ATF: Bighorn - Whisper Quiet ducting design issue

[TravelTiger]

To cover a few suggestions, the Whisper Quiet setup has no single return air grill at the base of the unit nor does it have any interior access to the chambers of outflow and intake. There is one single opening that blows air at a 90* angle from the single, rig-long duct that runs from front to back of rig. The return air is a second rig-long duct. So essentially your air only comes out one side of the ducts that you see. (We have added some curved metal tape to help make the 90 where the air first enters the duct.

row on left is outflow, row on right in intake.

So "tent-the-vent" won't really work like in previous AC setups, nor is there a way to check if airflow is leaking or misguided from the roof unit.

At 80 degrees outside, both ACs running the inside will hover around 80. If the temp rises, both ACs running can only get me 79*, at best, but typically 11 degrees below exterior. Weather app says its 93, thermometer outside in shade says 84, inside with ACs running full blast since 1, shades all closed, it's 80 inside the living area, and 76 in bedroom, with 4 Vornado fans circulating the air.




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[Gary521]

Something must have changed. I have a 2017 Bighorn and the AC system is completely separate. The front AC cools the bath and bedroom and the back AC the living area. ( Assuming that this is not a factory screw up) I get plenty of air flow out the vents but I probably will need to run both AC's to get the entire unit cooled during really hot days. Maybe we need to get some info from the factory.

 

[Bones]

ok This gets me a little further. When I see your holes I see the bottom of your ceiling and I see hard white foam at the top but I don't see a duct in there. Can you stick your hands up there and see where the sides of the duct stop? can you see all the way through to the other side? Is there a possibility that the duct is missing and your air is just getting dumped into the ceiling?

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Another step would involve getting on the roof and removing the AC covers and looking inside to see how things are routed and to see if there are any type of blockages. Your condition is leading me to believe something is not flowing correctly and not returning back to the ac units. You already know that the air conditioners need to compound cool to get to your desired temp with a 20 degree differential.

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Shine a flashlight up in the duct and take pictures. Another thought would be to try and look into the duct from the camper around the same location the air conditioner is suppose to be.

 

[GETnBYE]

ok This gets me a little further. When I see your holes I see the bottom of your ceiling and I see hard white foam at the top but I don't see a duct in there. Can you stick your hands up there and see where the sides of the duct stop? can you see all the way through to the other side? Is there a possibility that the duct is missing and your air is just getting dumped into the ceiling?

- - - Updated - - -

Another step would involve getting on the roof and removing the AC covers and looking inside to see how things are routed and to see if there are any type of blockages. Your condition is leading me to believe something is not flowing correctly and not returning back to the ac units. You already know that the air conditioners need to compound cool to get to your desired temp with a 20 degree differential.

- - - Updated - - -

Shine a flashlight up in the duct and take pictures. Another thought would be to try and look into the duct from the camper around the same location the air conditioner is suppose to be.

Here is mine.

 

[Toy1Ton]

the hard white foam is the duct work

 

[avvidclif]

Be interesting to see if the outside of the duct is sealed with tape where it meets the ceiling. If not that's a lot of air lost in the gap between the ceiling and duct. It's not large but LONG.

 

[TravelTiger]

I don't have one from the living room because the ladder is back in the basement, but here's one from the bedroom vent looking towards the rear of the coach. Yes there's a black and grey tank vent going through it, and possibly some wiring. But that's not near the area of issue.

The duct is formed out of the styrofoam, so no seams except where the ceiling board contacts it.


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[avvidclif]

How about that big gap around the pipe????

 

[TravelTiger]

How about that big gap around the pipe????

Clif,

I'm not really worried about this pic. I don't think it's a big gap.

The bedroom AC cools great. The bathroom vent almost has too much volume. The living AC is where my issues are, and that part of the duct in the pic (with the pipes) is far away from my issues, so likely a non-factor.




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[Bones]

Well, I definitely don't like the design but you have to work with what you got. . I do think your next step is to go through the duct work and look where your air conditioner meets the duct work. If that is in the back you'l need a ladder. I do think you are loosing air in the gap between the ceiling board and the half A#$ duct and I have no way of telling. One thing you can do is measure air flow. You would need an air meter of some sort. You would measure at the source then measure along the duct to see where your loss is happening. Since you said your front AC provides good air tells me that even though the duct work is not ideal it works so it leads me to think that there is some type of connection failure in your rear AC. You may need to go up on the roof and remove the shroud and see if you are getting any blow back from a clogged duct.

On a side note I really don't think a dealership would go though this much trouble to figure out what is wrong with your AC.

 

[farside291]

Maybe the air is traveling too fast through the ducts. The current design of the vents with the lip in the air path, the air is just passing over the vent. If there was a vent that had louvers that protruded into the duct to catch the air as it passed. That would probably make a huge difference. When I get back to the trailer I am going to take the lipped portion out and mount only the spaceport vent in the hole with the louvers facing airflow. This will put the louvers directly in the air flow.

 

[GETnBYE]

Maybe the air is traveling too fast through the ducts. The current design of the vents with the lip in the air path, the air is just passing over the vent. If there was a vent that had louvers that protruded into the duct to catch the air as it passed. That would probably make a huge difference. When I get back to the trailer I am going to take the lipped portion out and mount only the spaceport vent in the hole with the louvers facing airflow. This will put the louvers directly in the air flow.

yes, the air is passing the vents without being sent down the 90 degree turn with nothing to help direct that turn.
the vent louvers are to short to reach high enough to change the air flow direction.
from what I feel without using any tools, is that the air is stronger at the top level of the duct. What we need is something to block and direct downward some of the air at a vent, at the same time not blocking it all to allow some air flow to travel on to the other vents (bedroom) area. I am now looking to a piece of foam that I can shape in a crescent shape to go on the side of the round vent to send some of the air down. But, at the same time not block the entire vent.

 

[GETnBYE]

I am also thinking of trying to find a piece to fit on the vent that will "catch" the air and send it downward toward the louvers. Something similar to the pic below. It would have to be altered in some way because there is very little room to work with and if the top portion could be rectangle to match the duct it would work better. Perhaps just a piece of flexible vent like dryer vent could work. At this point it's try anything time.
what do you all think??

 

[farside291]

That would definitely work for 1 vent but block everything else. The spaceport vent louvers are much larger and I believe will catch more air. They should protrude into the vent about a 1/2 inch or so without the lipped spacer installed. Question is I am not sure if the diameter will be large enough to cover the hole. I won't be back at the trailer for a few weeks to try it out.

 

[Westwind]

Something to think about - someone mentioned that they thought the air was being pushed beyond the vent opening - at night when in bed I notice that when our AC drops automatically from high fan to low fan I get the feeling that more cold air is being blown over me. The part that doesn't figure in is more air should be headed to the end vents and it doesn't sound like that is happening.

 

[TravelTiger]

Something to think about - someone mentioned that they thought the air was being pushed beyond the vent opening - at night when in bed I notice that when our AC drops automatically from high fan to low fan I get the feeling that more cold air is being blown over me. The part that doesn't figure in is more air should be headed to the end vents and it doesn't sound like that is happening.

Yes, blocking just past the last vent in the line does help.

 

[kenwessels1451]

I bought a pool noodle at the dollar store and cut 4 pcs at 11 in. They fit perfectly in the duct to block the air. I have them at each end of the living room ducts. That saves a 6 ft run to a dead end and a 3 or 4 ft run to the other end. I have only 3 registers in rhe 3570rs and with the back pressure the center blows as hard as the ends. A lot more cool air blows now. I did the same to the 2 ducts in the bedroom. We're waiting for a day the temp gets into the 90's to see what the variance btwn inside and outside. It has been around a 10 degrees. I know it will be better but 20 degrees probably not.
As a work around in the past have the bedroom set low and on high fan and have Dyson AM-09 at the doorway blowing into the living room. When it was 100 degrees it made about 83 down stairs. I expect better now that the end runs are blocked. We'll see.

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[mikeandconnie]

We had terrible flow and it was very hot in our rig when we first got it. However as I write this in Tampa Fla 92 degree outside in direct sun, My DW is freezing me with the ac control, it's 68 degree inside and I feel the air from the vent sitting in my chair. I did the following and very happy with the results.

Removed the AC units and Tapped up many openings in the collector boxes. Help some!
Closed off the duct at the end of the first and last vent. Help a lot!
Closed off part of the vent in the bathroom by taping the back of the vent with clear medical tap. We had too much air in the bathroom making it very cold.
Closed off the duct between the front and back AC. This help a lot in the bedroom.
I cut a few louvers out in the vents in the bedroom and I can feel cold flow airflow laying in bed. I have two vents and may add another one but really don't think I need it.
Mike

 

[farside291]

Thinking back, when we were younger we had a 75 foot mobile home with in floor registers. It also had one long running duct from the front of the trailer to the back. But, the duct was very large closest to the AC blower and very small at the furthest end. The airflow would increase In velocity because of the tapering vent the further it got from the AC blower. Now I know that this doesn't help us with our poor air flow but just thinking.

 

[TravelTiger]

Using my very thick business cards, I tried these as diverters using the OEM vents. They help some, but not significantly. It depends of course on the flow of air and the direction you face them.