Roof mount exhaust fan vs wall mount on sides of food truck

Since I too am doing all the necessary research on a concession trailer build, I have been reading all of the related threads and taking notes. Does anyone care to post negative/positive results with their type of exhaust fan setups (vertical/horizontal with/without makeup air...etc)?

To start with you need to keep in mind the overall height of your truck or trailer. And not just for highway use but for city driving as well. Most cities don't trim tree branches that hang out over streets and instead depend on semi trucks to clear low hanging branches. So semi drivers drive in the center lane when possible which means the curb lanes have lots of tree branches that will beat the heck out of your above exhaust fan housing and when it gets dented it loses some of it's designed swirl exhaust ability.
jack

Good points Dr of BBQ.

Keep in mind what ever system/equipment installed, it will need cleaning to remove buildup of grease from the inside of duct & fan. Slope any duct work to drain into a grease collection can or to the outside.    ... Yes the ducts are very short in a truck ... usually.   So make any access needed easy so cleaning will not be a 'dreaded chore'.

Someone on here not to long ago built a truck and we talked about where to get the fans like the food trucks used.I forget where he said. but search this forum and you'll find it.

Thanks edwmax, ease of upkeep is paramount.

 
This is the system I am using for my exhaust at the back of my rig. The metal fan motor mounts have since been painted, and the fans wired up with their switches at the front of the rig.
The next step is the custom hood, which is being fabricated locally. These fans (12v) move plenty of air and I imagine I will only need them on low. I'll have a 3' propane griddle next to a propane steam table at the back.
 
I too was not interested in a vertical exhaust setup. Mostly because the fan systems are all AC power and I wanted 12v power for everything. But also because of the aesthetic of a huge fan on top of a moving truck. I did some research and saw some wall mount exhausts and that gave me the confidence to proceed with this custom job.