[Latitude 28]

Rounded up my fittings for the AH exhaust.  Because the "Y" connector at the vertical stack has a flared tube that the AH exhaust tube slides into there is an union at the AH.  The original had a short tubing welded to the union with the crossover tube flared and clamped over that short tube...that was a major source of the leak.  I wanted to make this joint tight and repairable.   I took a 1 1/4" Rigid electrical conduit coupling and hammered it inside the crossove exhaust tube.  That gave me a solid monolithic pipe thread joint to connect a standard 1 1/4" pipe union to the AH piping.
       

[Jack Houpe]

Out of curiosity how does the generator when running not feed exhaust back through the AH? My shoulder is hurting just looking at those parts Steve, and having to do it on your back too.

[Latitude 28]

Much like a header system with the "Y" joint in play and once the vertical exhaust pipe and generator exhaust system is hot and creating a draft I would think there would be no back flow into the AH system. That would all depend on several variable conditions i.e. which way the wind is blowing, atmosphere conditions and/or weather. I think we did actually have some exhaust fumes from the generator back up into the AH exhaust escaping through the rusted areas of the pipe. For whatever reason we could smell fumes from either unit when run independently of each other. Once I can get the coach out of the garage I will check it out to see if the AH exhaust pipe fixed the situation or not....may have some generator exhaust work to do as well.....talking about a sore neck/back!

[bestgenman]

Jack, my theory is the AQ and generator exhaust are joined where the gasses are vertically oriented and since hot gasses naturally rise, they go up!  The generator would have to force the gasses 180 degrees downward and into the 1-1/4 pipe and then into a 90 degree elbow, across a fairly long horizontal path and up through another 90 degree elbow into the AQ.  The vertical path has much less resistance.   If, and a very long chance if,  there was a pretty stiff wind right into the turn out at the roof level (for those with roof exhaust) , it would be possible to get some engine exhaust back feeding into the AQ.  In all my years on this forum, I have never read about that happening!

Just saying!

[Jack Houpe]

That makes sense and it works so thats all that matters, I'm the weird guy that thinks about that stuff when I'm sleeping. Ha! I haven't had the time to look at the generator it was one of the only things that did work on our coach.

[Richard]

I think both ideas are strong contributors, in addition to that, let’s look at the air flow. We don’t normally think about air as having mass like water or any other fluid flowing but it does. So a fellow named Newton said that an object in motion wants to stay in motion in the same direction unless something changes that direction. Well, that’s close enough to what he said. The air from the generator is flowing merrily along when it encounters the Y junction of the two exhaust pipes. Because it is a Y junction the air flow would have to reverse direction to flow down the AH pipe. Wait, it gets better. Because the Y is actually a crude Venturi setup, the flow of the generator exhaust actually creates a small vacuum on the AH exhaust pipe.
Those factors along with the heat rising phenom mentioned above all work to help the flow upwards and out the the stack.

Now if the gen exhaust were teed into the AH exhaust, that would be a different situation, and you would get gen exhaust trying to go into the AH exhaust.

I don’t know when the design changed, but the 95 I owned had separate vertical pipes. The 99 has the Y combined into one vertical.