HI Richard,You are discussing peamnrent set ups, which have quite a different focus and what you are suggesting is depositing straight into a larger chamber, opposed to buckets that can be emptied for composting.In a more peamnrent set up, a vent pipe is very beneficial. Metal is good to conduct heat better, painting black is also beneficial. Attaching a small computer fan, (which are all 12v) to the pipe is also I have set up in areas where airflow is restricted (i.e. wet damp frosty locations in the middle of winter). The fan can be attached easily directly to a car battery and draws VERY little energy.The pipe is best tapped into the highest point possible and if you vessel/chamber underneath is large enough, you can have it next to the toilet seat at the same level.many systems you buy have shoots to deposit through, with the chamber below. This is great for regulations to ensure deposited material is not able to build up to a height that is near to ones backside. However, because the deposited material mounds up under the shoot, heat, moisture all rises up the shoot and condensates under the seat. In this circumstance it is important to have the vent coming off the top of the shoot, rather than the chamber. This is a design problem I have seen with many systems, especially not fan assisted.So vents need to be at the highest possible location.Another tip on this front is to use the off cut where you cut out the hole for the toilet seat and put a backing piece of timber on it, larger than the off cut to create a plug. So in-between deposits use this instead of putting the seat down. Any condensation that might occur, (if the system is not vented properly) will occur on the plug, rather than the underside of the toilet seat.Lastly, I suggest having this type of toilet system on the south side of a dwelling, or in a shaded location. This reducing the composting happening while the chamber is in place and leave the composting upto the phase when it is set aside. This reduces heat build up and again condensation levels.I have set up a variety of sealing systems, the best being old seals for car door frames. It fits perfectly over the lips of many containers.Anyway I hope this helps some what Richard. I could go on a lot about this, but is hard on a keyboard opposed to in person. Great discussion points though.Thanks.James

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