Has anyone tried to duct inside air to the intake of the stock auxiliary 
heater fan that hangs over your engine ?

I'm thinking about committing all heat to the front of the bus and using 
the heat ducts under the back seat and between the backs of the front 
seats as return heat vents.

And if I were really slick, I could use the heat directer box thingy that 
was previously meant to control the flow of heat to the front or to the 
rear of the bus for selecting between "fresh air" heat or recirculated heat.

Did anyone understand that Friday stream of consciousness???? OK, here 
are the steps I'm proposing:

1) Remove the heat direction box underneath the bus and replace with one 
continuous tube (dryer venting, pvc pipe, abs pipe, 
insulated: whatever's best.)

2) The just-removed heat direction box has two big openings (to the 
engine and to the front) and two smaller openings (one ducted to a vent 
between the front seats and the other under the back seat.) Leave the two 
smaller ducts connected and duct the output end of the box (the one that 
was attached to the front duct) to the intake of the heater fan above 
your engine. (I haven't figured out how to do this yet...)

3) And to be slick...cover the intake of the box (what used to be ducted
to the engine) with a screen and position it that you can get maximal
fresh air and minimal road splatter.  Now, the cable on your dash is no
longer a "rear heat/defrost" switch:  it's a "fresh heat/recirculated
heat" switch. Actually, I think there are a few cables hooked to this
lever: "down" is all defrost and "up" is front floor and rear vents...oh,
well, I guess one should set up another lever if you still want to choose
between driver feet vents and defrost. 

4) So when the heat is on, all of it comes out at the front foot vents or 
defrost. By operating a lever, one can choose if the heat intake is fresh 
air from underneath the bus or recirculated air from the rear vents. 
Obviously, an inline blower (mounted somewhere up front?) would aid flow...

So, should I do it ????
 
---------------------------------------------------------
Morris Arthur < morris_arthur@unc.edu >
Environmental Sciences and Engineering
University of North Carolina