Blocking the AC ducts

The questions below are specifically based upon my experiences with our 2015 LM Key West but are likely applicable to almost any Heartland product.

I finally got off my butt and started looking at the in-roof ducting for the bedroom air conditioner which services both the bedroom and that bathroom. What I found prompts these questions.

1. The output vent nearest the closet runs about another 18 inches before terminating in the closet. There is no output vent in the closet. Is there any reason I couldn't or shouldn't put some Styrofoam to fill in that 18 inch space so that it forces the cooled air into the bedroom?

2. Looking through the bathroom's output duct toward the kitchen/living room (toward the rear of the trailer), the output duct is almost 90 percent blocked by a piece of wood. This piece of wood has nails protruding from the bottom. This piece of wood effectively blocks any air transfer between the forward AC and the two ACs that service the LR and kitchen.

a. Is this normal? Should this piece of wood be there?

b. Since this duct is almost totally blocked, is there any reason I couldn't or shouldn't place a piece of Styrofoam between the output duct and this piece of wood?

TIA for your comments.

I blocked the bedroom vents just forward of the vent closest to the closet, and just rearward of the bathroom vent.

Did the same for the return side (WhisperQuiet system).

I also did the same for the living room vents, sealing just past the rearward most vents, and forward of the kitchen vents. Although this prevents using the rear air for the bedroom or vice versa, that's fine with us.


Sent from my iPhone using Tapatalk

I basically did what TravelTiger reported. I had noticed when I went to LED lights back in early 2013 that every time I opened up a light fixture I could feel cold air come out. Figured the air duct at the ends were not sealed off.

I used silver heat duct tape. Had to remove it once when the front A/C broke but easy enough to remove and reinstall.

When I blocked my vents, I used closed cell rubber foam, as opposed to styrofoam. The pliable nature of the rubber foam is necessary for inserting the material through the round vent opening.

Before I knew what I was going to do, I bought a 4x8 sheet of rigid insulation. I cut approx 2"x5"pieces off of it to use as my block, then sealed it with metal tape. Fairly easy to remove if needed.


Sent from my iPhone using Tapatalk

When I did the same as Travel Tiger I used hand towels as the temporary fix. Moved them around to find best solution for us. Now I need to do something more permanent today.

Sent from my XT1585 using Tapatalk

I did the same thing with ours but I used pool noodles to block ducts where needed.

I used the grey/black pipe insulation with a 2 1/2 OS diameter cut to 9 1/2" long, after using pool noodle for the first block. Taped up places where the sky light cut out protruded into the duct. This is an area that manufacturing could spend a little more OC on, and I am trying to be PC. I also fourd this hole doing the TSB on the rear AC unit. I would also note that quite a bit of construction debris was found in both AC units. It would be interesting to have a real world user like one of us to be invited to come to the factory and spend a few days with their QC people and be involved in a build. Things like the hole in this first picture should never be let out the door And it do not see the high value insulation on the other side of the opening.



And looking at this photo, I am not sure that the ducts in general are sealed along the bottom the ceiling that well. And you can see a sky light cutout compromising the duct. This is a dead end that is now blocked off.



Chris

We purchased a 2017 3270RS three weeks ago. we had the "water leaking into the bedroom" deal which our dealer addressed. Looking into the duct work my supply air ducting is blocked off between the bathroom and living area just aft of the bathroom and just forward of the living area....which separates the two supply sources. HOWEVER...the return side has no blocks in it so whichever unit is running...that unit will pull return air from the entire coach. shouldn't the return side be seperated as well ?? the supply side ducting is reduced by the shower vent but not totally obstructing. I wonder if all would work better if I pulled the blocks out so both units could work together ?

Relayman said:

We purchased a 2017 3270RS three weeks ago. we had the "water leaking into the bedroom" deal which our dealer addressed. Looking into the duct work my supply air ducting is blocked off between the bathroom and living area just aft of the bathroom and just forward of the living area....which separates the two supply sources. HOWEVER...the return side has no blocks in it so whichever unit is running...that unit will pull return air from the entire coach. shouldn't the return side be seperated as well ?? the supply side ducting is reduced by the shower vent but not totally obstructing. I wonder if all would work better if I pulled the blocks out so both units could work together ?

Click to expand...

Bumping this thread hoping for a response to the boldfaced text about. This is a good question to which many would like a good answer.

Thanks!

TxCowboy said:

Bumping this thread hoping for a response to the boldfaced text about. This is a good question to which many would like a good answer.

Thanks!

Click to expand...

Check this thread, the last post...
https://heartlandowners.org/showthr...uiet-ducting-design-issue?p=498498#post498498


Sent from my iPhone using Tapatalk

Interesting question about the return ducting in a 2015 LM. Upon checking the supply ducting between the 2 a/c units, there is no blockage or partial blockage in the bathroom area. When only one unit is running, we can feel air coming thru all the supply ducts. We have also blocked the ends of the supply ducting (bedroom & main room) by putting a large piece of foam padding (left over from the a mattress topping) behind the vents. Ya can really feel more air coming down thru these end vents, seeming to cool the unit better.

To answer question 1.

According to AC System design there is an over run past the last vent, the length is figured using a formula. The design reason is the AC ductwork operates on pressurizing the system and equally forcing the same amount of air out each vent if non-adjustable. If the duct is blocked just past the last vent the air flow goes to the end and takes the path of least resistance and exits. Therefore the other vents get reduced flow. By extending past the last vent forces the air to reverse and pressurize the system causing equal flow out all vents..

Of course that all depends on a sealed ductwork system to operate properly. Obstructions and improperly sealed ducts, holes, & corners defeat the purpose of the original design and cause a system not performing to design spec. No pressure = no air flow. Well maybe a cool attic.