Originally Posted by NJ Joe
Any concern with the air that enters through your new bottom vent getting sucked out the side vent when the trailer is underway ?
Good question. I won't really know until we take a long trip south in February. Hopefully I have built in the ability to make changes to optimize this air system.
I have thought a lot about the aerodynamics of the top and bottom vent. Some people complain of poor operation on the road and I wondered if there may be some backflow in the stock system.
We have hauled our trailer maybe 900 miles so far and always with the propane turned on with a digital thermometer inside that reads outside. Whenever we stop I have been looking at the temperature obsessively and I don't see any significant changes. I definitely see changes in ambient temperature will change frig temp and increase or decrease the 'power' (1-5 bars) to compensate.
That being said, I built the air box right inside the lower vent so I could fool around with the fan mount angle and design. The 'texas fan' was mounted up in the vent system at a location you would have to cut into the upper vent screen, or pull the refrigerator, to service.
The air box is simply a wooden box that I can slip in a piece of wood, or metal straps, to mount fan(s), create a baffle, or whatever. I was happy to find a protected area of 'disturbed air' for the lower pickup. IF air is sucked out the side vent but it doesn't affect the refrigerator temperature I don't care.
I have sealed all joints with tape, silicon, etc. to insure the air system is 'closed' from the living area. I would hope the Dometic top vent is designed to 'draw' air up the chimney and my additional lower vent should not increase the lower supply to greater then the upper outflow.
If the 3 air vents work unpredictably for any reason I can always add an aluminum sheet deflector to break the draw, but my guess is this will work better then what I had.