I had the idea that the air near the ground under the van should be cooler than the air coming in my Fan-Tastic roof fan. So I drilled a hole in the floor to suck the air up, and reversed the direction of my ceiling fan to blow the air out at the top instead of bringing it in.
I am truly astonished by how much difference that has made! I'm so much more comfortable inside my van now, even when it's near 100F outside.
Drilling a large hole in the floor and reversing the ceiling fan to blow air out, might be enough for your rig, but I got fancier. Here is my so cool (pun intended) layout:
1. I cut a hole through the floor the right size to place the end of a 4" bilge fan into it.
2. I bought this 36"X84" role of Standard Window Screen (originally to keep bugs from coming through my windows, but it is great for this purpose too). Soft and flexible, it was easy to cut with scissors to the right size to cover the hole in the floor plus a couple of inches more on each side since I will press it down into the floor with the fan.
![Image 8.jpg Image 8.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37014-57822bfe7fd9b407e24be012273ce4ea.jpg)
3. On top of this goes my 12V 4" in-Line Marine Bilge Air Blower which I pressed snuggly down into the drilled hole, securing the window screen as well.
![Image 6.jpg Image 6.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37015-af407ad6c9fcedd6af3ee00ee1ea5551.jpg)
4. The fan inside the Bilge Air Blower is really noisy. I used this vehicle door/floor/wall surface sound deadener (which quiets the sound down quite a lot). The backside of the material is very sticky after you peal off the protective paper, so it was easy to coat the entire outside of the bilge fan with the stuff. This also helped make the bilge fan fit snuggly into the hole.
![Image 9.jpg Image 9.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37016-71e5189622a2315ad8f900a3a22cee76.jpg)
5. The wires from the fan go through this Waterproof Junction Box in which I installed this 15A DPDT 3-position switch. The switch is wired so that if flipped up, the fan sucks the air up, and if switched down, the fan blows the air down and out of the van. Of course, the middle position is off. And be sure to put a fuse on it! (The fan seems to pull about 6 amps, but the start current nears 15 amps, so the fuse needs to be for 15 Amps.) And of course, all your electrical circuits should be fused for safety. (Like Smokey the Bear used to say, "Only YOU can prevent van fires.")
![Image 4.jpg Image 4.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37017-2bdcffefd601c2f1e5961f650f3b8159.jpg)
![Image 3.jpg Image 3.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37018-f1cc581b1268bc095925625e82c8f184.jpg)
On top of the bilge fan goes the six-inch diameter duct, which I lined with this one-inch acoustic foam. The foam reduces the 6" air path inside the duct back to the 4" diameter of the bilge fan (hence, the reason for using a six-inch diameter duct). I cut the duct to a length of only two feet so it would stand straight up under my desk while active on top of the bilge fan. That deadens the noise coming up from the bilge fan really well. All I hear coming out of the end of the duct is the rush of air.
![Image 1.jpg Image 1.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37019-2b6a793caa97956ed0551375fd35028e.jpg)
![Image 2.jpg Image 2.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37020-1535602af5eb490b3467a78403365db1.jpg)
To my surprise, I seldom need to run the bilge fan because the ceiling fan pulling air up through the bilge fan and duct does the whole job quite well.
CAUTION: Having both the engine exhaust blowing out carbon monoxide under your rig, and this hole in the floor drawing in air from under your rig can be deadly!. Never do both at the same time! It is best to keep the hole in the floor covered while the engine is turned on. And to start with, cut the hole in your floor well forward of the exhaust, and on the opposite side from the exhaust. Be safe, be healthy, and stay alive!
I am truly astonished by how much difference that has made! I'm so much more comfortable inside my van now, even when it's near 100F outside.
Drilling a large hole in the floor and reversing the ceiling fan to blow air out, might be enough for your rig, but I got fancier. Here is my so cool (pun intended) layout:
1. I cut a hole through the floor the right size to place the end of a 4" bilge fan into it.
2. I bought this 36"X84" role of Standard Window Screen (originally to keep bugs from coming through my windows, but it is great for this purpose too). Soft and flexible, it was easy to cut with scissors to the right size to cover the hole in the floor plus a couple of inches more on each side since I will press it down into the floor with the fan.
![Image 8.jpg Image 8.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37014-57822bfe7fd9b407e24be012273ce4ea.jpg)
3. On top of this goes my 12V 4" in-Line Marine Bilge Air Blower which I pressed snuggly down into the drilled hole, securing the window screen as well.
![Image 6.jpg Image 6.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37015-af407ad6c9fcedd6af3ee00ee1ea5551.jpg)
4. The fan inside the Bilge Air Blower is really noisy. I used this vehicle door/floor/wall surface sound deadener (which quiets the sound down quite a lot). The backside of the material is very sticky after you peal off the protective paper, so it was easy to coat the entire outside of the bilge fan with the stuff. This also helped make the bilge fan fit snuggly into the hole.
![Image 9.jpg Image 9.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37016-71e5189622a2315ad8f900a3a22cee76.jpg)
5. The wires from the fan go through this Waterproof Junction Box in which I installed this 15A DPDT 3-position switch. The switch is wired so that if flipped up, the fan sucks the air up, and if switched down, the fan blows the air down and out of the van. Of course, the middle position is off. And be sure to put a fuse on it! (The fan seems to pull about 6 amps, but the start current nears 15 amps, so the fuse needs to be for 15 Amps.) And of course, all your electrical circuits should be fused for safety. (Like Smokey the Bear used to say, "Only YOU can prevent van fires.")
![Image 4.jpg Image 4.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37017-2bdcffefd601c2f1e5961f650f3b8159.jpg)
![Image 3.jpg Image 3.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37018-f1cc581b1268bc095925625e82c8f184.jpg)
On top of the bilge fan goes the six-inch diameter duct, which I lined with this one-inch acoustic foam. The foam reduces the 6" air path inside the duct back to the 4" diameter of the bilge fan (hence, the reason for using a six-inch diameter duct). I cut the duct to a length of only two feet so it would stand straight up under my desk while active on top of the bilge fan. That deadens the noise coming up from the bilge fan really well. All I hear coming out of the end of the duct is the rush of air.
![Image 1.jpg Image 1.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37019-2b6a793caa97956ed0551375fd35028e.jpg)
![Image 2.jpg Image 2.jpg](https://cdn.imagearchive.com/vanlivingforum/data/attachments/37/37020-1535602af5eb490b3467a78403365db1.jpg)
To my surprise, I seldom need to run the bilge fan because the ceiling fan pulling air up through the bilge fan and duct does the whole job quite well.
CAUTION: Having both the engine exhaust blowing out carbon monoxide under your rig, and this hole in the floor drawing in air from under your rig can be deadly!. Never do both at the same time! It is best to keep the hole in the floor covered while the engine is turned on. And to start with, cut the hole in your floor well forward of the exhaust, and on the opposite side from the exhaust. Be safe, be healthy, and stay alive!
Last edited: