Ventilation experiments

Yesterday I triedan experiment with my ventilation fans. I reversed them. Within a few minutes, cool air had flooded into the back of the bus together with choking amounts of pollen. That wasn’t so good! Having said that, it did prove that the mosquito mesh is too small and too restrictive. I have a flat mesh over a plastig grill on the end of the ventilation duct. Beyond that are my mushroom domes.

Experiments earlier in the year proved that the mushroom domes and the mosquito mesh were reducing airflow by about 40%. It uses more energy for the fans to push air through a constricted duct than to pull it out of a constricted duct.

Since in one of my earlier experiments I found that removing the plastic grill and replacing it with just a mesh increased airflow from 1400 FPS to 1500 FPS, I was determined to find a way to increase it further. Clearly as the wire of the mesh takes up space and therefore a percentage of the air, it was important to have something that wasn’t flat. Something convex or concave as the mosquito mesh.

I tried, to make a dome covered in mosquito mesh but it was not a success because mosquito mesh is flat, not convex. That put me on hold for a while. I’d found that the louvered vents had their own issues with not closing fully every time.

The louvered vents claim to be paintable. I’ve tried oil paint, latex paint and now paint that claims to be good for plastic. Nothing thus far seems to be adhering all that well. Despite that I’m plugging on with my mission to improve ventilation.

One though I had was to put the louvered vents up and a stainless steel sieve over them. Indeed, I bought a sieve but then when I was in Walmart I also saw sink strainers. The mesh is slightly bigger but not that much bigger. The wonderful thing about them is that they’re concave. Their concavity more than makes up for the obstruction to airflow posed by the wires.

Thinking on the outlets, I did buy some aluminum disks of 3” diameter to go into my 3” piping, together with a hinge so that airflow would blow the disk out of the way and gravity would bring it back. Sadly it seems that the 3” disks bought on ebay are actually undersized while the tubes are slightly oversized. That made that idea a fail as there’s no way to prevent critters entering past the disk.

The solution (on the inside of the bus) is to put a 3inch to 4 inch converter on my exhaust fans then the sink strainer on that. It’s all glued with some stuff called “Liquid Nails” so I’ll have to see how good that is and how long it all stays together. This is the belt and braces approach as on the outside I will have my louvered vents.

Putting the louvered vents on could be challenging since I cut the plates that the tubing comes through to be hexagonal. I’ll have to cut some plexiglass to fit to square it all, insert some rivnuts into the bus so the vents can be mounted then hope and pray that the paint stays on them. The vents should stop backdraft, water ingress and bugs getting in. If they get past the louvered vents then when they reach the sink strainer, that’ll stop them. Those in the system will just get blown out. I will just have to see how it works.

In other news, I have some elastometric paint. That’s going to get painted on the roof after I give the roof a quick wash with my industrial cleaner. On the tin, it claims to reflect 67% of the heat and sunlight. I’m very dubious hence I bought just one tin. That should be enough for most of the roof. The ordinary white paint I put up there worked phenomenally well. I doubt this will work that much better but it’s worth trying.