Chin says August 19, 2016 at 5:39 am Seriously confusion article: Really two intakes and one outtake for dual hose portable? These is Condensor is cooled by outside air drawn from hose and exhausted via another hose. Air inside the room is circulated over the evaporation coils which cools the inside air. Dual hose no different an window AC in function other than the fact in does not sit in the window exposing Condenser and condenser fan outside the window, rather air is drawn via hoses to cool condenser Reply
Larry says August 30, 2016 at 9:50 pm Read carefully. It’s actually pretty clear assuming careful reading. Reply
Harvey says September 22, 2016 at 6:03 pm I have to agree with Chin because the first paragraph explaining dual hose units really is confusing at first. (It REALLY DOES say two intake and one outtake hoses, for a total of 3, when explaining a dual-hose unit.) I had to read it a couple of times before I finally understood what the author was saying. That not withstanding, the article was informative. Reply
Tony Power says December 4, 2016 at 4:44 am To clear this misinformation up (i) The single duct unit draws in more outside air than it delivers cools air to the conditioned space. This means it will never cool other than if you are directly in front of the unit. Thats what the negative pressure comment is about (ii) A double duct unit draws condenser air in from outside and discharges hot air (thats where the work is done) to outside the building. This is proper engineering practice. Less energy cost overall and hugely more efficient (iii) Never buy a single duct unit Hope that makes sense and saves some unhappiness Reply
Erich Riesenberg says December 18, 2016 at 8:03 am This is how Friedrich describes their dual hose model. Friedrich claims “only indoor air is conditioned and returned into the room.” So what happens to air drawn in from the outside? If that air is not conditioned, why draw it in at all? Reply
Andy K says January 30, 2017 at 6:00 pm Hi Erich The outdoor air is heated and returned to the outdoors. It is not possible to simply make hot things cold – the heat has to be moved somewhere. So in a single duct, the heat is pushed outside, but doing so draws in more hot air from elsewhere. In a double duct, hot air is pulled in from outside, even more heat is added to that hot air by cooling, and then it is pushed back outside through the other duct Reply
leonard barker says October 19, 2017 at 11:55 am All this bull is to hid the fact that a single hose unit uses the conditioned air in your room to exhaust the hot air created from the condensor. Not very efficient because you are blowing your cool room air to outside. Reply
Jay says April 20, 2017 at 10:28 pm Only dual hose units make sense. Room size has little to do with single or dual hose. Single hose systems send (probably cooled) room air out of the duct to the outside. Dual hose units do not. Think on these things. Huge difference in efficiency. Reply
jordan says May 2, 2017 at 6:53 pm This finally makes sense after reading the comments. The article says there’s multiple intakes, but only one outtake, which is quite misleading. There’s a set of both exterior intake and outtake, as well as interior intake and outtake. I never realized they were separate systems. I always wondered why would I want to pull hot air in from outside to cool, when I can pull cold air from inside and cool it further. This makes sense why that won’t work when you take the negative pressure issue into play. I also wondered why the two vents were right next to each other. Wouldn’t you just pull the hot air you spat out, right back in? Glad to know that’s not how it works. Reply
Brenda says May 20, 2017 at 6:33 pm Help! Should I get a single or double vent? My outside air at night can be 100. Seems like drawing in air that hot would be hard for the unit to cool it down, versus using the room air which is already cool. Reply
Tom Wilson says June 13, 2017 at 6:07 pm You should *always* buy a dual hose AC. Dual hose AC’s are more efficient, using less energy for the same amount of actual cooling. I’ve had both and will never use a single-hose again. Reply
Tom says February 23, 2018 at 10:10 am Will a dual hose (Or single hose), work when it is very cold outside? The unit will of course be inside but the hoses going out as usual. Need the cooling year round in this application. Would be anywhere from 0 Celsius to -40 celsius outside in the winter. Reply
Wolfgang says June 19, 2017 at 2:41 pm For every liter / gallon of air you push out of your room there is one liter / gallon of air coming into your room. It comes either through a exterior intake and does not mix with your already cooled inside air as the dual hose unit does. Or it comes through your door and the hot air coming through your door is mixing up with your already cooled air, as the single hose unit does. Reply
Dunn says July 25, 2018 at 5:52 pm Exactly my thought also. Outside air could potentially be warmer than the inside air. Take in example. An automotive system. If you close the outside air source (recirc)you will be cooling the conditioned air rather than the outside warmer more humid air. Reply
Leona Ferguson says May 28, 2017 at 7:00 pm Does a conditioner with a single hose require a tube to be hooked up to the drain, or is that only in the humidifier setting? Reply
Wolfgang says June 19, 2017 at 2:46 pm Cooling always comes with condensation. But some devices claim to be able to evaporate the condensed water (coming form cooling down the interior air) into the hot outgoing air. So they don’t need a drain. Reply
Diane says June 15, 2017 at 9:14 am Not to complicate things but I just bought a dual hose and my question is this. While the machine is running, is one hose suppose to be really hot and the other cool? Reply
Ray says July 7, 2017 at 1:11 am Their description is not correct between a single hose and dual hose unit. An A/C is compose of two coil components. The evaporator and the condenser. The evaporator expels cool air and the condenser expels hot air. Air most flow past both coils for a unit to work. The question is where is the source of the air to pass by the coils. Single hose units. Room air is taken in and passed by the evaporator coil to expel cold air in the room. Now air is also needed to pass by the condenser coil. It too is also sourced from the room and push past the condenser coil and expelled outside via the single hose. So not only are you creating a negative pressure difference but you are taking cooled room air and pushing it outside. Dual hose unit works the same for the evaporator coil but uses one hose to pull in outside air with is passed by the condenser coil expelled back outside. Benefit is you are not creating a negative pressure and you are not using cooled room air to pass by the condenser coil. This is just like how a central A/C works. The outside unit has the condenser coil and uses the fan in the top to pull air thru the coil to expel the hot air. Reply
Derrick says July 10, 2017 at 2:05 pm What I read is dual hoses is more efficient but cost you more on your electric bill. That’s confusing to me as well. If I buy a more gas efficient car. I get better gas mileage saving money. So if you buy a more efficient dual hose AC unit; how do I pay more on my electric bill? Reply
James says July 19, 2017 at 12:25 pm Dual is more efficient but more expensive to buy, single hose is cheaper to buy but doesn’t really work. Reply
richard says August 5, 2017 at 11:31 pm what doest make sence to me is your are explaining it like the air is being cooled down but in fact the air is not cooled down the way ac works is it sucks heat out of the room leaving the cool air in am i mistaking in this idea Reply
Kellie says August 22, 2017 at 1:52 pm Why does the dual hose A/C more use electricity if it is more efficient? That doesn’t make sense. The article says the dual hose unit operates more quickly and also uses more electricity. So, how is it being more efficient if it is using more electricity? Logically, both units perform the same ultimate function, regardless of which one is quicker. Therefore, it follows that the unit using MORE electricity is actually LESS efficient, right? Reply
himukala says December 12, 2017 at 7:23 pm How does a split AC system works? As I understand there is no exchange between inside and outside air. Reply
Hedley Finger says January 24, 2018 at 1:30 am The internal unit draws in room air through a finned coil which transfers heat from the air to the refrigerant flowing through the coil’s pipe. Heated refrigerant is pumped outside where it flows through another finned coil in the outside unit. Outside air is blown through the fins of the outside coil so that heat is transferred from the refrigerant to the outside air. So no air is exchanged between outside and inside, but refrigerant flows around a closed circuit which has one loop inside and another loop outside. So only the heat is transferred from inside to outside. Think of a refrigerator where the compressor transfers heat from inside the cabinet to the outside the cabinet. Reply
Maria MCkenzie says May 11, 2018 at 1:05 am Do either type of A.C. remove cigarette smoke/smell and bring in fresh air like an air exchanger? Reply
Joe says May 20, 2018 at 5:16 pm Probably a crazy question.. can I set up a dual system into one duct discharge pipe going to the exterior of the house… Reply
Mike says July 1, 2018 at 4:45 pm NO. If you did that, the super hot air would simply be sucked back into the intake. It would be like taking a warm bath to cool off. Reply
Dan says June 21, 2018 at 9:39 am Can I run it without the intake hose on? So the only the hot air is vented out and the ac is pulling air from inside the house. Reply
Pam says June 22, 2018 at 7:52 am Can anyone recommend a particular dual hose air conditioning unit? have you had good luck with a particular brand? Reply
Warren says July 4, 2018 at 1:55 pm Pam, I have had an 11,000 BTU Whynter dual hose unit now for 2 years in my finished insulated 11’X21′ room above my garage (with a pull down stairway). We have used this room for guests to sleep in, I do some craft painting up there and keep my amp and guitar up there. If it’s 98 degrees outside it’s much hotter in the upstairs room but after 3 hours it’s cooled down to 75. If left on around the clock the unit shuts down auto when reached it’s setting (75) and back on when necessary. I have never run it for an entire month but certainly could. Usually just run it for 4 or 5 days successive days and have not noticed a noticeable increase in electricity usage. My unit is fantastic and performs exactly as advertised. I highly recommend this. Reply
Mike says July 1, 2018 at 4:43 pm most dual air machines actually do pull air from 2 sources…they do pull air in from outside, but also from inside through venting at the bottom of the unit near the coil. the fresh air intake hose does not pull in anywhere near the same amount of air that is blown out the hot air hose because it is not the only source of “fresh air”. It does however control the air needed to control the pressure problem. Reply
jrg973 says July 2, 2018 at 12:20 pm Can someone explain what happens to the condensate water from cooling outside humid air. Non of this is discussed in the reply’s. Reply
Warren says July 4, 2018 at 1:57 pm Pam, I paid $299 two years ago and now they’ve gone up to around $340. Good Luck! Warren Reply
Chris Jones says July 4, 2018 at 9:21 pm There are some “single” hoses that are in fact a dual hose: inlet in one of the hose’s chambers and outlet through the other chamber; much like the dual pipe chimney for condensing furnaces and boilers. Reply
Mark says September 23, 2018 at 4:55 am Can you please provide models? That is exactly what I am looking for. can not find any examples. Reply
Tyler says July 16, 2018 at 4:42 pm It’s important to use a dual hose air conditioner if you can afford it. Basically a dual hose system is the most efficient as it sends hot air outside and doesn’t suck down your interior air. Basically it has one “intake” and one “exhaust” kind of like how a car works. You can rig a single hose AC and turn it into a dual hose AC by just getting some hvac tape, an extra dryer hose from the hardware store to attach to the “intake area” on the AC and then connect it to an open window point. You can use cardboard or whatever you can find to seal the gaps around the air hose. This rig me up saves you hundreds off the cost of the AC. Reply
Mark says September 23, 2018 at 5:00 am I noticed this comment below. “There are some “single” hoses that are in fact a dual hose: inlet in one of the hose’s chambers and outlet through the other chamber; much like the dual pipe chimney for condensing furnaces and boilers”. Can anyone provide an example? I have casements, can not use an adapter, but do have and a single large dryer type vent. something like this would be a perfect solution. Reply
