Usually, one would go for a portable air conditioner for reasons like mobility or no window accessibility. Some may use it to due to strict apartment and community rules regarding window AC. Despite greater flexibility through an outlet. What if you don’t have a window? What if you want heat in adjacent room? Is it possible to vent it into another room? Well, this article covers that in detail.
It is possible to vent a portable AC into another room but not recommended. Rejection of hot air in an adjacent room would reduce cooling effectiveness due to high thermal imbalance and heat conduction through walls and gaps. Automatic expulsion of moisture in most portable ACs will result in high humidity in outlet room potentially causing mold and mildew.
There are various configurations of rooms one may have in his home. Sometimes it may be a good idea to take advantage of the heat from the vent. However, it is better to know what is at stake and if it is really worth it or not.
Why Portable AC Needs to Be Vented?
Portable air conditioners like most air conditioners available in the market operate on vapor compression cycle. They use the process of compression, condensation, expansion and evaporation to reject heat from the refrigerant to outdoors.
During the operation heat is extracted from the space to be cooled and delivered to external environment. As a result temperature of the room is reduced.
What Happens If You Don’t Vent Your Portable AC?
Think about what will happen if you do not vent your portable air conditioner. If vent of your portable AC is in the same room heat that was supposed to be rejected outside is in fact rejected to the room.
This causes the heat to cycle in the same room. Your portable AC is doing nothing at the expense of energy it is consuming.
Electricity is wasted in taking the heat by refrigeration cycle and giving it in the same room. In fact this would cause the room to further heat up as heat from the operation of portable AC is also added is the room.
The only thing a portable AC does when venting in the same room is dehumidification. But this is true only if you didn’t have a portable AC with self-evaporative technology.
However, most of the portable AC in the market are either partially or fully evaporative. So, in most portable ACs humidity will be rejected to the same room too hence no dehumidification either.
Can You Vent a Portable AC into Another Room?
It is actually practical to vent a portable AC into a different room in your house. The possibility is due to the fact that you are not actually venting in the same room. Most basic requirement for cooling process of AC is that heat is not rejected in the same space that you are targeting to cool.
Well if it’s OK and doable then what seems to be a problem?
Inefficiency and Lower Cooling Effectiveness of Portable AC
The major limitation due to which this is not recommended is the inefficiency of the process. When you vent your portable AC in another room of your house. It is still in the house.
How Heat Leaks During Normal AC Operation?
When you cool a room by venting outdoors, your room is at a different temperature compared to the rest of the house. Hence heat tends to rush in through other sectors of your home due to thermally instability caused by cooling a single room.
Even if you have a close room (that you do during the air conditioning it) heat is conducted through the walls. There are minute air gaps present in the room even if it is pretty insulated, i.e. surroundings of window, under the door etc.
What Changes When Venting into a Room?
Now compare the above situation with when your portable AC rejects heat in an adjoining or adjacent room or any other room of your house. The temperature gradient in the house would be even bigger and thermal instability will be higher.
The heat transfer rate is directly proportional to temperature difference between zones.
Thus, this will cause more heat tending to escape from hotter region to your room causing very low cooling effectiveness. In other words, less cooling, more power consumption and more time to perform equivalent cooling.
Lower Energy Efficiency Ratio of Portable AC
EER (Energy efficiency ratio) is the ratio of cooling capacity of portable air conditioner to its power input. In other words it is the measure of air conditioner’s efficiency.
EER has a relation with condenser temperature. In fact a study conducted shows that in a typical R410a AC 20°F increase in outdoor ambient temperature resulted in a 25% rise in compressor power consumption, a more than 13% decrease in total capacity and finally a 28% decline in EER.
Results can be interpolated for any air conditioner as the operation is based on basic refrigeration cycle. This means that hotter the air in the location where you vent portable AC lower is the efficiency of your portable AC.
Effect on Performance of Single Hose vs Dual Hose Portable AC
This reduction in EER is true for both types of portable AC’s; Single Hose and Dual Hose.
Single hose portable ACs have a phenomenon called negative pressure. They intake air from the internal environment i.e., from within the room. This causes suction of comparatively hotter air than usual. Thereby causing less efficient operation.
In dual hose portable AC performance would be even lower as air in the hottest room in the home is used to cool the condenser. Normally they have higher efficiency compared to single hose portable AC.
High Humidity in a Room Could Cause Mold and Mildew
With cooling operation an air conditioner also removes humidity from the living space. Humidity is extracted from the atmosphere and collected in a condensate pan. So even if you are venting in another room, despite the inefficiencies, humidity is still reduced from the cooling space.
However most portable ACs in market have self-evaporating technology. This means that they automatically expel water extracted from the cooling space via vent hose. This would cause high humidity in the room where you are venting hot air.
High heat, humidity and food sources (organic material) create an ideal environment for mold and mildew to sustain and grow. Warm and humid conditions in the room where hot humid air is vented may be a good location for that. We definitely don’t want that to happen.
How to Vent Your Portable AC Outdoors Without A Window?
If you do not have a window in your room go for the next best venting option. Window in not a necessity for using portable AC. The real goal to just reject hot air outside.
There are various ways you can vent without a window. I would go with the one that is easiest and requires least modification in the room.
Venting Through a Sliding Door
If you have a sliding door in your room it could work for the vent of your portable AC. There are few problems that may not let you able choose this option of venting. Primarily that you sliding door is not opening to entrance, exit, balcony etc. to release hot air directly to external environment. Rather the door is opening in the middle of home. In this case this option might not be a good idea.
Second limitation could be length of vent hose of your portable AC. Normally portable ACs have vent hose from 5-7 feet long. It is recommended to keep vent hose’s length less than 12 feet. It is desirable to keep it the same that is selected by manufacturer.
So if in order to be able to reach your sliding door you have to alter the length of your portable AC, I advise you not to do that.
Venting Through Ceiling
If you have drop ceiling in your room that is usually common in comparatively old constructions then you may use that to your advantage. You can use a single tile to attach your vent hose with it. However you might want to consider a hose that is designed for the purpose (ceiling venting kit). The reason is that normal exhaust hoses are heavy and not suitable for this purpose thereby.
Venting Through Wall
If everything else mentioned will not work for you then vent through the wall. It is not that easy as other options. It is better that you hire a professional to do it. Before you use this method decide for how much time you use portable AC in a day. The hole in the wall will be permanent. So if you use portable AC for only a small interval of day try to make pervious options work for you.