written 6/27/25, updated 6/27/25

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Materials and Cost

Optional: Removeable Window Sealing Tape (~$10-12)

Note: as of this writing, a dual hose window kit on Amazon will cost you about $33.99; from Home Depot is $37.18. However, you can also buy foam inserts that fit into them for $35.99 because, apparently, the kits don’t keep out heat as well as you’d think.

Owned Supplies

Process

Measurements

Orient the AC unit and figure out how hoses should be placed to figure out how much of the opening you’ll need to fill will the vent mount. Take your measurements which will tell you how much material is needed.

My window is 31″ x 58″ (W x H), with each opening about 28″. I’m working with an Ecoflow Wave 3 for which the hoses have 2 slightly different opening sizes. After orienting the machine and hoses for the space available, I knew that I needed the window to be open about as much as it can be.

NOTE: For a dual hose unit, try to place the exhaust hose higher than the intake hose since heat rises, and air under the hotter expelling air should be cooler. For a single hose unit, you won’t need to open the window as much

Materials

Gather any owned equipment, then procure necessary tools and materials (I ran out to Home Depot)

Note: My window has a screen, so I left it down and placed the vent hoses on the other side. If yours does not have a screen, it would probably be a good idea to factor in a mesh screen to prevent bugs entering the hoses when not in use. Products like Fiberglass Mesh Rolls, or Vent Mesh Rodent/Bird Screens are options.

Fitting

With supplies in hand, test the Rigid Foam Board on the window. Mine was best sitting inside the lip of the window jamb. If more material is needed, measure and mark with the Sharpie. Secure the foam board in place (either lower the window onto it, or use masking tape), then place each vent hose in its desired spot and trace with the Sharpie

Cutting

Time to make cuts! Depending on cutting location, make sure to put down a drop cloth, newspaper, or other covering for easy cleanup. The foam pieces will get everywhere

First off, I put together the main window panel by cutting the piece to make it whole using measurements (in my case about 8in). I used a Square and a Utility Knife to score both sides, then all that’s needed is a little bit of force to snap the piece off (I just used the edge of a chair for leverage)

Next are the holes! My Ecoflow happened to come with a Vent Hole Template, so I used Masking Tape to adhere that to each traced hole

I’m sure a jigsaw would be the easiest and cleanest way to accomplish this, but I wasn’t about to shell out another $200 for that (maybe at some point in the future).

So, I used a Utility Knife to cut the circular shape. Because the foam board was too thick for just the utility knife, I poked holes with a random tool (can be a screwdriver) and connected the lines with a Sharpie.

Then with the utility knife, I cut the round pattern and a cross pattern on either side to facilitate removal

At this point you can use any variety of methods to chip away at the foam (e.g. mallet, screwdriver, knife). I ended up using a Craft Knife to deepen the utility knife cuts all the way around, and it was excellent for smoothing out the holes

Mallet

Craft Knife

Assembly

Back upstairs! First up: making sure the main panel pieces fit into the window. Next, dry fit the hoses. Used the craft knife to make some adjustments.

Another dry fit of all pieces. Looks good!

Now to connect the two pieces of the main panel with the HVAC Aluminum Foil Tape. I’ve never used that kind of tape before. It’s like putting on a vinyl where you have to peel away the backing. When attached, the hold feels extra strong, so be careful not to rush and mess it up.

After another dry fit

Moving on: now to adhere the Double Reflective Insulation. This really is an optional thing, but I wanted to do this because manufacturer wording on the rigid foam boards notes that its only rated to 75F. Given the beating sun and 100F heat, I wanted something else to both block heat and afford a little more weather resistance to the panel.

Fun Note: The material is just like sunshades for a car. One of the favorite things I’ve ever bought are custom driver and passenger window shades for my car, and it literally uses the exact same material except with an edge liner to look pretty

To attach the insulator, use Masking or Painters’ Tape (painter’s is easier to remove) to adhere the material to the foam board, then cut to size. Then, use the HVAC Tape to secure it to the foam board.

Make sure you’re applying it to the proper side!

NOTE: This will add some width to the foam board, which isn’t necessarily a bad thing, but if it’s too tight, you may have to trim some off the foam. I left mine the way it was and just jammed it in there. It was a tight fit, but that works for sealing out weather and bugs. It is foam after all and will compress a little.

Cut the vent holes out with scissors. I left a little bit of excess material around the opening for a little more bug/weather barrier.

Later, I ended up securing each hole with 4 pieces of HVAC Tape because I realized that air movement might balloon out the space between the insulation and the foam board.

Finishing Up

We’re pretty much done at this point! Go ahead and place it all into the window, place all the hoses, and check out your handiwork!

The only thing left to do is to seal the cracks around the foam board and the vent hoses.

I used Masking Tape for easy removal, but if you want something better, buy some Removable Window Sealing Tape (XFasten brand on Amazon is $11.99, appears to be based in Florida).

DONE!

Notes

• The whole system works well, and removal is as easy as removing tape
• Sound is a problem, though. I can hear everything outside. Like birds in the morning. When you’re getting your best sleep. I considered some soundproof paneling to put in front of it but then realized that I don’t use the unit too much unless there’s a heat wave. Not only that, but the panels are pretty expensive.
• It also makes my room smell like an attic with all the outdoor smells. Perhaps it would be different if I’d used the Window Sealing Tape?

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