Boler DIY Power Roof Vent
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Boler DIY Power Roof Vent

Power roof vent that is both low draw and very quiet.

I wanted a fan in the roof vent but I find the Fantastic fan is too noisy and draws way too much battery power so I decided to build my own.

Very simply I used two 140mm computer case fans, each of the fans has 2 speeds, very low current draw and are almost silent.  The installation was simple, using 2 lengths of 1″ flat aluminum that is available in 8′ lengths at any hardware store I connected the fans to the strapping and then the strapping to the existing vent shroud using #8 machine screws.

The fans I used and their specifications are:

• Antec TrueQuiet 140

• Current draw – 0.04 amps on low and 0.1 amp on high

• Decibels – 9.8 db on low and 20 db on high

• Airflow (CFM) – 40.5 on low and 65 on high


Compared to the Fantastic fan (3 speed):

• Current draw – 1.89, 2.29 and 3.0 amps on low, medium and high

• Decibels – 39.0, 39.0 and 40.0 db on low, med and high

• Airflow (CFM) – 478, 653 and 920 on low med and high (no comparison on airflow but remember our trailers are only 360 cu/ft total volume without cabinets)


So how does it work?

We always travel with a portable weather station which displays and records temperature and humidity both inside and outside. Without the fans the interior was always hotter and had a much higher humidity than the outside, in fact in the mornings the humidity was often in the low to mid 90% range and the windows would be fogged up.

On last weeks trip to Glacier Park we used the fans, the interior temperature and humidity stayed either equal to or lower than the outside air and no window fogging or damp walls. A huge improvement. Even with both fans on high speed they were totally quiet, we could not hear them running even during the night.

I would recommend this addition to anyone’s trailer.

9 Responses

  1. cramar
    | Reply

    Great data on using computer fans. Just a superb idea. Enjoy your blog, and looking forward to more Boler and travel posts. Keep up the good work. Love the “prancing moose” logo. Now that is a fantastic Canadian original!

    The one suggestion is that this blog needs a separate link for sending a message to you. It took me a while of searching before I found the “Reply” areas.

    • Admin
      | Reply

      Thank you Cramar for both the comment and the suggestion.
      There is stall a lot of work to do on the website and I will follow-up on your suggestion to make it easier to find my email.

  2. Barbe
    | Reply

    Ian, this fan unit you’ve created looks like it would be much preferable to purchasing & installing a fantastic fan in my ’72 Boler. Unfortunately I don’t have your knowledge or skills to make such a nifty unit. Thank you for your generosity in sharing your restoration projects, problem solving and ideas on your website and through your many posts on the various Facebook sites. You need to patent this fan unit and if you ever sell them, I’d be first in line!

  3. jessie
    | Reply

    We have been looking at the power vents. I am sure this is going to be our alternative plan! thank you!

    • Ian G.
      | Reply

      Glad this was helpful. The great advantages of this design is the very low battery draw and it is extremely quiet.
      We really love the way it works.

  4. Vic
    | Reply


    I like the computer fan idea very much. Question about availability and switching.

    Does a guy go to a computer wrecking yard and get two of these babies for free or must we live in a huge metropolitan area and purchase them across the counter for probably $40.00 apiece? Please don’t take this as sarcasm but I really have no idea where I could obtain these fans living in a small city like this. Perhaps the ReStore might have some?

    Next question: You mentioned two speed. Are there specific switches that can be had or purchased to accomplish this feat? Are they available on a computer as well?

    Thanks for your reply


    • Ian G.
      | Reply

      I bought the fans new through a computer supply store (Memory Express), I believe I paid $17.00 each for them. But used fans would also work equally as well.
      The specific fans I mention and used are a 2 speed fan so they have a switch built into them to control the speeds, this is an option, as single speed fans would work great.

  5. Dan
    | Reply

    Silly question, but do the fans blow air in the boler or suck the air out of the boler?

    • Ian G.
      | Reply

      The fans blow the air out of the vent (my logic is that hot air rises)

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