RV Floor Vent

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Ventilation in a Recreational Vehicle is of utmost importance in a constant fight against humidity and condensation. It is even a bigger issue while boondocking, and where air-conditioners don’t work.

temporary duct storage

The basic options you have is opening your windows and the use of a roof vent, to increase airflow throughout your RV. That has become more difficult for van owners, as the windows of many of the new European vans are fixed and don’t allow ventilation.

We strive to enhance natural convection in the RV, where airflow is induced by temperature and height difference and distance between air entry and exit points. Introduction of a floor vent in combination of a roof vent, could enhance the airflow substantially, even without mechanical means.

The vent would be situated at the opposite end of the vehicle, at a maximum distance from the roof vent, close to or in the floor, preferably in the center of the RV, where outside summertime temperatures are coolest.

Leaving both vents open, even while you’re away, could bring the excessive heat during summer, down close to the ambient temperatures outside the vehicle.

RV Floor Vent

Considerations

To induce natural convection, the location of a floor vent should be at the greatest distance from the roof vent. In my Ford Transit LWB, I choose the rear center of the roof as the place to install the roof vent; the location after the last cross member offers just enough room to fit a standard vent. This automatically forces me to locate the floor vent towards the front of the vehicle. Sometimes roof ventilation is in the front of the RV; a floor vent should then be placed towards the rear. Avoid any chance of toxic fumes from entering the vehicle; p.e. a location near the vehicle’s exhaust pipe is not safe.

floor vent location inside the wall
alternative location for a floor vent

Besides in the front center (where a vent would interfere with foot traffic between the cabin and the living area), I have three good options for installation. The entire length of the step-in area, immediately behind the passenger seat: this offers easy access to the area underneath the vehicle, but is in full view when you enter, exposed to dirt and it may interfere later on with the placement of water tanks under the van.
Close to it, is a small area at the very left, under the floor overhang that lends itself to it, but being closer to the rear vent may negatively influence the convection flow.

air entry location under vehicle

Ultimately, I choose a location behind the B-pillar, inside the wall cavity. This wall will be covered with a Murphy bed with an opening where the air can enter the living area.

Within the wall, a 10-15 square inch (50-100 square centimeters) area of the floor will be removed, to give access to an existing ‘porthole’.

With some effort, an ordinary 4 inch (10 cm) dryer duct will fit the cavity and the bottom opening and be covered with a ‘bug/rodent’ screen.

The duct seems fragile, but actually is quite sturdy and will be connected to the screen with a connector, made out of two pieces of aluminum flashing. One will fit over the duct, the other inside and they will hold the duct in place. The screen is made out of a piece of gutter screen, sized to fit the opening. The wall cavity will be filled with insulation at a later time.

The other end of the duct will be installed during the installation of the bed, with a manual ‘blast gate’ that can stop the airflow. At that time, a decision will be made if a small fan should be included in the setup.

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Materials

Aluminum Foil Dryer Vent Hose

79″ x 4″
Silver

Aluminum Flashing

6″ x 10″
Mill Finish

Gutter Guard Mesh

6” x 20′
Does Not Rust

Rusty Metal Primer

12 oz
Stops Rust

Painter’s tape

3pk
1″
60yd

Tools

Wheel Chock

Camco
Pack of 1
Yellow

DeWalt Drill

8.0-Amp
3/8-Inch
Corded
Variable Speed Trigger

Hole Saw Kit

17-Piece Hole Saw Set, 3/4″ to 5″ Hole Saw with Mandrel for Wood, Plastic and PVC.

Metal Hacksaw

12″ Blade
Wing Nut Tension Control

Drill Bit Set

13 Pcs
1/16″-1/4″
Hex Shank
High Speed Steel

J-Roller

13″ x 3″ Roller Size

Mill Bastard File

File Set
Single Cut
8″

RV Floor Vent Installation

Optional – Read through and understand this entire project first

In this project, I’ll show you my solution in my 2016 Ford Transit. With some modifications, the idea should work for other vans like the ProMaster or Sprinter as well or in any other RV. I’ll be cutting into my vehicle, which may have consequences for the van’s warranty or even worse. Make sure, that you know what you’re doing or consult an expert!

Gather all the tools and materials before proceeding. Regularly fit the materials, to avoid costly mistakes. Always use wheel chocks and secure your vehicle, when working under the van.

  1. Take measurements at all locations and be sure that all components will fit.
  2. Verify if you can access the wall cavity. Every make AND model has different specifications.
  3. Inside the wall, locate the opening and drill a pilot hole for the hole saw as far forward as possible.
  4. Follow up with a hole saw. I use one with 1-1/4 inch diameter.
  5. Verify the location of the hole from the top and from the bottom.
  6. Make an oval template of the duct, that still fits the depth of the wall cavity.
  7. Place the template in the wall, starting at the beginning of the hole and backwards.
  8. Drill another hole at the other end and as many as possible in between to remove most of the waste.
  9. The wall is narrow and I used a hacksaw blade to remove the remainder. If you can fit it in there, an oscillating multi-tool may be easier.
  10. A metal file smooths all the edges.
  11. Use some coarse sandpaper the remove the brim underneath.
  12. Paint the exposed metal to protect against rust.
  13. The depth to the exit screen is about 8 inches. Mark the extended duct at 12 inches.
  14. Flatten the end of the duct to about 3-1/2 inch. The depth of the wall cavity.
  15. Insert the duct up to the mark.
  16. Flatten the two pieces of aluminum flashing.
  17. Measure the size of the entry hole.
  18. Mark each aluminum sheet and cut to size.
  19. Mark the diameter of the duct onto the aluminum pieces.
  20. Mark an inner oval at about a 1/4 inch distance.
  21. Drill a wide hole in the center of both pieces.
  22. Cut along the inner line of one piece.
  23. Cut ‘tabs’ to the inner line on the other.
  24. Shorten the tabs.
  25. Cut the wire in the duct at 360 degrees, forming one circle.
  26. The first piece fits around the duct, the second fits inside, with the tabs folded in.
  27. Create extra hooks on the tabs, by bending the end of the tabs inward.
  28. Cut the screen to size.
  29. Pre-fit the screen.
  30. Mark the screen, where the bolts are inserted.
  31. Copy those holes to both aluminum pieces. Be aware, they fit only one way.
  32. Drill the holes in the aluminum.
  33. From underneath the vehicle, pull out the duct.
  34. Fold the excess duct foil inwards.
  35. Slide the first aluminum piece over the metal ring at the end of the duct.
  36. Then add the one with the tabs.
  37. Add the screen and bolt everything to the frame.
  38. Store the other end of the duct inside the wall until you’re ready to install.

materials

  • 4” Flexible Foil Dryer Duct
  • 2 Aluminum Flashing
  • Gutter Screen (min. 4” x 5.5”)
  • 2 Bolts, Washers and Nuts
  • Paint
  • Painter’s Tape

tools

  • Wheel Chock
  • Drill
  • Narrow Drill Bit
  • Wide Drill Bit
  • Hole Saw
  • Hacksaw or Oscillating Multi-Tool
  • Metal File
  • J-Roller
  • Pair of Pliers
  • Pair of Scissors
  • Sandpaper
  • Tape Measure
  • Marker

Conclusion

Only a few cheap materials are needed and most of you can do this work. Cutting into the frame of a (new) vehicle may or should not be so appealing to some. Only proceed if you know what you’re doing.

The duct, flashing and gutter screen used during this part of the project, were acquired locally and the total cost was about $14.45.

QUESTIONS, SUBMISSIONS OR CORRECTIONS

The missing parts of the complete van conversion process are being added regularly to this Build Guide. If you want to suggest a specific build option for this guide, submit a content correction or have a general inquiry, send me an email.

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Disclaimer: Throughout this guide, all guidance, building techniques and other information are based on my own experiences of converting a cargo van into a Tiny House on wheels. This guide is only for informational purposes; always build according to local and national standards. Be aware that such a project is expensive, requires a substantial amount of broad knowledge of building techniques and involves more work hours than you can imagine. Besides of hitting a finger with a hammer, much more serious harm can be done when you work with 12V/120V electrical systems, propane installations, power tools, etc. Tapping into the vehicle’s own systems can also damage its functionality. Get professional help where needed; never take any risk!