DL3 ductwork

[Jim Blackwood]

Hey guys. I've been looking at the ductwork in my '96 and most of it is straightforward enough, with the exception of finding return ductwork buried in part of the bottom of a section of the big stainless distribution ducts (that was a little weird but well, ok.) What is NOT straightforward and what I hope someone can help with is that area behind the side panels under the windows. I've not so far been able to figure that out at all.

First off, (and I'd start the bus and check for airflow myself but I'm still waiting on batteries) does air flow out from the gap at the bottom of the windows? That would seem to make the most sense but if it does, where does it come from? I've not found any connection between that and the distribution ducts. I'll take another look tomorrow but so far I haven't seen and transfer slots or anything. Anyone know exactly where they would be? Can't really see any practical way that they could be returns.

I guess that's it really. I think I have the rest of it figured out. Just this one puzzle at least for now.

Jim

[buswarrior]

Buses have used a "warm wall" style air distribution for many decades.

The air is distributed in the duct at the wall/floor corner, the "wall" is a false front on a cavity, which bleeds air to the base of the windows.

A most pleasant way to keep the window seat passenger from freezing in winter.

And when AC came along, well, thru the same spaces it goes.

The half and half return air in the rear is an elegant way to get the return air past the drive wheel cavity. The rear of the coach gets cold, if that set of ducts has been fooled with and not put back right. No return air, there's no circulation...

The space for the air to bleed thru to the windows is small, as the size is what pushes the rest of the air to the back of the coachgap too big, the air takes the easy route out...

Happy coaching!
Buswarrior

[hogi6123]

The bus walls have about 1/2" space behind them, and yes, the heated air comes out there.

If i remember correctly, there are stainless squarish sections at the base of each wall that run the length of the bus that basically are the heat ducts.

At the center of the bus, in the battery compartment, is an angled fiberglass formed piece that connects the blower area down below into the side ducts.

[Jim Blackwood]

Did a little more thorough checking, and yes, the seat rail extrusions have a spacer to the inner wall that allows air through. If a section of duct is removed you can stick a stir stick up in there quite a ways. So that is how the air gets to the warm wall.

The rear air return ducts are interesting. They take up the lower half of the supply duct and are vented to the rear. The driver's side only, has vent slots directly below a set of distribution vent slots under the 3rd window from the rear which is now my toilet area. Not sure exactly how they interfaced with the lavatory since mine was gone and the ducts had been cut off below the 2nd window from the rear but I will have to reconstruct something there for the bedroom. The good news? The toilet area already has it's own set of supply and return slots. I also cut the doors 1" shy of the floor for air return. Thinking ahead but it doesn't hurt to get lucky either. My bedroom ductwork may end up making use of the wardrobe bases. That could be a good use of space. The rest of the bus is served by the front air returns in the sides of the slanted isle and by the stairs.

I think this will work out fine. I loaded in the fridge and the washing machine and with the ductwork in place they don't intrude unduly into the isle space. Should be fine.

I also have a plan in effect to duct the bin AC units through the bulkheads and into the bath and bedroom, partially completed. That could end up being routed through the upper wardrobe cabinets.

Jim