# ducting problems in 25rss



## aplvlykat (Jan 25, 2004)

I to have a 25rss which has smashed ducts. seeing as how I work in the HVAC industry and that it is a 90 mile round trip to the dealer, I am going to find out why it is smashed. 
There is another problem with this system I noticed rigth off- the return air is restricted. The manu. installed the RA register in the front of the cabnet and when they put the furnace in it all but blocks off the return air, this is a easy fix. Go buy a RA register at the local home depot, measure the side of the cabnet where the fire ext. is, probably around 12x14 to 12x20. Cut out the side leaving enough to screw the new RA register on, problem solved.
I will be dropping the bottom and I will find out why these ducts are smashed. I will get back as to why and how to repair then properly.


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## ctsoderq (Dec 14, 2003)

We just dropped our trailer off at the dealer on Friday to fix our duct, some leaks, and other items (four hour round trip!). I look forward to what you find to see if they fixed ours correctly. I read on another forum that the plastic under the trailer flaps in the wind and hits the duct. Don't know if this is true or not.


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## NDJollyMon (Aug 22, 2003)

aplvlykat...
How is the RA register restricted? What would be the heat effect of this being restricted?


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## aplvlykat (Jan 25, 2004)

Ok this is an update on squashed duct syndrom in the 25rss model. I dropped the bottom today and found out what the problem is. The water tank is installed from frame to frame parallel to the axels. The ducting runs against the floor between the tank and the floor for aprox. 3 feet. This is where the smashed duct is. There is no way this is caused by the bottom flapping in the wind. The first time any water is put into the fresh water tank, like any good ballon it expands and crushes the duct. To compound the problem the stainless steel light weight duct is 2inches high and the frame work that holds the water tank is 11/2 from the floor, it is hard to get a 2 inch duct into a 11/2 space. 
I did not drop the tank instead I installed inside the ducting 2 pieces of 11/2 x 2 x 4 foot light wieght angle iron and screwed through the side and bottom of the duct strenghting the sides of the duct so when water is added it should no longer crush. This should work and stop this problem.
As far as restricted RA, look in your suburban furnace book on page 2. We have the sf30f model. Return air requirements for this unit is 55 sq/in of unobstruted air. This equates to a surface area of 11 x 5 inch register min. If you remove the existing RA reg. and look, if it was done like mine, the only RA you get is from around the edges of the cabnet and the unit. It does not appear to be enough, you can never have enough return air to any forced air system.
Think of it this way, you can only push out the amount of air that the unit can suck in. If the return is restricted it will over heat the heat exchanger and cause failure, it will have a lot of unwanted noise because it is trying to suck through a small opening and the sound is amplified. You will have minimal air flow through out the structures duct system and have cold spots. Air is like water it takes the path of least resistance, this is why it blowes like crazy in the back near the table and very little upfront near the bunks even with the ducting repaired. I may still need to put on a supply regs that can be closed to force more air upfront and balence the air flow throughout the trailor
I hope this helps.


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## ctsoderq (Dec 14, 2003)

Thanks for the great info. The first few times we camped, we didn't use the fresh water tank, as we had hook ups. That explains why the air distribution was fine in our unit for the first couple months, and then the smashed duct problem. I can hear my water tank expand when I fill it - makes sense.

One concern. I may not understand your fix correctly, but it sounds like the angle support would transfer the load of the expanding water tank through the duct to the bottom side of the sub floor. Would the angle try to push the floor up when the water tank expands?

Thanks for the RA suggestion also, I think I'll try it. Our furnace is so loud, it wakes up my wife in the middle of night, when it comes on. Maybe the larger RA will quiet it down.


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## NDJollyMon (Aug 22, 2003)

Thanks for clearing it all up. Sounds like you may have figured out another flaw in the design. I'll be checking out my heat system this Spring when I get the Outback from storage.


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## fixjet (Jan 19, 2004)

aplvlykat,

Is it much of a job to drop the bottom out of the unit to get to the ducting. If the my problem is the same as yours I'll bet the dealer will not modifiy the ducting with reinforcements. Also on mine when running the furnance the flooring will rise up as air is being forced under it. Did yours do that also? Thanks for the input.
Dan


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## ctsoderq (Dec 14, 2003)

Our flooring raised up between the sink cabinets and the sofa slide. The dealer's first fix was to install a closing vent on the rear air register. This made the flooring rise significantly from the rear duct to the center duct. It came up enough such that you could make waves in the flooring by tapping it. It's back at the dealer now, hopefully for a permanent fix.


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## aplvlykat (Jan 25, 2004)

Well it is all done, what a job. To answer some of the question YES it is quite a job to drop the bottom. I will never do it again!! It is no problem getting it down but back up is another thing altogethere. Another factor was the cold when I started in the morning it was 20's and by mid afternoon it was in the 70's but that is desert living here in So. California.
I am hoping that the reinforcing pushing against the floor plus the extra 4 inches of support on the bottom inside the duct will be enough to solve this problem. I will find out in late march when we take it to Big Sur State Beach. As of today I have heat finally to the back and will not have to hear the complaints from the kids.
No, my floor never lifted up, I don't know what this problem could be, other then the duct being crushed and the air going between the floor and the tile? 
If anyone hears from the dealer about this problem I would be interested in how they repaired the ducts? Got to go talk to you all later.


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