My weekend was spent wrestling tubing underneath the bus...

Summary: 
The heat direction box under the floor can't be used as I 
described it in my earlier post because when the small tubes are opened 
via the control cable, they do not block flow from the large tubes. In 
the situation I described, there would still be fresh air entering the 
heat intake along with the interior air. Since the heat system is still 
going to get fresh air from your main cooling fan, I don't think the 
option of choosing fresh air for the auxilary input is all that 
important. I'm going to try ducting the vent from underneath the back 
seat, around in front of the valve covers for 3 and 4, and through the 
engine tin to the aux fan.

John from WV had an interesting suggestion about reversing flow through 
one of the heat exchangers. I'm sort of scared to create a heating 
imbalance on different sides of the engine...

Contact me if you want to know main tube replacement recommendations...

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Morris Arthur < morris_arthur@unc.edu >
Environmental Sciences and Engineering
University of North Carolina