A Boler really benefits from a power roof vent, it helps cool the interior, controls humidity and condensation, and can be useful when cooking.

Below you will find two options each with its own advantages and disadvantages.

Option 1 – DIY Power Roof Vent


  • Inexpensive
  • Very low current draw (great for boondocking)
  • Very quiet


  • Need to fabricate fan mounts to vent
  • Lower air flow

This first option requires a little more work but I personally prefer it over the commercially available Power roof fans for two reasons:

  1. Noise – I hate the noise a fan makes, I wanted a power roof fan so quiet I could hear the silence of the forest while camping and leave it running all night and it would not disturb our while sleep.
  2. Power Draw – I didn’t wantto be concerned that leaving the fan on all day and night in hot weather would drain the battery

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.


Option  – Fantastic Fan or Maxx Fan


9 Responses

  1. Derek
    | Reply

    I was wondering if you could provide more detailed instructions on how you adapted the wiring of the fans to integrate them into boler wiring system.

    • Ian
      | Reply

      Hi Derek
      Wiring is very simple, connect the +power through a switch to the fan and complete the circuit by connecting the ground.

      • Derek
        | Reply

        Thanks for the response. I have placed an order for the antec 140s, so I may get in touch with you when they arrive with more questions (if that’s alright with you) as I have no experience with wiring. It looks like some stripping of wires might be required as the connections appear to be tailored specifically to a computer power source. Is this true?

      • Gerrie J Schalkx
        | Reply

        I hooked up the 2 fans but they seemed to have quit right away. They wont turn back on. Could they have burnt out? That’s what it seems like. Are they made to work on 12 volts or should they be hooked up in series so they use 6 volts each?

        • Ian
          | Reply

          Hi Gerrie. To my knowledge computer fans are 12VDC which means they would be wired in parallel but you should always double check the voltage of the fan to make sure. Always trouble shoot to find out the problem. First test to make sure you have power (12VDC) to the fans. Then make sure the ground circuit is working, these can all be done with a multi-meter testing total power, voltage drops and resistances. I would also use jumpers to wire the fans directly to test them as a final step.

  2. Ted Kereluk
    | Reply

    Curious what you used for switches and where did you put them ? I ordered these fans and supplied switches are tiny. I’d rather have a 3 way toggle or some other switch wall mounted

    • Ian
      | Reply

      I connected the two smaller fans on one SPST switch and the large fan to a separate SPST switch, this allows the fanes to be operated independently. 2 small for low, large for medium, and all 3 for high. I used small RV style on/off rocker switches locate under the kitchen counter.

  3. Ted Kereluk
    | Reply

    Hi Ian, I bought these fans and vent, where did you mount your brackets besides the center bar ?

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