I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a window). Almost the opposite of what you normally do with a portable A/C unit.

I have an office right next to my LR and want to pump the A/C into my LR sometimes and other times into my office. Because I did not have a window to have my A/C Air come into my office through a hole we cut and placed and fit a flexible dryer vent pipe (the white floppy accordion style)through the wall and on the inside of my office I have the dryer vent cover with flaps (like you would normally see on the outside. This prevents and critters from getting in.

I am trying to figure out how to split the out flowing A/C air though a "dual Y pipe of some type to flow into my office when I want it in there and my LR when I want it in there.

IS there any such thing as a U pipe that is not rigid that I could use for this and also some how block them when I want it to flow in only one side or the other?

  • 1
    One problem you may face is that when used with the A/C unit outside of the room, the remote extender (which also contains the room temperature sensor) should be placed in the room being cooled. Without that sensor or remote control, there would be no way to control the temperature of the room being cooled.
    – Johnny
    Aug 13, 2015 at 22:35

3 Answers 3


While this is rigid, it is better for connecting flex pipe. enter image description here

  • And two dampers with two short pieces of 6" rigid to put them in.
    – Mazura
    Aug 14, 2015 at 13:59

First off, if you're using a cheap flexible vinyl tube like this.

Flexible vinyl tube

You're probably losing most of your cool air, before it even reaches your house.

Instead, you'll want to use an insulated duct. I'd recommend a rigid duct, but flexible duct is probably acceptable for this application. Something like this flexible insulated duct is probably acceptable.

4" Insulated flexible duct

To split the air, you'll need a wye.

4" x 4" x 4" wye

which if on the outside of the building, should also have to be insulated.

If you don't want to cool both rooms at the same time, you'll also want to install dampers. You can get manual dampers, which would require you to open and close them via a lever on the outside of the duct. If you really want to get fancy, you could install powered dampers, which would allow you to control them automatically via some type of control mechanism. Powered dampers controlled by a raspberry pi/Arduino might be a neat little project. While we're talking dampers. You'll also probably want a backflow damper somewhere, so the air in your home doesn't get pushed outside when the unit is off.

4" manual damper 4" power damper

While searching for photos for this answer, I stumbled upon a product that might work well for you. It's called a dual duct kit, and includes a wye, 12.5' of insulated duct, and a supply grill.

dual duct kit


Raid the parts bin for ducting for home shop dust collectors (vacuum cleaners optimized for sawdust). Typically they are 4-6” diameter, snap together and/or have flexible sections, and are plumbed to several machines. Each machine gets a guillotine style shut-off gate. The gate can be controlled precisely.

They also make automatic gates which open when current is detected flowing on a circuit (intended for a machine tool spinning up, but also would work for a PC coming out of sleep mode). You could use one auto-gate and one manual on the same branch, one for auto on-off and the other for fine control.

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