Sun-Mar 12V DC 4in. Vent Fan


  • 12V DC composting toilet vent fan
  • Improves airflow in Non-Electric toilets
  • Installs easily in 4 inch toilet vent pipe


The Sun-Mar 12V DC vent fan is pre-installed in a section of 4″ vent pipe. If you are installing a non-electric composting toilet, this fan will easily mount inline with your vent.

The Sun-Mar vent fan is a required accessory in certain composting toilet installations:

  • if you have to put any bends in the vent stack (Sun-Mar recommends no more than two 45 elbows, even with a 12 volt fan installed)
  • if your installation location is subject to downdraft
  • when using an AC/DC model toilet with both vent stacks installed

The 12V fan is a recommended accessory in other installations:

  • if the unit is being used residentially
  • if you expect heavy seasonal use

(A 12V fan is included with the Centrex 3000 NE, and does not need to be purchased separately. While installing the fan is not required with the 1000 or 2000 NE models, it is strongly recommended.)


Choose a section of your vent where you will easily be able to access the fan. Cut a suitably sized section of vent stack and insert the fan into the stack, ensuring that the piece is positioned correctly so that the fan is blowing upwards (coupling will be at the bottom). Caulk both seams with silicone for the best airflow.

You can attach the fan directly to a 12V battery (which should have a power source to charge it, such as a solar panel or other alternative energy source), or use an AC adapter of the correct wattage. If you’re using an AC adapter cut off the female plug, attach the positive adapter wire to the red fan wire, the negative adapter wire to the blue fan wire, and secure both with small wire connectors. Plug adapter into wall.

Additional information

Weight5 lbs