Tag Archives: Air conditioner

Being a Baked Potato

Feel like a baked potato?

Feel like a baked potato?

Our Airstreams are beautiful. They are also wrapped in aluminum just like a fine baked Yukon Gold potato would be. Why do chefs wrap potatoes in aluminum foil? I asked.

Aluminum conducts heat quite well. That means it moves heat from one place to another efficiently, such as from the outside of an Airstream to the inside. Be thankful Wally B didn’t use copper to skin his Airstreams as it’s an even better heat conductor than aluminum.

By wrapping a potato in foil, heat is transferred/conducted from the oven into the foil sphere where the potato is and the potato cooks. The foil keeps moisture in, heat in, and it heats more evenly. It also keeps the potato warmer longer after it is removed from the heat source. So, when inside an aluminum trailer, if you sometimes feel like a baked potato it’s for a good reason. You are.

Heated air rises and cooled air sinks. And to support that fact, the cat likes to lay on the floor when it’s hot rather than lay on the top of the lounge pad to gaze out the window. Makes sense. The air conditioner unit, being mounted high, generates refrigerated cool air which naturally sinks to the floor and displaces any warm air because cool air is heavy and dense. Warm air molecules rise (think of a hot air balloon) because they are expanding and lighter than the cooler air molecules around them. This high pressure (cool and dense) and low pressure (warm and light) exchange is something we need to manage inside the trailer to stay comfortable.

The Problem

As the warm air inside the trailer rises to the ceiling where does it go? If you use a pressure cooker ┬áto heat liquid on the stove the liquid’s temperature can increase beyond normal. Why? Because by keeping the pressure up (high pressure = cool), the temperature where boiling occurs goes up and the liquid does not readily boil. Maybe the same holds true for the inside of the hot trailer.

If you turn the A/C on and close all the windows you have kind of created a pressure cooker. Heat from the sun bakes down on the cool trailer and the cool air inside wants to leave. Because the trailer is sealed up tight, the temperature inside rises just like a pressure cooker. The increased temperature will get to a certain level and sort of stay there. From then on, you’re mixing the cool dense air made from the A/C with the naturally occurring heated air from the sun via the aluminum siding and the temperature just creeps up. Sadly, due to the superior heat conductivity of the Airstream, and its lack of an efficient insulation system, the temperature rises rather high and it becomes uncomfortable.

The Answer

If the hot air is something we don’t want, we should figure out a way to get it to go away. If you want to prevent hot air from entering, you create barriers such as insulation to keep the cold and hot separated. If you want heat to go, make some cold air and create a path for hot air to rise. It’s hot air and natural law says it must expand. If it has nowhere to expand to, it creates higher and higher pressure and raises the boiling point. That’s NOT what we want. In an Airstream, during a heat wave, we want cool – not hot. So, what do we do?

Let it go. Let the hot air escape to the outside. The tricky part comes when we want to keep the nice heavy cold air. If we picture the cool air laying along the floor and the hot air moving around up at the ceiling, we might get the idea to let the hot air out one of the vents and let the cold air fill up the Tin Can! Brilliant!

And that’s just what I’ve started to do. I’ve noticed my A/C is doing a better job at keeping the temperatures livable inside my baked potato since leaving small openings in the two Fantastic Fans. The fans have covers made of Reflectix as heat barriers, but there’s enough gap for hot air to escape out the openings I’ve left in the vents.

You mileage may vary, but it is working for me. It’s the little things that count. Happy touring!