Air Conditiioning Air Flow Mod

[1L243]

My 13.5 Ducted Dometic Brisk Air 2 Air Conditioner has been a disappointment since the day I bought the trailer (new).

The air would be cold when I used the Dump feature but who wants to listen to that noise. The AC would be on for hours with little improvement. The AC air ducts in the ceiling produce little air flow.

If it was 100 outside I would be lucky to get the trailer down to 90. Hardly even worth it. I thought the system just sucked.

I watched a few youtube videos Where the inside of the AC was modified with foam board to create a more direct flow into the AC Duct vents. I decided to try the MOD and see what happens.

When I pulled everything down from the AC and looked inside the I could see my main problme right away.

When the AC was installed they used a thin foam inside the cavity covering the AC Duct. It looks like they just used a razor knife to cut a slit. Needless to say this does not promote good air flow.

I could have just fixed the Ducts and probably would have mnade a big difference in improving my AC air flow but I decided to go on with the MOD.

I will include the link to the video I used which was a great help. There are other videos for your particular AC unit Plus there is a company that makes a Plug in Foam insert already made. It costs somewhere around $170. The MOD is about $20 in materials.

Youtube
https://www.youtube.com/watch?v=TusVLTNm7_s

AC Duct



Here's what the Duct should look like




You will see in the video that you will use foam board to separate the hot side from the cold side.

You will seal everything up with tin foil tape. You will create a ramps on the top out of foam board that will direct the air better to the AC duct.

On the bottom you will create a defuser or a dog house that will channel the air into the AC duct more directly.




As in the video you will need to tape the electrical box out of the way since it can't go back into it's original position.



You will be creating a air tight box that leaves the air from the AC nowhere else to go except in the AC Duct. The dump feature will no longer work with this mod.


You will have to remove the divider from the metal frame. In the video this seems to be held on my tape. Mine was spot welded in 6 places. I just had to drill them out.

I have to say when completed the airflow is a huge improvement.

I don't know if the video will come out but take my word for it.
https://i.imgur.com/2cbfCDl.mp4

Even if you decide not to do the mod it would be worth it to pull it down to check the openings in your AC ducts.

[StirCrazy]

I like part of this modifacation, I think it only makes sence to make sure the take offs for the vent piping are opened up all the way and the edged are all sealed, but I don't think that triangle blocking plate actualy does much aside from getting rid of your dump feature and any slight leakage you might have while that is closed. nowher in a RV is it designed to have laminer flow throughout the piping and to acheive this you would not only have to do the part you did, but you would have to redesign each register point the same way. other wise what ends up happening is you get a slightly better flow untill all the corners and angles in the tracking allow back pressure to build up. I guess if you don't use your dump it doesnt matter much, but with a bigger 5th wheel if no one is in the bedrooms I open the dump during the day to keep the main body of the 5th cooler. but this has got me thinking maybe I'll pull the cover and see how my take offs are.

[jodeb720]

my neighbors bought a new Travel Trailer - I walked them through the same process - had them seal and do the rest. I used an anemometer (wind Speed) that I have for the house (to balance out my sticks and bricks HVAC) with my 4 x 10 vent adapter.

When In started, the air speed was 8 mph in the bathroom - and less than 5 in the front bedroom. Taping the inside of the baffle, and stopping the short cycling, it increased to 14 in the bathroom and it was 6 in the front bedroom.

After sealing the vents so no air got in the attic (yes, it was leaking there) cutting the pop in insert that was blocking the airflow in the front bedroom and reducing the volume that could come out of the bathroom, front bedroom was at 12, bathroom was at 6 and the other vents were at 10.

A much better experience, and thanks for the pics and instructions. They were so happy!

[C_Schomer]

^^ besides those things I keep my coils clean, wrapped the return plenum with more insulation and replaced the lousy 4” diffusers with 6” step downs. I was sceptical but a reflective roof coating also made a very notable improvement. My ac cools good at Phx now.

[RCMAN46]

I did the modification as described in the video. I measured the air velocity with a Radio Shack wind speed meter. I got about 6 mph before the modification and 8-9 mph after the modification at one of the vents. This is more than 40 percent in line with what is claimed in the video. Well worth the time it took to do the modification.

[ken56]

I already have the materials to do this. I just might try it.

[frankwp]

Thanks for posting this. My AC hardly pushes any air into the front bedroom and this may help with flow.

[Lwiddis]

Thanks for the tutorial. I learned from it.

[Sea_Six]

Holy smokes- I’m wondering if the problem I am having with low air flow after my heat pump was replaced is what you’ve described here.

Thank you soooo much for posting this and with great pictures too. Can’t wait to open up and investigate