*Safely* insulating a portable air conditioner's exhaust tube. How?

[Popsiclestix]

I assume this is one of those room units that exhaust through a cheap slingy type plastic tube outside? I have a 1 kW unit made by sharp in my room.

May I ask why you think the tube needs more insulation? Are you sure it is not just the sunlight shining directly on the temperature probe so that it is artifically inflating the temperature?

The VAST majority of expelled heat is carried in the moving air mass and very little is actually transferred to the exhaust tubing. I can go into first approximation calculations if you want, but I doubt you're getting even 5% reemitted back into the room. You're not likely to gain much by wrapping the exhaust tube of such a small unit.

It almost sounds like you have a leak somewhere along the tube.

 

[StarHalo]

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Original post is from April 2009
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[ElectronGuru]

At the risk of continuing...

All insulation has to do is keep air from moving about. Not all insulation is industrial, a pair of pillows on either side insulates all kinds of things.

But as has been suggested, this is not the problem. The machine is sucking in air from the room, heating it up, a blowing it out the exhaust tube. This action creates a vacuum in the room itself. To replace this air, "the room" will suck it in from the least sealed panel, door, or window. In this case, from the very window doing the exhausting - drawing hot air right back in.

Portable units should only be used when window units cannot be.

 

[andyw513]

I've heard of spray-foam being sprayed in it before, but I don't really think it is that great of an idea. We have adhesive-backed foam in ours and it works well enough.

On a 'light'er note, this thread reminded me of this past winter: This guy takes a Keystone Light box and insulates a pot-belly stove pipe with it...inside his house...and the pipe was ran out of a single-wide window.