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SJ-Chris
Explorer II
Sep 20, 2022

Custom RV Vent Fan Project

Custom RV Vent Fan Project

Summary: Custom roof vent fan created that is very quiet and very low power, and also works on vents that do not have a crank to open/close the vent (but rather has the pull open/closed levers). Sound and power analysis is down at the bottom.

I wanted to add some vent fans to some of my RVs. Specifically, I wanted to add fans above the bed in the rear of the RV. I love bringing in cool air at night and while sleeping, especially when camping in the summer heat when it finally cools down in the evening. The ceiling vents on one of my RVs doesn’t have a crank handle, but instead has one of these push/pull levers…


So that seemed to eliminate the possibility of many of the full vent sized fans (ie. Heng’s Vortex, MaxxAir, etc) without doing perhaps more work than I wanted to do to redo the vent.

I also had two other criteria that I really wanted to see if I could achieve… Quiet and Low Power.

I decided to build my own fan solution just to see if I could do it (…I enjoy these type of projects). After researching quiet, low power, 12v fans, I landed on this one…


https://www.amazon.com/gp/product/B08QDMV4X6/
$12.37 on Amazon. It is actually a fan made to cool computers. Airflow: 72.8 CFM/123.76 m³/h (@ 1700 RPM), Noise Level: 0.3 Sone (@ 1700 RPM). Very quiet. For each vent, I put two of these together.

To connect them, I got some ½” aluminum angle bar from Home Depot and drilled some holes in the appropriate places to attach the fans (Cost ~$2.50 for this setup length needed). I painted them glossy white on the underneath visible side…


https://www.homedepot.com/p/Everbilt-1-2-in-x-96-in-Aluminum-Angle-Bar-with-1-20-in-Thick-802677/204273980

I wanted to have a nice clean finish, and I had some white gloss Rustoleum spraypaint already so I spray painted the bolt heads…

(I drilled a bunch of little holes to “hold” all the screws upright while I spray painted them)

Then I put two fans together…




Here is the top side of the fan assembly (unpainted because you cannot see it from inside the RV) next to a Heng’s Vortex I had laying around.


Here is what it will sort of look like when installed in the non-crank vent (screen not put back on yet)…


I decided to put it on one of my other RVs first (one that does have a crank to open/close the vent)…

From this…


To this…


I was lucky to find power right at the vent when I took off the trim, so that made wiring it up easy. I added a switch ($4) to turn it on/off:


When I was installing everything, I damaged the screen…and it is a bit dirty. So I ordered a new one and new white trim as long as I’m at it. Should be able to install those in a few days once they arrive.

So how does it work, sound, and how much power does it use?? I tested/compared 3 fans that are in this RV.

Fan #1: Not sure the brand, but it is like a Heng’s Vortex, or MaxxAir, or Fantastic Fan.
Fan #2: Your standard bathroom 6” propeller fan.
Fan #3: My custom designed fan.

Fan #1:


Fan #2:


Fan #3:


Noise Test:
Fan #1: (it has 3 speeds) Low: 23dB, Medium: 26.8dB, High: 28.8dB
Fan #2: (bathroom fan): 30.7dB
Fan #3: (my custom fan): 10.4dB (Very quiet)

Power Test: (via a battery monitor)
Fan #1: Low: 1.08a, Medium: 1.44a, High: 1.88a (it has 3 speeds)
Fan #2: (bathroom fan): 1.2a
Fan #3: (my custom fan): 0.25a (4 times less than the big fan on Low speed)

Air Flow test:
Fan #1: Only blows out (not reversible): Seems to move a tremendous amount of air. I read somewhere for similar types of full vent fans blowing ~170cfm.
Fan #2: (bathroom fan): Only blows out: 6” fan. Couldn’t find the CFM spec.
Fan #3: (my custom fan): The ad description says 72.8cfm per fan. So two fans might be 145cfm(?). It does blow a decent amount, but I feel like it is a fair amount less than the full vent Fantastic Fan type.

Summary: My total cost was ~$40 for the parts. It was pretty easy to put together and to install. I’m VERY happy with how quiet it is and how little power it consumes considering I will likely leave this on overnight while sleeping. It also will allow me to add fans to the vents that do not have the vent cranks on them (so a Vortex or Fantastic Fan or MaxxAir would not work). I especially think I’ll be adding these over the rear beds of my other 2 RVs since they are so quiet. I have solar on all my RVs, so while the RV is in storage I might just leave the fan running (0.25amp x ~12hr of darkness = 3AH from my battery bank) pulling in fresh air (I have a vent cover over this vent so I can keep it open even if it is raining or while driving).

Stay breezy!
Chris
  • Nice job. I bought a couple of those 12V weatherproof fans from Amazon for $19 and am going to put them behind the fridge. We have a fantastic fan over the bed and have been using it every night now the weather has cooled down.
  • I had the opportunity to try out this new ceiling fan over 4 days of boondocking at King's Canyon & Sequoia National Park this last weekend. It did a decent job bringing in cool evening air and was VERY quiet (...kept it running at night).

    It doesn't bring in high volume of air (like a Heng's or MaxxAir), but you can feel it while laying down and it is very quiet which was my goal (...also just ~.25amps so very little battery use).

    I will be adding another to one of my other RVs that has the pull handle open/close mechanism instead of the crank as it is a particularly good option for that situation.

    Keep cool all!
    Chris
  • Nice job SJ!

    H'mm, this may do the trick for us too when we boondock. We only need a little air moving to make a difference over the bed where there is a standard 14 x 14 vent. I do not like strong wind blowing over me and then there is the noise issue.

    I have a 3 speed Maxx Fan in the next room on a T stat that we do use while boondocking, but with the power draw, I do not want to run it all night, your upgrade may be just the fix we are after.

    Thanks for sharing.

    John
  • Finally got around to adding another custom fan to another one of my RVs. This is the RV vent that motivated me to create a custom fan because it has a different open/close mechanism.

    Here's the pic of the fan installed:


    Stay cool!
    -Chris

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