Amazing A/C airflow Improvement

[lesleyinky]

So I've been asking questions lately about adding a 2nd a/c to our new 2016 31sqb. The single 15,000 btu has just not been cutting the heat of our Ky summer.
Before taking the plunge to add another unit, last night we pulled off all vent covers and the main A/C panel and began to clean up and better tape off duct work openings. To back up a bit, the air flow has never (3 weekend trips so far), felt very optimal. The master bdrm and bunk room just felt weak. So anyway, when we start really examining the bunk room vent we were stunned to realize that the duct for that vent continued more than 4 feet past the vent to the back of the TT with no more vents. Just flowed back there to nothing? Then, we checked our master bdrm and same story.....about 3 feet of dead space it went to past the vent with no where really to go.
After a trip for supplies, my husband blocked off the back sides only of each vent with some thick styrofoam type product and neatly foil taped it all off. Now, those two vents essentially have a dead end at the vent rather than several feet beyond them. As soon as we got it all out back together and turned it on we were amazed! Saw dust was coming out in both rooms and going everywhere. Apparently the air flow was so weak before, it never even stirred up that dust that was there from construction until we did this!
All this being said, the true test will be our next hot weekend trip. We may still end up needing another unit but this is bound to help!!

http://uploads.tapatalk-cdn.com/20160719/e8583baf236582d73695505d6be8a142.jpg

This bunk room picture shows how far the dead space is from the vent to the back of the trailer where the duct stopped.


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[Alpine]

Excellent work...ya gotta love a bit of DIY!!!

[ctbruce]

Awesome. I m going to check this scenario out in my Impact 312. Bedroom flow is nil, dame in the garage. Would be totally worth the investment in a little time and tape!

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[therink]

I did the exact same Mod on my duct work on my current and last rig. That is the way the AC ducts are built on all units I have seen. They basically run a ceiling duct (one size fits all) the entire length of the ceiling and the vent openings are placed where ever they need to be based on the model. Not exactly efficient. I experienced at least a 30 percent flow improvemen. My 15k AC cools my 37 foot fifth wheel with no problem.

[ctbruce]

Quick question:. How did you get the vents out? Do the just pull down? I have been accused of having bull-in-the-china-shop syndrome, so it's better for me to ask first! TIA!

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[lesleyinky]

Quick question:. How did you get the vents out? Do the just pull down? I have been accused of having bull-in-the-china-shop syndrome, so it's better for me to ask first! TIA!

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Ha - yes, you'd hate break one! They do just unsnap from the outside. If you look closely there should 3-4 places they clip on and we just slowly pried each one off by unsnapping all the way around.


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[byrdr1]

did this same thing on mine in the early spring.. before the summer beach trip.
I had one fo those nice foil rolls of tape and I used right much fixing these vents and on the main unit areas. Lots of holes and gaps. they are very easy to pop off and put back on.
randy

[concours]

Thanks for the tip I looked at ours today and found the same condition, fixed now with a piece of cellulose foam and duct tape

[therink]

Another thing I did was remove the inside cover on the AC and cleaned up and retaped (foil tape) the interior plenum areas. The factory tape job was pretty sloppy in there. This ensured the outbound duct openings were smooth with no restrictions and ensured the panel between the supply and return sides was well sealed to prevent air leaks.
A small flat head screw driver works well to remove the ceiling vent covers. They take a little coaxing but do pop off easily.

[instymp]

I am old & dense! So you have enough room to work in through the little hole when you pop the vent covers off?

[lesleyinky]

It was just enough space to stick some insulation and tape it into place. This is the type he used.....
http://uploads.tapatalk-cdn.com/20160720/b162f6dec9cc77a43792411ae9b4f7ff.jpg
My husband stuck his cell phone camera up there and took a picture to see how far the duct went back.
This picture shows the shot facing the main A/C and the section of the duct that needed to be open....
http://uploads.tapatalk-cdn.com/20160720/7f736c88b798b01d18c72af233ab4702.jpg

And this is the side he blocked off....
http://uploads.tapatalk-cdn.com/20160720/7a7505fc741da8b6cdb2fdd1f5ae395d.jpg

Hope that makes sense and explains it better!


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[336]

Great tip. I just checked this in my 336 bhs cougar. Same thing. Not as drastic in the master, prob about 1' overrun. In the bunk house at least 4'. Used some of the thick Hvac aluminum tape to block off the ends and funnel it out the vents. Came out great. And while I was looking around in the bath vent I found the duct cutout for the vent just shoved up in the duct. Lazy. And stupid. That had to be reducing flow as well. Thanks again for the tip

[Lee]

Great thread.

So when the duct continues past the vent to the end of the ceiling space,... is the duct end open or sealed shut? Would hate to think A/C is blowing cold air into the ceiling space.

[lesleyinky]

Great thread.



So when the duct continues past the vent to the end of the ceiling space,... is the duct end open or sealed shut? Would hate to think A/C is blowing cold air into the ceiling space.



I am assuming shut.....lets hope!
The camera photo really couldn't capture all the way to where it stopped because it was so dark.


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[therink]

I am sure it should be pinchedshut on the ends but who knows. The best thing to do is place a small mirror at angle up into the vent and shine a flashlight on the mirror and you will get a good view of the duct runs. Works good in heat/floor runs too.

[nellie1289]

Does anyone have a link to the foam they maybe used ? Amazon or Home Depot ?

[slow]

I cut a swim noodle into a square cross section using an exacto knife and used it to close my ducts off with a snug fit.

Easiest and quickest mod yet. Thanks for posting about the extensions. Did not know about it.


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[lesleyinky]

Does anyone have a link to the foam they maybe used ? Amazon or Home Depot ?



This is what we used but I love the swim noodle idea someone else mentioned!
http://m.lowes.com/pd/Dow-STYROFOAM-14-6-sq-ft-Unfaced-Polystyrene-Roll-Insulation-3-5-in-W-x-50-ft-L/50071519


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[Dave W]

I haven't done this 5er yet but did the last one with ho-hum results. I guess CRS occurred as I had completely forgotten this mod on the current 5er though not sure that the rear mounted original a/c has enough 'strength' to push cooled air 30 plus feet for a nicely chilled bedroom in this one. Adding a second a/c I found works well as it isn't ducted and feeds only the bedroom.

I'll do ours next week when we go back to the CG. I have some 2" foam insulation sheeting as well some big foam shipping blocks from a purchase that I can use with aluminum tape.

A note - I found that pulling the entire grill assembly off by removing the 3-4 screws gives you a bit more hand room

[fla-gypsy]

Now I've got to check mine, great idea

[concours]

Just a quick update I used a piece of 1" pipe insulation the type that is split to wrap water pipes it fits perfectly I also slid some aluminum foil insulation into the void as there is no insulation in that empty area which is 30" by 8" every little helps with the heating and cooling

[Richard Noble]

What a great hint! I just checked mine out and same problem. I used a Harbor Freight 3' video inspection camera and found the bedroom duck goes way past 3' and that each vent is losing cold air into the ceiling due to terrible taping job. I'll rectify this problem tomorrow. Thanks!

[Dave W]

I did ours this morning using that piece of sheet insulation noted above and some aluminum foil tape to seal it completely. There seems to be somewhat better cooled air flow --- or at least I want there to be more:). I also have blocked one side of the louvers on the vent in the bathroom which is only about 3-4 feet away from the one in the bedroom. One of the ducts had 18 inches of deadheaded area and the other 6-8 inches.

[rbev2308]

Well after a year of fighting my AC in my Alpine, I have finally gotten some resolution. I have had a heck of a time keeping the unit under 77 degrees even when starting it off pegging the thermostat at 68 first thing in the morning. The unit would stay at 68 and by 10AM be at 72 and by 1PM be at 74 and then settle between 76-79 after 5PM all depending on outside air temps. Mainly due to two large opposing slides mainly with windows in the Alpine 3535RE. So I ran a test for air flow rate and then compared to a replacement vent I placed in one and detected a large improvement in air flow. So I spent $70 and replaced all 7 in the camper. The older installed vents have only a hair under 2" of avail airflow in the nearly 4.5 in width. The newer vents which can be closed completely, have nearly 3.75" of air flow. Ordered off Amazon but are avail several places. Just be mindful of your collar size which mine was 1.5 inches. Anyway, turned AC on this morning and it was 81 inside at 845AM. Outside temp was 83. At 4PM this afternoon, outside temp is 89 with heat index of 97 and camper is in full sun. Inside temp is 69 in living room and 68 in bedroom. The camper has never seen any temp below 74 this late in the day since I bought it...Why does Keystone find the need to restrict airflow so much. Even my HVAC buddy came by and read to make sure I was not allowing too much airflow to cause a problem back in the return to the unit..

https://www.amazon.com/gp/product/B0095TEF4Y/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

[Dave W]

Well after a year of fighting my AC in my Alpine, I have finally gotten some resolution.....................

I had a couple of their damper version only on our Titanium and now just ordered six deluxe from here:https://www.rvupgradestore.com/

Thanks for the reminder that these 'gadgets' work well

[papi]

Thanks for the idea. I actually did it on mine and there is a big difference. I found two of the vents with no tape at all :eek: but I got it all fixed. :)

[Richard Noble]

Finished this mod Sat. temp was 102 and the A/C ran the inside temp down to 77. I've never had that good a drop off before. Thanks again for this hint!

[lesleyinky]

I am so glad so many people have found this helpful! We finally had a chance to take ours out last weekend since the mod and we were very please with the difference it made! The bunkroom in particular, had never cooled so well before.


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[JimQ]

I checked the vents in our Bullet and found the duct in the end vent in the rear kitchen continued past the opening. I used a piece if soft pipe insulation(3/4") about 8" long, curled it and placed it in, nice snug fit. No need to cool the void beyond! The vent in the bedroom was fine. That duct ended at the vent opening. Thank you for sharing with everyone this great tip. Jim

[Dr Bobs Patient]

I'm a new owner of a Cougar 333MKS 5er and found that the AC was having difficulty in keeping up in 95° heat. I found this thread and decided to check out the AC ducts. Not only did the ducts extend well beyond the last vent, I found that the outlets from the rooftop unit only had about 1/2 of the outlet open. When the AC was installed, the 1-5/8" x 8" openings were taped over when the installer sealed the unit then poked a hole through the tape with only three fingers. After opening these outlets and sealing off the extra ducts, the airflow was great. So thank you OP for starting this thread and everyone who has chimed in. Next mod will be replacing the vents with something that can adjust the flow or even close it off.

Peace
Bruce

[Dave W]

................ Next mod will be replacing the vents with something that can adjust the flow or even close it off.

Peace
Bruce

Bruce, after replacing the vent, I have found that it is the possible best thing done to improve the flow. Just be careful mating the louvers with the base if using the JR pieces. I was able with little effort to break a pivot on the last one. Oh and on ours, 95 degrees and was able to take the temp to the thermostat set point of 76

[txbowhunter]

Mark for later


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[zenbuck]

Filled the void on mine as well.. Back vent was far worse then the front... Great tip to improve the air flow!

[Blrmaker]

With an all black camper, AC has been tough to keep regulated. Thanks for this thread. We will be looking at the ac flow as soon as i get home.

[Jhanemann]

We just checked ours and found lots of wasted air space. http://uploads.tapatalk-cdn.com/20160910/6c35eb6953c590301d650efa2f9fce30.jpg this is the master bedroom in the back of the camper
http://uploads.tapatalk-cdn.com/20160910/649210b5302eaaecb75106e21c23cd94.jpg
This is the bunkhouse in the front. We are considering using spray foam insulation. Has anyone considered this? Looking for opinions, pros and cons.
Thanks!

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[Jhanemann]

BTW we have a 2014 Keystone Sprinter 320bhs

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[bitten]

I will have to try this on my Montana


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[Bolo4u]

We just checked ours and found lots of wasted air space. http://uploads.tapatalk-cdn.com/20160910/6c35eb6953c590301d650efa2f9fce30.jpg this is the master bedroom in the back of the camper
http://uploads.tapatalk-cdn.com/20160910/649210b5302eaaecb75106e21c23cd94.jpg
This is the bunkhouse in the front. We are considering using spray foam insulation. Has anyone considered this? Looking for opinions, pros and cons.
Thanks!

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The AC duct tunnel at the front of our Cougar 333mks, extends about 2 feet beyond where the lone vent is located. I blocked off the vent in the bathroom, and cut a piece of pipe insulation a couple of inches longer than the tunnel is wide. I stuffed it in the tunnel where the bedroom vent is and shaped it like a U, curving around the vent. Now the air dumps out at the vent with greater volume/force than before. I also purchased a tall rotating fan at Costco and it came with a small (about 12 inch tall) fan (multi speed, rotate on or off) which we use in the bedroom, sitting on the dresser, to circulate the air.


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[Johnny's Journey]

Hmm?, my AC isn't ducted but the floor furnace is. Seem's I wasn't imagining things when I thought it's ducting continued to no where. Thanks for the cool hot tip off. :cool:

[concours]

I did the same update about a year ago but instead of just blocking off the excess dead space in the duct work I cut 4"strips of foil insulation and slid them along the dead space i think that you can stack the strips about 4 high, which helps with the insulation factor. As for checking the foil tape in the air conditioning unit its worth taking the time to do this as the original install is usually a poor job. If you go online and look at the install instructions for your unit it shows exactly where the tape should be. I suggest that you disconnect the shore power while working in the AC unit

[dwall]

Thanks so much for this thread. I have always had to set up a fan to push air from the rear of my tt to the bedroom. I just went to check and spent about 30 minutes blocking the excess duct and applying more tape to seal off leaks and I increased the airflow nearly 50%. Wow what a difference! It actually blew my hair (what little I have) while sitting on my bed. Next trip I may take along supplies and make a little extra money while in the campground. Low airflow has always been a discussion around the campfire with other guests.


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[keyholeelf]

We used a pool noodle. Cut it so it was tight and shoved it in there. It vastly improved the amount of air we were getting.
https://drive.google.com/open?id=0B2M1Kd5BjojyRmVlbnRxOVllV3c
https://drive.google.com/open?id=0B2M1Kd5BjojydTZzX0hEcHJlM1U

[BlackNoir]

Donald, I hate to tell you this but those pool noodles dry up and turn brittle. It won't be immediate but in a year or 2 you might start getting odd green things floating in the air. Next time you're at a box store i'd grab something like pipe insulation, thats what i'm going to go with myself, it should hold up much better.

[slow]

Donald, I hate to tell you this but those pool noodles dry up and turn brittle. It won't be immediate but in a year or 2 you might start getting odd green things floating in the air. Next time you're at a box store i'd grab something like pipe insulation, thats what i'm going to go with myself, it should hold up much better.



True if exposed to UV (sunlight).

I have a few in the garage I use for projects. Been there longer than I can remember without degradation.


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[BlackNoir]

Cool, i wasn't 100% if it was UV related.

[Seven Gable]

I used window air conditioner foam weatherstriping (for filling inbetween the upper & lower wimdows). I cut it a few inches longer than the duct and curved it into a U shape and tapered the cuts at the ends. Worked very well.

Here is a link: https://www.lowes.com/pd/Frost-King-3-5-ft-Grey-PVC-Foam-Air-Conditioner-Weatherstrip/3062423

[Kenporacer]

Wow, what a difference his hack made. Just finished and can tell a difference of flow in each vent. I had already taped inside the unit. Thanks! Never thought of checking to see how far the ductwork goes!

[CaptnJohn]

Thanks so much for this thread. I have always had to set up a fan to push air from the rear of my tt to the bedroom. I just went to check and spent about 30 minutes blocking the excess duct and applying more tape to seal off leaks and I increased the airflow nearly 50%. Wow what a difference! It actually blew my hair (what little I have) while sitting on my bed. Next trip I may take along supplies and make a little extra money while in the campground. Low airflow has always been a discussion around the campfire with other guests.


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Good idea! I'll be at I-95 Exit 1 a couple days in Sept,,, :D

[jsmith948]

Re-checked the tape on our vents and found it to have come loose from the duct on 3 of the 4 vents. Looks like the tape had been applied right over the construction debris/dust. Removed all the old tape and applied new. I had previously taped up the exhaust and return plenum but thought I would re-check. The forward 'wall' of the return is formed by a piece of luan poorly fitted between the frame work on which the a/c is mounted. There was about a 1/2" gap on one side and the factory crew had drilled 1" holes for the wires. All this allowed hot air from the 'attic' to be drawn into the a/c. Don't know how I missed it before:hide:. While I had the cover down, I vacuumed the dirt from the coil (we live in a dust bowl). Huge difference now in the volume and temperature of the a/c exhaust.

[rrjernigan]

I checked my Montana but couldn't tell if I needed to block any of the vents. The two units seem to be at either end of the camper so I was afraid of blocking the flow coming from the a/c unit to the vent. I am replacing all the vents. The air flow with the vents that came with the unit isn't all that strong. When I took off the covers it seemed much stronger. I need a vent cover that allows for max flow but gives me the ability to direct it. I'm also thinking of adding that third a/c unit. Anyone had any experience with that? We considered it when we purchased the unit but the salesman didn't seem to think it was needed or all that worthwhile. We just spent two weeks in Austin, in full sun with 100-106 temps. It was obviously hot. I have to be in Texas for summers the next few years and if the third unit helps it might be worth the $1,300 to install.

[John&Genny]

There is a lot of great suggestions here for increasing the AC airflow and I'm doing some of them now, such as checking the duct openings, replacing some of the vent covers that would allow more airflow, etc. However I wanted to share with you a picture of the AC controller stuffed inside the return air vent of the 13.5K BTU bedroom AC.

And I mean the controller is literally stuffed inside the return air vent. The one in the 15K BTU is mounted on one of the upper side panels of the return air vent like it should be, but not this one. And they wonder why people complain that their AC system is not efficient. It's obvious that some worker at Keystone just got lazy or didn't care about their workmanship.

One thing I had to laugh at when looking inside both units was the squirrel cage blower wheel they used in the 13.5K vs. 15K units. One is obviously smaller than the other. I'm betting that if you replaced the 13.5K blower wheel with the same size that's in the 15K AC, you could magically convert it to a 15K BTU unit :)

[Skippy38]

My airflow was pretty good but I wanted a little more in the bedroom of my 29RLI so I took the vent off and removed every other vent fin with a Dremel tool. Now it literally PUMPS cold air to the front of the unit.

[xrated]

So, someone please post up with info on what aftermarket vent covers you like best.....brand, model of cover, etc. I need a couple that are adjustable for both direction and to be able to close off completely.....5" duct opening and preferably....black. White will suffice if no black ones are available.

[Canonman]

So, someone please post up with info on what aftermarket vent covers you like best.....brand, model of cover, etc. I need a couple that are adjustable for both direction and to be able to close off completely.....5" duct opening and preferably....black. White will suffice if no black ones are available.
Here's the on we used. I think the post on this thread was 24:
http://www.americanrvcompany.com/JR-Products-ACG25DPW-A-CoolVent-Deluxe-Adjustable-Ceiling-Vent-0.25-Collar-Depth?gclid=EAIaIQobChMInemJvq_I1QIVSZR-Ch2k1AVTEAQYBCABEgKa8PD_BwE

[Ddubya]

I too have replaced all of the vents and sealed the duct around them. Great improvement as expected but don't forget the return air vents. I found that one of mine was sucking air from the ceiling cavity and another had a very long run to the end. After correcting I had much better flow in the return system.

[ken56]

Just checked mine and had the same condition. I blocked off the ends of the duct runs and taped up gaps a best as I could. I can't check air flow as yet but I am confident that it is much improved. In the process of sealing up the supply box now.

[Wayne883]

Excellent information shared. I'll be checking mine soon. This makes me wonder though, why are these trailers so expensive to buy with this type of craftsmanship/labor because in my mind, it takes less time to not cut it to the correct length, but then it hit me. It must be all of the extra material they're using. LOL Thanks for the posts.

[muddynoll]

I just did all of our vents a few weeks ago. We have an Impact 312 that was just built in February. The garage vents were blowing cold air into the roof area. I blocked off the end runs with 1 inch high density foam, and re taped all of the vent exits. I also replaced the vents in the garage with vents that could be shut off since there is an A/C unit in the garage. The duct at the A/c unit was also partially blocked as well. I opened it up and re taped. Now we have much better air flow. Sad how little attention to detail is taken when they build these things.

[msubobcats]

After all these posts I thought I would check outs.
"The cooling chamber", just reaching up and checking the surface of the chamber, is warm. The ducting going forward and back is maybe 1 1/2x8 and leaving the chamber the was probably a 1/2" gap at the top of the ducting. .. Going into the ceiling/roof cavity... So I taped those areas. And reaching into the bedroom duct it is also fairly warm.
So we will see how it goes as we are heading to Vacaville next Saturday for four days.
FYI Matchbook Winery is having a tasting and the Cousins Maine Lobster Food truck will be there!!!!!

[John&Genny]

Here's the on we used. I think the post on this thread was 24:
http://www.americanrvcompany.com/JR-Products-ACG25DPW-A-CoolVent-Deluxe-Adjustable-Ceiling-Vent-0.25-Collar-Depth?gclid=EAIaIQobChMInemJvq_I1QIVSZR-Ch2k1AVTEAQYBCABEgKa8PD_BwE

Just be aware that there are two basic models of this vent, one with a .25 inch collar as shown in the link, the other with a 1-1/2 inch collar which is what I needed for my RV. Be sure to take one of the old ones out to make sure you will get the proper replacement.

[bill-e]

Is the ductwork the same stuff as used in the heat ducts or something else?

[JRTJH]

No it is a different material. Heat ducts are typically "very thin aluminum" in a square/rectangular shape attached to aluminized "coil spring" ducting (similar to dryer vent). The air conditioning ductwork is 3/8" or 1/2" rigid foam (insulated to keep in the cool air) and usually lined/covered with aluminum foil.

[15hideout27rbwe]

Just did this mod today with low expansion spray foam. Haven't tried it yet, but it's obvious that it will make a difference. Awesome mod!

[bitten]

2017 Montana 3720RL.

RV has the hidden a/c units. The return duct is 1 1/2 inch at the vent but closes to about 3/4 as it goes to the center of the roof and the a/c. How far up the ducting should I enlarge the hole?

THe supply vent covers really cut down on airflow. I run the air when the RV is plugged into the house, but just the front unit over the kitchen/living room. The two a/c units share common supply vents and if I remove a vent cover in the bedroom I get some serious airflow from the a/c at the other end of the RV. Anyone bought new vent covers for this model? Btw, all of my supply vents were properly taped at the factory. Current covers appear to extend 1/4 to 3/8 into the supply ducting.


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[thetanman1957]

Just did this mod today with low expansion spray foam. Haven't tried it yet, but it's obvious that it will make a difference. Awesome mod!

How did the spray foam work? What is the approximate dimensions of the ductwork?

[15hideout27rbwe]

How did the spray foam work? What is the approximate dimensions of the ductwork?

Haven't tried it yet. Of course I did the mod right at the end of the hot season. The foam seems to have filled the opening pretty good. If I remember I measured about 1.25" from the top of the ducting to the bottom, and is probaby about 2" past either side of the vent opening. I'd say about 8" wide overall by 1.25" tall give or take.

[lesleyinky]

I'm so glad more than a year later this tip is still coming in handy! When I originally posted I had no idea so many people would be interested.

A little update for us, while it did help significantly, we finally decided we needed a second a/c regardless. We decided we spent too much money buying our TT to not be 100% satisfied.

I will note that we saved some money by purchasing the new a/c off of amazon and then having CW to do the install. They charged $125 to install the one we bought, and we agreed $125 was worth my husband not having to fool with it!


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[IRV2]

Silly question before I rip off the little round vent cover, how do you tape it? are you able to get some of the ducting out through the vent hole after taking off the vent and tape around the outside of it? or are you placing tape on the inside of the ducting? :whistling: I'm not close to my unit so thats why I ask. Also thanks for starting a thread like this maybe it should be a sticky:)

[John&Genny]

Silly question before I rip off the little round vent cover, how do you tape it? are you able to get some of the ducting out through the vent hole after taking off the vent and tape around the outside of it? or are you placing tape on the inside of the ducting? :whistling: I'm not close to my unit so thats why I ask. Also thanks for starting a thread like this maybe it should be a sticky:)

The inside. When you remove the vent screws and pull off the vent itself, you will see that often they don't do a very good job of taping to prevent air from getting into the ceiling. That's what you are doing, plugging up some of the holes. If you have a vent cover that has a 1-1/2" collar, that will help as it will prevent some of the air from escaping. I just bought a bunch of new vents that had a higher airflow, did the taping with the aluminum tape, and we will see what happens next summer :)

And I agree, this is one of those threads that should be a sticky :)

[Sniper]

Thanks for the tip. I'll be checking this on my Raptor before it gets hot again. We fought it this summer and even took it back to the dealer to have the AC checked.

[jertour]

Checked the AC duct in our Xlite 28RKS and same as others ducts went past vents. Found some foam 1 ½
thick 18 inch wide,36 inch long in the sewing dept. at
WalMart. worked great

[Wildhorse]

I brought our 355TS Raptor home from the storage lot we keep it at to tinker this weekend. I stumbled across this thread and will probably look into taping, sealing, and blocking as others have done. But out of curiosity I didnt see in this thread anywhere where people had bypassed the racetrack ducting entirely with the slides on the AC units themselves to utilize the vents built into the cover of the unit. Because our AC's wont keep up in our Raptor as the heat builds outside throughout the day this was needed for us to even have a chance of being inside on hot days. I guess my question is really, if you have indeed used the built in vents on the AC units thenselves that blow a lot of air, but are loud, does the race track ducting once sealed and corrected for poor workmanship work more efficiently than the direct venting from the actual AC units?

We are finding that the dark tented windows on our Raptor get hot and radiate inside our trailer and are much more efficient at warming it than the ACs are to overcome to cool it down. The one at the top of the stairs at the little landing just outside of the bathroom and bedroom entrance is the worst. We simply cant have the pull down shade open, period...

[IRV2]

First I'd like to say since my post on this thread 10/25 that I have learned so much here. I almost laughed when I had the questions I was asking. Anyhow a couple of weeks ago I did finally pull the vent off only to find what others were finding, that the duct goes past the vent. I had some pipe wrap that comes on the roll. I cut serval pieces and stacked them, then using the aluminum tape I wrapped some tape on them it kinda of looked like brick. I wedged it in the duct and using the tape finished sealing inside the duct. I did both ends one in the living room and one in the bedroom.

[srvnt]

This did the trick, one on each end, the results are really amazing.

[JRTJH]

srvnt,

That looks like an open cell foam block. If it is, watch it closely. The cold air in the roof vents tends to collect condensation. Often it will push that condensation to the ends of the ductwork. If something (open cell foam) that collects and holds water is placed there, it can keep the area wet, create an ideal environment for mold and set up a problem that you won't notice until it starts smelling. So, you might want to keep an eye on it to make sure it doesn't stay wet. Closed cell foam that won't hold moisture is much less problematic.

[srvnt]

Thanks for the heads up, I will keep an eye on it maybe enclose them in a plastic bag and reinstall them

[MattHelm21]

srvnt,

That looks like an open cell foam block. If it is, watch it closely. The cold air in the roof vents tends to collect condensation. Often it will push that condensation to the ends of the ductwork. If something (open cell foam) that collects and holds water is placed there, it can keep the area wet, create an ideal environment for mold and set up a problem that you won't notice until it starts smelling. So, you might want to keep an eye on it to make sure it doesn't stay wet. Closed cell foam that won't hold moisture is much less problematic.

Would the pool noodle foam be considered closed cell?

[JRTJH]

Would the pool noodle foam be considered closed cell?

If you mean the ones that float and don't absorb water, yes they're closed cell. Some of the older "blue rubber coated" pool floats weren't closed cell foam, but were open cell (think sponge). When the outside coating cracked or deteriorated, the inside filled with water.

I suppose, as a test, if you can put it under water, squeeze it and it doesn't soak up water, it's closed cell foam. If, on the other hand, it absorbs water like the old "O-cello sponge" then it's probably going to hold water if installed in the A/C ducting.

[captcolour]

So I got around to check my Alpine which has 2 A/C units. The A/C outlets on either end of the 5th wheel are slightly towards the middle of the 5th wheel, so no dead space after the vent. Problem I see is that both A/C units use the same plenum, so if only one unit like the bedroom is on, the air is being pushed the entire length of the 5th wheel. Seems I should isolate the two systems so each can run more efficiently when only one is running. Does this make sense that they are using the same plenum?

[Bob Landry]

Did the same thing to my Outback several years ago. That with snap on solar screens keeps my trailer at 75 degrees in the midday Texas sun.

[Jcdwing]

I know this is an old thread but I have a 31 keystone passport and seems to need some vent assistance planning to look into it this weekend

Instead of buying new different vents for the existing holes why not just add a vent or two in the existing plenum? This would add additional flow.

[JRTJH]

I know this is an old thread but I have a 31 keystone passport and seems to need some vent assistance planning to look into it this weekend

Instead of buying new different vents for the existing holes why not just add a vent or two in the existing plenum? This would add additional flow.

Seems like a logical solution, but be sure you have the air volume capacity from your blower motor to support additional vents. What works on a system with 4 vents may not be as effective on a system with 8 vents. If, by adding two more vents, you decrease the volume going through all the other vents, you may not gain anything in cooling and might decrease cooling in places further from the original vents. Are the existing vents "restricting" air flow or is there another reason for the cool air problem? Check things like blocked ducting, leaking return/supply air plenum, dirty condenser, leaking ductwork (end of duct run and split/leaking seams along the duct.

[Minecoyote]

Ours was blowing into the space above the shower with no duct work for the air to flo through. the husband bought some kind of foam to put in there and formed a tunnel to direct the air through. that worked really well.. You would think with all the money we pay for these things they would build them the correct way.. Geez

[Jcdwing]

Update.

My 2017 3350 keystone passport the air conditioner was sooooo loud could hardly talk. Air somewhat squealing trying to go through the “cool down straight out opening “

First step clean up and tape the exit area of the brisk air.

Second I added another 4 inch ceiling duct. That seemed to allow more airflow reducing the pressure on the system. I will most likely add another I still have plenty of flow. I also blocked the runs at the last vents.

I know this tread started by adding higher flow ducts. But leaving in tact and adding one I feel accomplished the same.

[BamaRam]

I downloaded all of the service and installation data for my A/C unit (Mach 18) and found some performance information that may be relevant.

From ChillGrill literature
B. Registers
Supply (cold air) registers should have a minimum discharge area of 48 square inches per system, or 24 square inches per duct. A minimum of 6 is recommended.

From Airexcel's EVALUATING AIR CONDITIONER PERFORMANCE

1. Measure the evaporator temperature difference:
a. Open all discharge/ supply registers fully.
b. Tum the selector switch or wall thermostat to the HIGH COOL position.
c. Allow the air conditioner to run for at least a half an hour, longer if possible. This is necessary to fully cool the evaporator coil and saturate the unit with condensate water before beginning a temperature test.
d. Use a standard dial type or digital thermometer to measure the temperature of the air immediately entering the return air filter/grille of the air conditioner.
e. Measure and subtract the temperature of the air leaving the discharge/supply air louvers from the return air temperature. When you are testing a ducted air conditioner application be sure to measure the supply temperature at the closest register to the unit. Make sure the temperature sensing device is measuring supply air temperature only.
f. A properly running A/C unit should have a temperature difference of approximately 16 to 22 degrees. Slightly lower temperature differences are possible under extremely humid conditions. (The unit may have to run longer to remove moisture.) Greater temperature differences than 22 degrees are possible in hot dry weather.
NOTE: Restricted air flow over the evaporator may also cause greater than 22° temperature differences. In this case even though the temperature difference is greater the capacity would be less.

I checked mine and the difference is 33* so I may have a capacity problem. It cools well and the amperage is good so I'm good for now.

[mikz86ta]

I'm no HVAC expert but an a logical thinker. They don't build these for quality and function. They build them fast and with the same parts no matter what floor plan. With AC specifically, I watched enough factory videos to see they simply drop in a standard length duct and then hole-saw where they want the vent. So it's no surprise that the duct extends past.
What's bad is the lack of sealing off they do at duct joints, AC unit connections and vent openings. I resealed my duct openings and inside the AC unit. Unfortunately there's no way I can tell how well the duct sections are sealed.
And the further away from the unit, the weaker the flow. Even if I close all the vents but the farthest one, seems not that much stronger.
Like I said, no HVAC expert, but every house and business I been into, the AC ducting decreases in size/diameter the farther you get from the main unit. This creates higher flow. But the RV ducts don't seem to do that

[Steveo57]

Checking out my AC to see if I can quiet it some and optimize its operation and I found a few things. Like someone else posted above the control box and wiring in the inlet plenum was just stuffed up in there and only secured with one screw that was too long so it was just flopping around. Also found the cutout for one of the registers had been left in the duct and was blocking the air flow.

One interesting thing I noticed in the manual for mine was a requirement for register location of 5-8 inches from the end of a duct. Obviously we are seeing much more than that in most cases. Mine have 30" or more of duct extending beyond the last register.

Attached is the requirements for my unit from the installation manual.16704

[MisaLetet]

WOW! This tidbit could be the answer to my frustration with our A/C units in our 2016 Fuzion! Our rig is 43 ft with three A/C units. We spend lots of time in the Lake Havasu area in the summer time so we wanted to make sure we had adequate of A/C.

We have never felt we had decent cooling in the rig since day ONE! We rigged up a box in the bunk area to direct cool air into the main living area to no avail. Talked to the dealership on at least three occasions where they "tested" the cooling and said it was working fine.

I hope we can apply this fix!

[pitman44]

Does anyone have a link to the foam they maybe used ? Amazon or Home Depot ?


That type of foam is called sill seal. It's used on the bottom of the sill plate that sits on the foundation wall of a home. https://www.lowes.com/pd/Dow-Sill-Seal-R1-50-sq-ft-Unfaced-Polystyrene-Roll-Insulation-7-5-in-W-x-50-ft-L/1000172805


The thing I find interesting is in residential duct work the trunk needs to run a minimum of 12" beyond the last takeoff or the last register won't get very good air flow. It could be several feet longer and not cause an issue. Makes me wonder if the end of the run is closed off.

[pitman44]

I downloaded all of the service and installation data for my A/C unit (Mach 18) and found some performance information that may be relevant.

From ChillGrill literature
B. Registers
Supply (cold air) registers should have a minimum discharge area of 48 square inches per system, or 24 square inches per duct. A minimum of 6 is recommended.

From Airexcel's EVALUATING AIR CONDITIONER PERFORMANCE

1. Measure the evaporator temperature difference:
a. Open all discharge/ supply registers fully.
b. Tum the selector switch or wall thermostat to the HIGH COOL position.
c. Allow the air conditioner to run for at least a half an hour, longer if possible. This is necessary to fully cool the evaporator coil and saturate the unit with condensate water before beginning a temperature test.
d. Use a standard dial type or digital thermometer to measure the temperature of the air immediately entering the return air filter/grille of the air conditioner.
e. Measure and subtract the temperature of the air leaving the discharge/supply air louvers from the return air temperature. When you are testing a ducted air conditioner application be sure to measure the supply temperature at the closest register to the unit. Make sure the temperature sensing device is measuring supply air temperature only.
f. A properly running A/C unit should have a temperature difference of approximately 16 to 22 degrees. Slightly lower temperature differences are possible under extremely humid conditions. (The unit may have to run longer to remove moisture.) Greater temperature differences than 22 degrees are possible in hot dry weather.
NOTE: Restricted air flow over the evaporator may also cause greater than 22° temperature differences. In this case even though the temperature difference is greater the capacity would be less.

I checked mine and the difference is 33* so I may have a capacity problem. It cools well and the amperage is good so I'm good for now.


Higher deltaT indicates lower airflow. The NOTE: above states that. Could be a dirty evap coil, not enough registers, dirty blower. The first two are most likely.

[BamaRam]

Higher deltaT indicates lower airflow. The NOTE: above states that. Could be a dirty evap coil, not enough registers, dirty blower. The first two are most likely.

My unit is new and I have inspected it. It’s not dirty. I probably need more registers.

[infantryofficer81]

WOW! This tidbit could be the answer to my frustration with our A/C units in our 2016 Fuzion! Our rig is 43 ft with three A/C units. We spend lots of time in the Lake Havasu area in the summer time so we wanted to make sure we had adequate of A/C.

We have never felt we had decent cooling in the rig since day ONE! We rigged up a box in the bunk area to direct cool air into the main living area to no avail. Talked to the dealership on at least three occasions where they "tested" the cooling and said it was working fine.

I hope we can apply this fix!
Hi,
We have the unit shown in my signature block. I can tell you it will make a big difference! Yesterday, I got off my lazy butt and pulled the covers off all 3 AC units. First, I must say, I should've taken pictures, but I didn't. Anyhow, the first thing I noticed were the panels (not sure of the technical name) were just lying on their side inside the unit. In other words, the air was basically just staying up in the unit area and not really being forced into the vents. So, I untaped everything and retaped it, got things all nice and neat and lined up, reinstalled the covers, and cleaned the filters (which weren't dirty). Took a pool noodle and shoved it into each vent in the kitchen. The ducting system must have been crimped, because all of a sudden once I fired the units up, I had air coming from all 3 kitchen vents whereas, previously I had air only coming out of one! On the garage AC I noticed the heating element was not plugged in so I took care of that! Now, I know why the unit wouldn't generate any heat! Here in Texas it is hot, and I could tell the difference immediately. Sorry for the long post, but I hope this helps someone.

[Jcdwing]

My unit is new and I have inspected it. It’s not dirty. I probably need more registers.



My unit was new as well. Mine changes were initiated by the reduction of noise.

Pulling the cover and taping all the re entry was a huge help. I have a dometic brisk air and with the cold air shower shower closed it was still so much pressure that it was squealing air from high pressure.

All I can say is adding one vent helped I may add another and the vents I purchased have the ability to be shut off as well.

Everyone’s results may vary. But this was a great help to reduce noise and cooling efficiency for me. Hope it helps someone else

[Owl]

I just worked on mine today. I couldn’t get the trailer to cool down and it was getting very frustrating. Pulled the covers and found that the discharge air was blowing right back into the return and freezing up the evaporator. I also found many instances of poor taping in the ducts at the vents. Also found a dead end run of 8’ of ducting. Closed that off and redirected a couple of others. Finally it’s cooler inside than out and can actually feel the air moving. Fixed some leaks around one of the unit’s cover and that helped with noise. It’s a shame that the “professional” installation is this poor. Oh well, it’s still better than making a house payment.

[Kcorp]

I've read through this thread a few times, I just want to reiterate a fix to collapsed ductwork in the air intake lines. So the quite cool system in my Montana isn't getting the airflow it needs. The intake ducts look squished down to 1/2 to 3/4 of an inch all the way to the ac unit. I checked with a buddy's bore scope camera. I'm just trying to figure out how to wedge a pvc pipe in there to open it up. It seems like I need something flexable enough, because of the tight angles and small holes I have to work with and the fact that it would have to run all the way to the unit from the intake grills. Anybody have any ideas?

[twvette]

Note that on mine many of the ducted vents are connected together so you want to verify where they go before sealing any of them off.

Mine is a complete mess and gonna do a separate write up on it for anyone who has a Fuzion 420. No wonder why none of use can keep this model cool ...

[wiredgeorge]

Another thing that helped with cooling in my old trailer is that when I put a NEW 15K BTU Dometic Duotherm Brisk II in to replace the old 13.5K BTU, I had to remove the bottom unit. You pull the four long bolts and the metal bottom comes off after taking off the plastic cover. I noticed the outflow from the A/C enters venting to the sides and the silver foil tape was very poorly installed from the factory that directs cold air into the vents to the front and rear of the trailer. Retaped these so that air wasn't escaping into the void in the roof and retaped the dam between the intake and outflow of air and the unit performs much better.

[bacaviness]

I'm so glad more than a year later this tip is still coming in handy! When I originally posted I had no idea so many people would be interested.

A little update for us, while it did help significantly, we finally decided we needed a second a/c regardless. We decided we spent too much money buying our TT to not be 100% satisfied.

I will note that we saved some money by purchasing the new a/c off of amazon and then having CW to do the install. They charged $125 to install the one we bought, and we agreed $125 was worth my husband not having to fool with it!


Sent from my iPhone using Tapatalk

Any chance you have step by step instructions on how you did this? I’m afraid I’m going to break something lol!