You probably heard about an amazing portable air conditioner that was ventless with no exhaust hose to put out a window, but does it really exist? The truth is surprising but perhaps not entirely unexpected!
First of all, I need to dispel that particular myth about a portable room AC that doesn't need to be vented to the outside. It does NOT exist!
Why a Portable AC Needs an Exhaust Vent Hose
All air conditioning devices that make use of the refrigeration process to chill the air (and that's ALL of them) produce a lot of hot air and excess moisture. That's what needs to be gotten out of the room being cooled by the device, or the room will actually heat up!
Fixed AC units are physically connected to outside condenser units. They extract the hot, moist air from the room and expel it into the outside atmosphere where the person sitting in their nice cool room indoors doesn't need to be concerned about it.
But portable units do not have an external unit to connect to. Otherwise they wouldn't be very "portable," would they?
So to exhaust the hot air out of the room, they make use of a flexible plastic vent hose. It can either be hung out a window or connected to a window fixing kit that looks a lot tidier but performs much the same task.
If you leave the hose in the room (or don't bother even fitting it to the back of the AC unit), the unit will actually pump out hot air direct into the room (as well as cold). That hot air actually heats the room up faster than the AC cools it!
I know this because I've tried it, just to see!
What is a Ventless or Hoseless Portable AC?
Sure, you've probably seen them advertised or promoted in a big hardware store as "ventless air conditioners."
But those cooling appliances that look very much like ACs, but without the hoses and/or window kits, are NOT air conditioners at all.
They're called evaporative air coolers (or swamp coolers). They cool the air in a very different way to refrigerant-based AC appliances.
Let's look at these amazing coolers and focus on the pros and cons of getting one (or more) for your home.
Here are some examples of these great coolers that are on sale right now online at Amazon:
These coolers use a very simple method to cool the air. That is to draw room temperature air through a damp, sponge-like medium, evaporating the moisture which chills it. Then to force the now cold air out the front of the unit to cool the whole room.
Some models have a simple pump to keep the medium wet, while others rely on gravity, which works surprisingly well.
Most models allow you to add ice to the water reservoir tank in the unit to make the expelled air even colder.
Let's look at the advantages and disadvantages of this very special type of cooling device:
First of all, the good side, or pros of owning and running a swamp cooler:
All the work is done by a simple fan, which uses very little electricity (typically 100-200 watts) compared to the energy sucking compressor and refrigeration process of a comparably sized portable AC (typically around 2,000 watts). That makes swamp coolers very economical to run indeed compared to AC, which is good news if you're on a tight budget.
It's also good news if you are environmentally aware and considerate because when you use less electricity, it means less needs to be generated. That means less fuel needs to be used, with lower pollution levels and less damage to the ecology.
Because there is no refrigeration and heat exchange process at work inside these appliances, there is no hot air produced.
That means there is no need for a vent hose (or in some cases dual hoses) to hang out a window, which is doubtless the main point that drew you to read this article in the first place!
There were some great plus points for these awesome cooling appliances. Now let's look at the minus points:
The major flaw in this method of producing a cooling breeze is that is doesn't work so well in humid conditions. The reason is pretty simple:
For cooling by evaporation to be effective, the air needs to be "dry" so that it can accept the cold moisture (water vapor) that is fanned out of the cooler. As the level of moisture in the air rises (high humidity) it gets to a point where it becomes saturated with moisture and can't hold any more.
At that point, the cooling effect of air being blown through the moist medium is reduced because it can no longer be effectively evaporated into saturated air. One solution is to open a window to allow fresh, drier air to circulate in the room, but if the outside air is also very humid, the problem persists.
For this reason, evaporative coolers are not recommended for people who live in areas that have very high humidity through the hot summer months. In that case, traditional AC needs to be used (with doors and windows closed) to effectively cool a room or a building.
Refilling the Water Tank
Another disadvantage, although this is more of an inconvenience than anything else, is that the water reservoir tank needs to be refilled periodically to stop the medium drying out and ceasing to cool the air. Many models come with large capacity tanks (several gallons) so they only need refilling once a day or so.
Very large units that are also suitable for outdoor use come with a hose attachment so you can hook up the water reservoir to a standard water hose and simply turn on the faucet and have a constant supply of water!
Buy an Evaporative Cooler Online
There is more good news for those folks living in areas of low humidity that want to save money on their cooling costs. You can buy some of the best portable evaporative cooling units online at great prices and in certain circumstances, low cost or even free delivery!
It's not such great news for the majority of people living in a humid climate, where the only realistic alternative is a regular AC. But when push comes to shove and you need some respite from the oppressive humid heat, there is a newer, more efficient and economical type of portable self evaporating air conditioner available (you can read about them by clicking that link).
However, since the mission of this article is to promote energy saving cooling systems and solutions to people that can use them, we can recommend some of the best, low-running-cost swamp cooler models available today (see my Amazon picks above).
If you want to know more about how evaporative cooling works, see this Consumer Energy Center article.
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