We’ve talked about how air conditioners work, when to consider upgrades, how they came about… how we got cool before air conditioners, and more. Today, we’re going to tackle a downside to air conditioners. We’re not talking about electricity bills or maintenance costs or shattering your back when your boss demands a personal window unit for his office. We’re talking about heat management with portable air conditioners.
Keeping the Heat Out
If you’re a lucky person, like most of the world, you’ve probably only dealt with three types of air conditioners: Central Air Systems, Window Units, and Chiller Units. These systems are all pretty efficient and straight forward. Your central air has a scorching hot coil outside, and a freezing cold one inside. Your window unit puts a roasting hot coil outside your window and a freezing one right in front of a fan. Your chiller system probably sits on the roof somewhere and melts the air, but then sends icy water inside to keep you cool.
In all of these cases, we put the cool part in the house and the hot part where no one’s going to be bothered by it. There are however, cases where the fates bluntly say “screw you.” How do you air condition a room that won’t accomodate a window unit, in a house without a central cooling system? That is, any house built more than two decades ago, using weird windows or windows that don’t even open.
This is where portable AC comes in. Both coils are in the room. The evaporator and condenser are in the room. On the surface, this is a problem. You can’t make a room colder by moving the hot air from the room, back into the room. You can’t vent a kitchen if the hood over the stuff is just routed back into the room. No matter what, we’re going to have a challenging time making this work.
Portable air conditioners have a vent hose. It’s somewhat like your standard dryer. All the heat is pushed into the house and shoved outside where it does no harm. It’s a horrendously inefficient process. As the air is pushed out the vent, it heats the vent hose up. As the vent hose heats up, it heats the room up. You can see where this becomes a problem.
No matter how much the air conditioner works, it’ll always be battling itself to keep the room cool. To offset for this, you need more BTU, more cooling capacity to fight itself, to put more hot air into the room, to cool the room. It becomes a circular battle. It becomes a losing battle until you’ve bought a massive enough system to get comfortable.
The Better Alternatives
Portable air conditioners are really a tool of last resort. These things are only worthwhile if you’re in a space where a traditional unit wouldn’t work. In these cases, if your budget allows for it, consider having a contractor replace your window or install a permanent wall unit. It may be even worthwhile to consider the cost of just converting an entire facility to central air if more than one room are going to be difficult to cool.
These ‘special solution’ rooms are hopefully few and far between, but it depends on the age of your building and how stubborn the architect was about removing windows that open or cutting back on a good AC system. Unfortunately, I’ve been around a few places where a trendy window had to be used, and every room would need portable AC or a full system install.
The Wrap Up
We came down pretty hard on Portable AC, so let us know if we were too harsh, if you’d do something different, or if we got something wrong. As always let us know what you’re interested in, in the comments below.