Tag Archives: Heat wave

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 ¬†to 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!

A Heat Wave and an Airstream

And the Dometic A/C has been on all day

And the Dometic A/C has been on all day

Like the record low temperatures experienced in January 2013, the high temps of June 2013 are something to learn from during my first year full-timing in an Airstream.

These past couple of days have been unusually warm for northern Nevada. Well, what would you expect for being in the throes of climate change? And isn’t it interesting to be aware of climate change, and to see it unfold? OK, anyway, it’s hot.

It was 100 degrees an hour ago and now it’s 99. The humidity, for your folks east and south of the Rockies, is 16%. Yesterday: 100; tomorrow: 101; Tuesday: 102. You get the idea. It’s hot!

Because I’m not so fortunate as to have a job where I can just work from home, I’m not on my way to the coast. I have an office to show up in tomorrow so here I am, but at least it will have a proper air conditioner and insulation. Not so in an Airstream.

It’s probably much like being a foil-wrapped baked potato, but with electricity and a bathroom. The aluminum walls are classic looking, but boy do they suck in whatever temperature you don’t want outside to the inside.

During the frigid winter, while the air inside was warm due to the heater being on, the walls had frost on them. Well, the summer is worse and it would likely be unbearable with the slightest wisp of humidity.

For the past two days, the Dometic 13.5k A/C has been running non-stop from 8:00AM to 8:00PM. The aluminum walls, when checked with my handy Raytek MT6 laser thermometer came out like this:

  • Next to the door, in shade – Exterior 101.5 — Interior 89.0 degrees
  • Interior ceiling, between the skylight and ceiling fan, no shade – 102.0 degrees
  • Floor – 77.0 degrees
  • A/C duct – 52.5 degrees
  • Next to bedroom window, in shade – Exterior 101.0 — Interior 92.5 degrees.

From these numbers, we see the interior walls are 9 to 12 degrees cooler than the outside temperature with the A/C running all day. Yes, all day. The temperature of the air inside ranges between 85 and 89 degrees when the outside temperature is (still) 99.

The A/C has been on (again, all day) and there’s almost no humidity, but just 10 degrees cooler? I expected better.

I’ve come to find the single biggest problem with Airstreams: a modern insulation system is non-existent. My model is a 2012 25′ Flying Cloud FB. It still has the pink fiberglass insulation which was tossed in Model Year 2013 for some more environmentally friendly insulation. My guess would be it likely performs about the same as any improvement would¬†should have been heralded by Jackson Center.

Starting in January when I moved in, I’ve used to good success 24″ x 10′ sheets of foil-backed bubble wrap branded Reflectix. I use it primarily in the windows and ceiling openings where it really makes a difference.

Interior wall next to the window (in sun)

Interior wall next to the window (in sun)6" to the left behind Reflectix and the curtain

6″ to the left behind Reflectix and curtain

The temperature at the interior wall (12″ from my head) is 98 degrees. With the Dometic 13.5k A/C running since 8:00AM. Yeah, I know.

The sun is low in the sky and it’s 99 degrees according to NOAA. The wall, on the inside where it has been cooled since 8:00AM, and being signed off as insulated by the Airstream factory, is 1 degree cooler. Yikes.

Move the temperature gauge 6″ to the left and it hits the curtain by the panorama window which, like the wall, is in direct sun. The difference is the window has little insulation factor, but there’s a sheet of Reflectix between the window and the curtain. The temperature reading is now 86 degrees. That’s 12 degrees cooler for Russ’ Relectix and only 1 degree for Airstream’s system.

It it wouldn’t look so silly, I’d be tempted to cover the entire inside of the trailer in Reflectix!

I wish I could order a Flying Cloud with that bubble wrap instead of the factory solution. That would be slick.

And I have a plan for the factory Dometic 13.5k A/C that’s only been used for 30 hours…