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Old 11-10-2020, 09:02 AM   #1
Winnie-Wise
 
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Location: Sugar Land, TX
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Improving A/C Duct Air Flow and Reducing Noise

Recently, we've seen multiple YouTube videos posted about a new product from RV AirFlow that claims to improve air flow, improve cooling and reduce noise.

They've developed what appears to be a styrofoam insert that is installed into the roof air conditioning plenum the routes all air into the ceiling ducts, eliminating backflow (cold air from the A/C being sucked immediately back into the return), and reducing noise (because the insert adds sound insulation below the fan.

It looked like a great and simple idea.

We were getting ready to order one - and then went out to measure the A/C plenum in our 21VD and determined Winnebago's configuration doesn't match the specific measurements used to build RV Airflow's product.

I reached out to them, and they confirmed the current product works with some Grand Design models (they have an exclusive agreement allowing Grand Design to install their product at the factory) and that they wouldn't start working with Winnebago until next year.

Rather than waiting until then, I thought I would make a pass at a short-term solution, and if that wasn't good enough, we would purchase the RV AirFlow product when they had a version that worked with our View.

Using HVAC tape and a roll of duct insulation (sticky on the back) from Home Depot (at a fraction of the cost of RV AirFlow's product), I spent less than 2 hours yesterday working on our A/C plenum.

I removed the outer face plate and the inner face plate (4 phillips screws each).

I noticed the divider between the output and input sides of the plenum had already started to flop over into the input side - cold air was being sucked directly back into the A/C unit - which reduced the air flow actually going into the coach.

I removed the divider and reinstalled it in the correct position using the HVAC tape - taping it to the top and sides of the plenum - on both sides of the divider. One side of the divider is unfinished - I placed this on the bottom (where it would sit ontop of the inner face place) and used HVAC tape to seal that bottom.

Using HVAC tape, I then sealed the output side of the plenum underneat the fan. This eliminated some small air gaps where air was leaking.

The next pass was to cut the duct insulation and completely cover the inside of the output area of the plenum, leaving holes for the fan (in the top) and the two side ducts. I then used more HVAC tape to seal the edges of the duct insulation.

On the top side of the inner faceplate, I covered the area under the output side of the plenum with duct insulation - closing off the air dump vents that are part of the A/C unit - which will force 100% of the air from the A/C into the ceiling ducts.

I installed the inner faceplate and then turned on the A/C system in FAN HI mode. I added some HVAC tape over the top of the screws on the output side, since that area had small air leaks - and with the increased pressure inside the plenum, since it was now sealed and forcing air only through the ducts, the small air leaks could be heard when standing under the A/C.

I also installed a layer of the duct insulation to the outside of the inner faceplate, on the output side of the plenum (where there is the large hole intended to provide air to the dump vents). I did this to provide additional sound insulation, and also to ensure no air was working out underneath the duct insulation installed inside the plenum.

I also put my hand into the input side of the plenum and felt around the divider to verify there wasn't any air leakage from the output side of the plenum.

And then reinstalled the outer face plate.

Since I didn't make any quantitative measurements on air flow out of the ducts or measure the sound level, I can only provide subjective results.

After doing this work, the fan noise seems much lower and the air flow out of the ceiling ducts seems much better. I also suspect the air conditioner will cool better, since 100% of the air flow is now going into the ducts - eliminating any leakage that was going directly back into the air conditioner.

We'll go on our first trip with the improved A/C this weekend, and see if it really has had an impact.

While this requires a little more work than installing the RV AirFlow product, their installation does have one step that could pose a challenge to most RV owners - they require remove the 4 long bolts holding the air conditioner onto the roof - and actually recommend shifting the air conditioner, if needed, to get everything to line up with the holes they have in their product. And then when you reinstall those bolts, you're supposed to torque the bolts to the level recommended by Coleman - something most owners won't be able to do without purchasing an extra tool.

If the changes we made are "good enough", they can be done with only a screwdriver and scissors - and doesn't risk moving around the air conditioner on the roof... Plus at a much lower cost!
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Old 11-10-2020, 09:09 AM   #2
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Excellent writeup and great tips for improving air flow. ON the Vita & Porto I found the air channels go way past the vents. So I blocked the air channel extensions off with Styrofoam where the air goes no where. I also payed close attention to the channels coming off the main unit. I found they had not been cut out properly which was blocking air flow to the vents. The main idea is to have as few obstructions as possible for air flow and no leaks.
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Old 11-10-2020, 11:44 AM   #3
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I saw a video of someone fixing the porting on their interior AC years ago. It's been done before by others. Good that you saw it, and decided to DIY it. Saved you a ton of money and grief, for sure.
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Old 11-10-2020, 02:13 PM   #4
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I watched multiple videos on making the same changes before attempting it.

And suspect that DIY may be good enough - and much less expensive than buying something like the airflow product.

Grand Design has recognized the A/C plenum problem - and is now installing the airflow product in their new RVs.

With such a poor design - Winnebago really should follow Grand Design's strategy - and implement a solution at the factory.

The A/C was so loud in our 21VD, that with the stock TV at 100% volume, we still couldn't hear it when the A/C was running on lo fan... And the ceiling ducts don't provide enough circulation to cool the RV in the Texas heat...
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Old 11-26-2020, 02:22 AM   #5
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Great ideas, and I will certainly check ours out. However, might anyone have any pics of the process or a link or two to some good videos on the subject?
Thanks
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Old 11-26-2020, 06:21 AM   #6
Winnie-Wise
 
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This video illustrates the issue with the divider.

The plenum design for the divider allows it to be pushed relatively easily into the return side of the plenum, causing air gaps that forces the output air from the fans immediately back into the return side - robbing the coach of much of the circulation.

Once you have the covers off, using a combination of HVAC tape (not duct tape) and duct insulation (with sticky back), you basically tape the divider into place on both sides to prevent it from moving, and then using a combination of the tape and insulation strips cover the entire inside of the output side of the plenum (including blocking the hole on the plastic cover going to the air dumps in the cover), leaving holes only for the fan output air and the two side ducts.

Once you have the plastic covers off the bottom of the unit, it should be easy to see what needs to be covered.
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Old 11-27-2020, 01:01 AM   #7
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Thanks, love this guys videos. Very easy to follow and practical tips and tricks of the trade.
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Old 12-01-2020, 02:16 PM   #8
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An update with pics

Well, I pulled the covers off of both of my ACs and thought I'd give a report on how it went. I've included pics.

Disassembly is as easy as it appears, on mine, there are the four screws around the perimeter and three smaller ones, under the filter cover. Remove all of them and it drops right down.

What I found on the inside was the interesting part. Although nothing was out of place, meaning that the parts (baffles?) in question were in place and just need securing, the AC was filthy! The piece of sponge rubber that passes as a filter (and I keep it clean(!), is a joke. The only thing it filters is small animals.

I had on hand a small shop vac, a radiator brush and an air compressor and used all three. I first used the vacuum with a soft brush attachment and gently vacuumed the coil/condenser(?). I then went over it with the radiator brush, and vacuumed again. Then on the squirrel cage blower, I used compressed (low pressure) air and removed the dirt from the fins.

I then took some (window and door) spray foam and filled in a couple of cavities in the Styrofoam from manufacturing. I'm not expecting any trouble with the wiring and if need be, the spray foam should come right out.

Last I taped everything in place as described in the previously mentioned video. Might not be a pro taping job but I'm sure it will work.

As a side note, I suspect that the flow through my AC was restricted more by the amount of dirt than by any amount of deviation of the baffle. Final note is that the front AC was 10 time more dirty than the rear. The rear took no time to do.
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Old 07-08-2021, 07:16 AM   #9
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rprochnow - Thanks for the detailed description of your AC mod in your new View. We too have been bothered by the noise level from the AC, and the poor flow distribution in our '21 View.



After eight months of use, what is the verdict on the success of your mod? Did it make things quieter and are you happy with the flow performance?


Cheers,
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Old 07-08-2021, 08:06 AM   #10
Winnie-Wise
 
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The improvements have worked well, but even with the improvements the A/C isn't strong enough to fully cool when the outside temps are above 100...

When I was checking the system while the A/C was running, I noticed air coming out of the seam between the trim and the roof in front of the ceiling exhaust fan. I took that trim piece down and added some insulation and tape to better seal that area and route all of the air to the overcab vent, rather than let it leak along the entire trim piece.

Though I doubt that improvement will do much to help when the outside temps are very high...

I also restored air to the air dump vents - so that while we're driving in high outside temps, we can run the generator and dump more cool air into the coach, combined with the Sprinter A/C running on MAX - and that has helped to bring the temps down.

But the bottom line is that the unit isn't large enough to bring the temps back down into the 70s when the outside air is 100+...

However, the improvements have helped lower the noise level and still seems to do better than before the improvements (when a lot of the air was recirculating inside the unit and not getting into the coach).
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Old 07-08-2021, 11:54 AM   #11
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rprochnow: I applaud you determination to achieve maximum cooling. And today I read your conclusion:

"The improvements have worked well, but even with the improvements the A/C isn't strong enough to fully cool when the outside temps are above 100."

This is the situation will all RVs big and small. And here's how I solved the problem in my RV:

* I added and also hid a 8,000 BTU portable AC behind a cabinet door... which you can probably do if you have 14" wide cabinet under a window; or maybe you can give up that space and go buy a free standing cabinet at HD or Lowe's if you want to hide it in a 16X24x30 cabinet if your RV does not have cabinet now.

For more information you can do a google search by typing this in your google search bar imnprsd 8000 BTU portable AC site:winnieowners.com
or you can type imnprsd 8000 BTU portable AC in the Winnebago search bar above.

PS I also explain how I ran a separate extension cord to my power center so I don't have to run the AC off my RV 30/50A Service -- unless you want to. And since this portable AC has a built in "soft start" you might be able to run it with your other AC even on a small generator. TBD. I also don't recommend you leave a portable AC "freestanding" with a long (HOT) exhaust hose venting out a window for a number of reasons. Further, the key to portable AC efficiency is to have as short and exhaust hose as possible.
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Old 07-08-2021, 12:41 PM   #12
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So I take that this modification only is needed if you have multiple ceiling vents for your air-conditioner? I own a 2019 1706FB, that only has the direct down vent below the air-conditioner body on the roof, so I don't think this would be needed by myself, right? There is no air conditioner duct work to the rest of the trailer...only conditioned air enters directly below the out-side unit. Correct?
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Old 07-08-2021, 01:18 PM   #13
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Adding a portable AC is in addition to your existing AC roof top ACs.

Adding a portable AC has no connection to your existing ACs.

Adding a portable AC will cool our RV down much better and with your existing AC system you should be comfortable in 100F weather.

You just need to modify a cabinet you already have one or if you have room you can add one. ...And I'm guessing that if you place the portable AC under the edge of a window you can drill through your wall and will not hit any studs.

I recommend you buy a stud finder to make sure. And If you go to the forum thread referred to above, you can see all the steps involved.

This upgrade is awesome. And with 8000 more BTUs of cooling in your RV, big or small, you will be comfortable in 105+F weather. Note: Next month I will be in 110F weather and that will be an even better test, but one thing is sure now, I am now very cool and it's even too cold at times when the OAT is less than 90F. So, I turn down the fan speed... at 90F in dry heat!!!

And if you don't have the skills or tools, but you can plan a trip to Rocky Point, Mexico... 1.5 hours south of the Arizona-Lukeville border, I would buy the AC at Lowes, and the 6" vent on Amazon, and I would go the The Reef RV Park and let Carlos install it for you and paint your outside wall. (See thread I referred you to for more information on this option and take a vacation while Carlos and his crew treat your right!)

Here's that link for body & paint and AC repair: https://www.winnieowners.com/forums/...ew-358003.html
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Old 07-08-2021, 01:30 PM   #14
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Quote:
Originally Posted by Sun_Seeker View Post
So I take that this modification only is needed if you have multiple ceiling vents for your air-conditioner? I own a 2019 1706FB, that only has the direct down vent below the air-conditioner body on the roof, so I don't think this would be needed by myself, right?
Yes, that's correct. In a 17 ft travel trailer there is only the A/C unit sticking through the ceiling and a large "air dump".
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Old 07-08-2021, 03:00 PM   #15
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In a View or Navion, there isn't much extra space inside the coach to add a second air conditioner.

We've found that running the Sprinter engine with the A/C on MAX for a few minutes, along with the coach A/C on high - can help bring the temperature down a little faster.

But when the outside temps were 105-108, there wasn't much we could do to keep the temperature from getting up near 90 inside - and running the Sprinter for a few minutes brought the temperature down a few degrees, but once the Sprinter engine is off - the temp would start climbing again until the sun started to go down.

Between the insulation, large areas of glass and the size of the A/C unit - there probably isn't much else we can do - once the plenum inside the A/C unit was properly sealed.
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Old 07-08-2021, 05:49 PM   #16
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Yah... I was afraid of that. I don't know our your floorplan, but I'm sure very inch has a purpose already.

THINKING OUT LOUD

A) You would have take space away from your closet, which is already is too small I know.

B) You would have to find a space, any space and try to utilize it. Like under the bed, but you can't operate a portable AC meant to stand upright and lay it down. On the other hand, they make industrial ACs that look like a small box; and maybe one of these can be utilized where the hot AC exhaust can be ported thru the floor?

C) FANS ARE A GUY'S BEST FRIEND TOO!

Keep brain storming!
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Old 07-11-2021, 10:49 AM   #17
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If not being used as a bed, the largest available space (in our D) is the overcab bunk, which also has 2 110 outlets.

When the slide is out, there is some space between the back of the driver's seat and the extended dinette foot rest.

Otherwise, Winnebago has found a way to utilize almost every cubic of space - while providing a lot of open floor space to move around with the slide out.

Running the main or bathroom exhaust fans won't help, because any air that is pulled out is replaced with hot outside air - and with the coach closed, the fan(s) will struggle to pull much out of the coach anyway...

However, we did find some benefit in running one or both of the exhaust fans while the coach A/C is running AND the engine is running with the Sprinter A/C set at MAX - which does pull in outside air and cools it down.

Though realistically - if the outside temps are (well) above 100 degrees outside - with clear skies and no shade, we probably shouldn't expect to keep temps in the 70s inside.

Running a circulating fan inside might help some - though that probably won't bring the temperature down - but it should feel a little cooler with increased air flow and do a better job of mixing the cool and hot air pockets inside the coach.
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Old 07-11-2021, 12:34 PM   #18
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You might look on YouTube for some ideas on how and where to add a mini-split-AC. Here's one for some ideas:

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Old 07-11-2021, 01:56 PM   #19
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I don't know what Ford rates their E450 cab air conditioning system at, but I'll guess that it's considerably greater than our coach's 13.5K BTU rooftop air conditioner.

Running both systems at once while parked out in the middle of nowhere in the Texas Panhandle in August in triple-digit temperatures - easily cooled down the coach very fast and soon too much. After a few minutes we shut off the idling V10 engine and were able to be comfortable with just the generator powering the rooftop air conditioner. However, probably this worked because our RV in only a 24 foot Class C.
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Old 07-15-2021, 10:42 AM   #20
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Hello again – I’m going to loop back to the rprochnow’s original post regarding the new View’s Coleman Mach 10 air conditioner and its performance and noise. We’ve had the same issues, and were mainly concerned with the noise and the inability to carry on a normal conversation while sitting at the dinette table.

Reading rprochnow’s post and description of his mod, along with recent online info from the Fit RV and the Why Wait YouTubers, I recently had a look under the cover panels of our Coleman Mach 10 in our View. With only a couple of days to look at this before hitting the road again, I concentrated on the noise issue that others seem to have improved.

As rprochnow did, the Fit RV mod using the “RV AC Silencer” blocks off the cool air dump with HVAC tape, in an effort to quiet the flow.

This seemed to work for them, and based on what rprochnow has described in his mod, this worked for him as well. As indicated, of the two plastic face plates on the Coleman Mach 10, the cold air dump can easily be blocked off if the second plate is taped off with HVAC tape, from the inside, to ensure the cold air flow just exits via the two ducts that feed the overhead vents. (Both of these face plates are easily removed by four screws.) For me, with the inner plate cold air dump duct taped off and reinstalled, I sandwiched some foam material right below the tape job, as a damper, and then reinstalled the exterior cover plate. (As I was doing this, I noticed that the dividing “wall” between the warm air intake and the cold air exhaust was covering up about ¾” of the ducts to the ceiling vents, not allowing the maximum flow to enter the ceiling channels. I moved the “wall” over a bit to allow more flow.) When I fired up the AC I was a bit encouraged that the removal of the cold air dump does indeed quiet things down somewhat, as the Fit RV reports. Now, this is all old news to this forum, but here is the reason for my writing today – I went back in to see if I could quiet things down on the INTAKE side as well - and had a lot of success in the process.

A photo of the intake side of my factory installation is attached at the bottom – a bit of a rat’s nest, and a source of lots of intake turbulence that, evidently, results in lots noise energy!

I spent some time grouping all of the yellow control wires together, carefully bundled them together tightly with zip ties, and moved the new cable off to the side. Also, I moved the white temperature sensor wire completely away from the intake altogether - generally trying to make an unobstructed path for the intake air to flow. When I put the two face plates back on, and fired up the AC, I was amazed at the difference these minor tweaks had made. The nose level has dropped considerably, so much to the point that my wife and I can now sit at the table and carry on a normal conversation. (I did a sound level test using an App called SoundMeter, based on what James did at the Fit RV, and got results a bit less than what he recorded in the Ekko). For the first time ever in this RV, we are using the air conditioning full time - and even sleep through the night with it on now.

All that to say, if your air intake on your unit is obstructed with lots of wiring, it might be worth spending some time to organize it and move it out of the way the best you can. It worked really, really, well for us to reduce the noise level.

Next up will be the task of doing what was reported previously by rprochnow – ensuring a smooth cold air path to the overhead ducts to boost their flow – but that will have to wait until some down time.

The folks at Why Wait YouTube channel have gone the route of optimizing the flow to the vented duct delivery ports using foam board, essentially emulating the RV Airflow product.

I might try a version of this one as the next phase of my AC project, someday.


Cheers,
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