Originally Posted by OldCoot
From the picture, it looks like it just fell open and because it does not have a duct flange on it to direct it, it should not be for heating the underbelly. My Flagstaff does not have an open duct in the underbelly, but does have an outlet in the basement. I'd just close it and tape that entire side with the alum furnace tape.
I agree with both of the last post, but and that is big but. If you look at the pileum you have 6 cut outs normally I can see two sides only. There should be I would hope 2 cut outs on the third side which is not shown. A 27' trailer should have more then 2 ducts coming off it. That is why I asked the questions I did. A 4" duct max CFM is like 90 cfm that would only give him 180 CFM total which is not enough to run that furnace. I can only say what I see looking at the picture again you can see the side and front only. There is no ducts at all connected. I have a duct in my basement also. Now you would think that they installed this correctly. This is why I asked those questions even if they took 2 runs off on the other side and split them to a 4x4 wye branch that would even reduce the CFM more. Someone could have just opened that one up to stop the cycling problem off the limit because it can not move enough air. It is my own opinion I designed duct for buildings and homes for 20 years. And 2 4" duct can not deliver the amount of air needed for that furnace. I was just asking a question from my experience. We just had a same issue last week when they had to add a duct per the factory. No one thought that would create more air flow well it did by that op's last post saying they added a duct and now he gets more air flow and now can keep his unit at 70 degrees. This is just my opinion and I wouldn't jump to tape anything up til those questions where answered.......
Plus we all know FR. Those are questions that I would want answers to from FR. Better yet Suburban them selves. These people screw up all the time like my unit without return air in the cabin. Funny after my letter to suburban all 8289ws now come with R/A in the cabin area. And the dealer wasn't happy he had to cut them in my unit per suburbans Gen. Manager.