Total Pageviews

Thursday, March 24, 2016

Duct Duct WHOOSH!!!

We have a 2004 Winnebago Vectra 40AD Motorhome. This RV has a basement air conditioner. That means that instead of 1, 2 or 3 air conditioners on the roof of the RV, we have 1 huge 2 compressor air conditioner in one of the compartments down below. It is in the compartment at the very rear of the RV on the passenger side. Ours died a year ago or so and was replaced with a brand new unit.

The AC unit is in here on a slide out tray

One thing that is good about the basement air is that it leaves lots of space on the roof for the solar panels. We have 5 panels that are about 2 foot by 4 foot and we have room for a few more, if we ever want them.

The main thing bad about the basement air is that you lose one compartment in the basement that could be additional storage. Another issue is that a LOT of people with basement air have experienced poor cooling when they are in really hot weather in full sun. We have been in the sun on 90 degree days and was only able to get the RV down to the high 80's inside. Think about it. What's your car like when it's sitting in the Walmart parking lot for a couple hours on a sunny hot day? The RV is pretty well insulated and has double pane windows, but it still gets hot fast. On a day like that, it could easily be over 100 degrees in the motorhome. We can open the two roof vents with fans that blow out to get rid of the hot air. That helps a lot, but if we are in a campground with electrical hookups, we run the air conditioning.

I have been researching online to see how others have dealt with the poor cooling of this particular line of RV's and have found that people have solved it mostly by fixing leaks in the duct work. The air conditioner makes the cold air and blows it out into a system of duct work that goes up the rear of the RV behind the rear wall and then splits into a "Y" so it then sends the cold air down 2 lines of 6 vents each for a total of 12 vents mounted in the ceiling of the RV.

This isn't OUR RV but it is a similar model so ours looks like this as far as the ducting is concerned. We don't have a radiator here like this photo shows. Our radiator is on the side of the RV on the drivers side. The area that is leaking is in between the 2 horizontal straps you see near the center of the lower section. This photo is from FIREUP, a very helpful forum poster on His write up is HERE.
There are 12 of these vents on the ceiling. One row of 6 for each of the 2 ducts. The vents have louvers that can be rotated and closed if needed. We close the bedroom ones and close the door during the day to concentrate more air flow to the living area.

Our duct work tape was coming loose in a couple areas. This was allowing a LOT of cold air to escape into the space between the walls. That unsecured duct work is the cold air reaching us inside.

Air was really coming out of here.
My hand is getting COLD!
This area is normally covered by a plate held on with about 10 screws. I had to remove that panel to gain access to the duct. Luckily the area leaking was right there behind this panel otherwise the leak would be really hard to get at.

Herb's is the True Value hardware store in Quartzsite, AZ
This type of aluminum tape was the best thing to use according to the many forum posts I read by others who have done this repair.
The upper right shows the panel that can be removed to gain access to the duct.
Here is the panel after I removed it.
The tape has a backing you must peel off before placing it. After peeling the backing off you have to be careful working with the tape or else you get a sticky tangled mess. 
Had a few of those.
This piece is the typical size of the pieces i was using. Because I was working in a small tight access area I needed to work with these short pieces.
The lower area of the duct had a leak too.
Working my way up the duct one horizontal piece at a time to close the leak in the vertically installed old tape. If the original tape had additional horizontally installed tape this leak probably would not have happened.
Adding another piece. After each piece is placed you rub it smooth. This tape really clings well. The entire area was cleaned with de-greaser first and let dry so
 the new tape would stick better.
As I went up the leak the duct started being more rigid too as the tape was re-enforcing the duct. Like taping a cardboard box for shipping.
Replacing the metal panel (lower left).
The finished project. (Shot from the bottom while lying on the ground facing up) As far as I can see and feel there are no more leaks. There may be leaks way up in the "Y" area of the duct but there's no way to even check that area without removing the entire rear cap of the RV. THAT would be a job for a professional. I'd have THAT done at the Winnebago plant in Iowa if we ever need to.

So the job is done, we start up the generator and the A/C unit and WHOOSH!!! the air coming out of the vents is increased at least 30% form before. Makes sense. Today it got up to 95 degrees F and we got the RV down to 83 inside which, in this dry environment, is very very comfortable. We NEVER got the inside that low on a day as hot as this... NEVER!

I had been toying with the idea of installing one small roof-top A/C unit to augment the main A/C for those occassions that we are having a really hot day. I don't think that will be necessary any more.

I am HAPPY and like Fonzie, we are....... COOL!

1 comment:

Craig MacKenna said...

Our Alfa SeeYa Founder coach also has basement air with 2 compressors. We have one group of outlets near/aft of the front door, more outlets from the front of the kitchen island, one in the bathroom and one in the bedroom, with the inlet near the ceiling in the back of the bedroom.

One early Alfa owner got frustrated by the number of air leaks in the overall coach, so he developed an air-intrusion-prevention procedure that he started doing for other Alfas, which has blossomed into one of the largest and best-known Alfa repair and upgrade centers in the country. We have had that procedure done on our coach.

Some Alfa owners complain of insufficient cooling, and have installed additional roof air conditioning. We have maintained 78 inside with full sun and 105 outside. The trick is to set the A/C early in the morning, so that the units never get behind and have to catch up. Most of the walls of an Alfa are styrofoam insulation, but there are many double-pane windows, so I bet our heat leakage is similar to yours.