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Old 05-24-2015, 12:48 PM   #519
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We left the factory tape on our vista-view windows and can really feel the difference! Much cooler with the upper windows completely blocked ... they doo provide "atmosphere" but no real vision benefit IMHO.
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Old 07-14-2015, 08:55 PM   #520
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Ducted versus Non-Ducted: An actual test- Yesiree.


After months of waiting, I have the data to compare the difference between the standard non ducted (my AS) to a ducted unit. The test unit was a 2015 27' Eddie Bauer with a single 15K ducted Dometic unit and on/off adjustable metal air vents. I used the same instrument and app to measure the sound level and measured at the same points in the trailers lounge area seat at end, middle at intake and rear at nightstand or middle end. I used the app on the iPad called decibel 10 calibrated to -4.9 to match my previous readings on my sound meter and readings on my trailer- basically the same instrument was used to compare. Here are the results:

2006 Airstream 25' with Dometic ceiling unit 11K BTU non-ducted
fan speed high
62dB front 62dB intake 61dB rear(bedroom)
fan speed low (next lower setting- light blow at vents)
58dB front 62dB intake 55dB rear(bedroom)

2015 Airstream EB 27' with Dometic 15K BTU ducted unit

fan on high
55dB mid rear by back lift gate 67dB intake 56dB at bed pillows center
fan on low
52db rear 63 dB intake 52dB bedroom

During the 35 min or so stint we were dripping wet with sweat. I took readings several times. There was a distinct difference in sound level (I just spent two weeks in my AS on the road) however, I the figures indicate how much difference.

Someone posted how slow their old non-ducted AC unit cooled. Here is some data I logged one night during my first night on vacation from my 11K unit on time to cool:

Also, during my stay the first night in FL it was 91 degrees and just starting to sprinkle when I started my AC. It was HOT. Here is a timeline of temp/humidity by by indoor meters.
Started AC 88 degrees, 86% humidity inside/
15 min: 87 degrees 62% humidity
45 min: 86 degrees 43% humidity (felt nice)
1 hr 15 min: 82 degrees 42% humidity
2 hrs: 80 degrees 37% humidity (had to turn down- too cold in trailer-got blanket!

The outside temp at two hours dropped to 87 degrees but super steamy humid.

Now, the ducted unit we ran for 35 min or so. It was not cool at 35 minutes. I had to get out. We walked out to talk a bit and as hot as it was outside today it felt cool compared to the inside.

My conclusion is that the ducted air is quieter as the record shows. At low fan there is much less difference. Regardless though, it is quieter by as much as 7dB in the lounge area and and 6dB in the bedroom. Ironically the readings at the intake were a bit higher. On low fan the difference was less dramatic. That said, there is a thread discussion about some saying it is more efficient. In that I totally disagree. We were roasting. The temp outside was 92. I have no idea the temp inside the AS but I know that after 35 minutes it was still hot. I know that I am stirring the pot but in my opinion ducted air needs two units- one for cooling ducts and distributing air and the other for blowing directly. In the heat it is too long a wait before feeling cool for me though I would like it to be quieter once cooler. I laughed when the sales guy told me that the hatch over the bed was to allow for fume evacuation for running a generator inside while driving to keep the AC running while on the road to get it cooled down before stopping. I did not know he was serious.

Would I want ducted AC? Yes, for the noise reduction. As a matter of fact, we ran the numbers for a trade just to see. I do know that I would need to stay out of the trailer until it cooled down a bit though. How long is uncertain. I believe the ducted Airstream has the same challenge as any SOB for cooling- there needs to be two units-one to quick cool directly and the other to run ducted after cooling for maintaining cool and quiet operation. I thought as much but did not post as I was uncertain until now.
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Old 07-14-2015, 10:26 PM   #521
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Great write up. My only comment would be a 25ft with 11k, versus 27ft with 15k is not comparing apples to apples.

I don't care which is better, but for the forum...

I have a 25ft with ducted, I think that is a 15k unit on the top, I promise to check! If anyone in Portland has, say a 2014 25ft, rear bed with the same type of unit on the roof, then we could get together and repeat the test. I have a 3100w generator we can use for the rest.

If anyone is interested to set this up send me a message
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Old 07-14-2015, 11:37 PM   #522
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In Farmington, pulling in after about 300 miles in 90+ degree heat, the inside temp dropped from 89 down to 78 in less than 30 minutes with the two AC units on my Serenity 30RB. My older 2009 27 FB, single unit could not have gotten the temp below 80 in the sun.

My conclusion, ducted air is much more efficient, primarily due to the thicker roof insulation, less heat loss through ceiling.

Of course two always cools faster than one, but on the generator, one unit pulls it down quickly as well on my new Serenity.

Just my opinion, but I suspect there is a problem with the previous post, would suggest checking outlet temp when AC is running to be certain it is indeed working.


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Old 07-15-2015, 06:59 AM   #523
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Ducted Air

That test pretty much concours with my dealer's assessment who said that the ducted air unit tends to cool down a heated trailer more slowly due the distribution of the air throughout the trailer. Those with the non ducted units have the blast effect where the air output is more localized thus cooling the central area of the trailer first and then spreading outward.

My SOB had ducted air and exhibited the same tendencies.

Jack
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Old 07-15-2015, 08:26 AM   #524
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Quote:
Quote:
25ft with 11k, versus 27ft with 15k is not comparing apples to apples.
It would be best to have the same unit and same sized trailer but I do not believe it is going to make that much difference. The BTU rating is not really a sound level rating and the larger trailer would need the extra BTUs to cool anyway, especially with the additional window area.
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Old 07-15-2015, 09:39 AM   #525
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Just my opinion, but I suspect there is a problem with the previous post, would suggest checking outlet temp when AC is running to be certain it is indeed working.
BTW, we checked to make sure all ducts were open and checked after about 10 minutes that, in fact, cooler air was blowing out of the ducts. I did not post to attack ducted units or owners of such. I have been intrigued with the possibility of ducted quiet air; however, a comparison is/was in order perhaps if for no one else but me as I kept wondering. I still like the quieter level of sound and now I know how much quieter. As far as GSMblue's comment that they are not the same unit, etc that is true but as far as I am concerned it is what I have and most likely the same unit is no longer used that I have anyway- like many others who traded up from one unit to another but also making comparisons to what they knew to the new AS. Naturally one study is just that, one study but it supports the fact that ducted air is quieter, at least on the ends where people reside most by 6-7dB but in the center area it was as noisy per se - no big surprise and no wounding of product claim. Low fan speed is better for both and closer in levels comparatively but I have found that not too often in high humidity could I run my AC for long on low without a freeze up.
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Old 07-15-2015, 09:56 AM   #526
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rodsterinfl - really appreciate the efforts you went to for the greater good!

FYI: I do think in 94F heat my AS takes too long to cool down... While in central OR last week, it struggled to get us down to 72F and was running a lot...
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Old 07-15-2015, 10:43 AM   #527
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So the ducted versions don't have a panel under the AC to divert all the cold air straight down into the trailer. All of the air goes into the duct work?

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Old 07-15-2015, 11:02 AM   #528
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Previous actual test ... nearly a year ago ...

Quote:
Originally Posted by rodsterinfl View Post

Ducted versus Non-Ducted: An actual test- Yesiree.


After months of waiting, I have the data to compare the difference between the standard non ducted (my AS) to a ducted unit.
What?
*** From my actual test data post mid way (pg 11-14) in this thread (and others) on 8 - 11- 2014 *** search is your friend
comparing the same model, same length, and same location .... only the A/C was different: ducted vs. non-ducted.
Quote:
... relevant post ... written first person as someone who has lived with the new 2015 AIRSTREAM ducted air for a month ... not speculation or he said, she said ...

There is no need to cycle the fan in 90+ weather to cut noise; see the numbers below. It is really quiet! We leave it on high for most of the cooling time (thermostat set to 72); however, if you might want the fan to cycle on and off with the compressor - set it to auto (either the fan or the A/C). There is no switching between ducted and any other alternative for A/C or bypass ... ducted is the only option we have with a single A/C unit for the heat pump. The furnace is still the familiar unit behind the axles at floor level with flex hose to various outlets near the floor. But talk about a nice even temperature from one end to the other with the ducted air! WOW !

Ducted Air Conditioning; Sound Level Numbers

Originally Posted by mefly2
Of course these sound level readings for this central air 2013 will be relative...but from a SmartTools sound meter app on my phone, I measure: 63 db at 6' while seated at the cushion juncture of the dinette; all a/c vents are open and fan on high. Directly under the main a/c vent and in front of stove: 84-85 db. Sitting on the bed: 65 db. So, as would be expected, the sound level drops inversely by the square of the distance (if you could hear that accurately).

Note that reducing the fan speed lowers the 6' reading to 59db; significant but not quiet nor sufficient flow to keep us cool (75) when the outside temps climb in bright sunshine.


For comparison ... Normal conversation at 3'= 60-65dB
City Traffic (inside car) = 85dB

As promised ... we finally took a break from enjoying / playing in our EB w/ ducted air to get the following ducted air conditioning sound level background readings;


* fan on high, compressor running *

Seated at the cushion juncture: 54-55 db; down from 63 db / 59 with fan on low; reduction of 8-9 db.

In front of stove directly under inlet for ducted air: 60 db; down from 84-85 db; reduction of 24-25 db !!!

Sitting on the front bed: 54-55 db; down from 65 db;
reduction of 10-11 db.

Even by this unscientific means, those difference numbers are significant and dramatic for sound reduction.
The ducted air is also very effective in cooling (and heating) both ends of the trailer (and even the Head).


It is really now quite amazing that we can be sitting in cool comfort and listen to Pandora or a movie at the same time as the AC is on with the fan on high. I can now talk to my wife when she is in the galley area under the ducted air intakes and not even need to raise my voice to communicate. It eliminates the stress of the loud A/C background noise when inside the AS trying to do much of anything other than sleep... we spent much of last weekend just sitting inside of the Eddie Bauer listening to the quiet while the outside temps were above 90 F. Do we like the ducted air and is it worth the depreciation on our trade in ??? YES !!! Emphatically; however, YMMV
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Old 07-15-2015, 11:23 AM   #529
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Originally Posted by rodsterinfl View Post
It would be best to have the same unit and same sized trailer but I do not believe it is going to make that much difference. The BTU rating is not really a sound level rating and the larger trailer would need the extra BTUs to cool anyway, especially with the additional window area.
Agreed; see my post above. Otherwise, too many variables are introduced for objective comparison. Subjectively, we know that ducted is quieter and more efficient at cooling as well as warming (via heat pump).
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Old 07-15-2015, 11:42 AM   #530
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Yes, see your repost and found it at #184. I missed it somehow. I was working for so long trying to find a ducted model (took nearly three months) that I did not return to read all the posts posted since.

Your figure under the older unit intake is high but the equivalent to a whisper (26db) Was the unit blowing down on the instrument? The main thing is that it is quieter but we are beginning to measure that difference. Some have said it was completely silent, others no different. We would probably find some differences between padded and non-padded ceilings as well as there is a bit of vibration involved. I agree with you except for the efficiency part as it is indirect airflow distributed/divided that has to equalize first as I experienced yesterday. I had the heat pump and removed it for the new air distribution unit. The nice thing though is that there is no adjustment of airflow or very little needed as opposed to a non-ducted unit (I have to close the vent directed at the front to equalize the rear temperature).
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Old 07-15-2015, 11:55 AM   #531
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Rodster-
Some have had luck with the new adjustable individual opening / vent covers to control and equalize the flow. We have not yet found the need for the spendy little buggars.

And, yes, the ducted models are now the "hot" item on the dealers lots ...hard to find in some cases. There is a new found demand for the 2015+ models with ducted.
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