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AC silencer


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My rear ac in my bedroom is noisy when we sleep so looked at the Wacko Silencer for $200 and I didn’t want to spend that much money so I decided to make one. I looked at some you tube videos to see how it was made and found some scrape wood I had and put it all together and installed it today. I was very happy with how much it reduced the noise by a lot. Here are a few pictures if you want to try and make one.
 

 

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I run the front air a) when I have shore power and b) when the DW is with me.  Very tolerable. 

But that is a nice design. 

I made a set of baffles for the propane heater.  It's better without restricting air flow much.  Drop ceiling tile is a good sound absorber (wish I used it). 

- bob

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Very nice.

I built some many years ago. A bit crude but very effective. When building mine I made the opening on the end versus down. Facing that opening away from seating area really helped.

I now have two of the Wakos. They are not quite as effective as my home builts but look much better and the air filter alone is a huge bonus. We full time so have to clean the filters often.

Taking four screws out to get the shroud off has been a pain so I fashioned some wing nuts onto screws and now can take them off quickly. The filters go into the shower and shampoo cleans them nicely.

I have experimented a bit with the Wakos to add another director for the intake but it has not been a priority.

When building my own I tried hard to add my own household-type filter so I could slide them in. The household filters are very restrictive so were not viable. I did not try any of the rather expensive household filters you can remove and clean. They might have much less restriction. Finding one 12x12 could be a real problem Or one close to that. 

One end of my covers allowed plenty of airflow. So approx 14 inches by two inches was plenty of opening.

If I could have incorporated a slide-in filter made of the same material as the Wako it would have worked perfectly and I would have tried to go into production. 

My wife was very patient with all the whittling of foam and tape and the ugly prototypes. The final product was decent and some folks here may have seen them. 

The talent available in this group is amazing. If someone has a 3d printer it might be easy to make the rails and a slide-in slot for a filter. 

The cover of mine was lined with noise-dampening material. The stuff that you peel the back off and the material is covered with silver smooth stuff. The material is thin but heavy. The material appears to be a tar-like substance.

Using that same material on the outside housings of my floor furnaces and a couple of other simple mods the sound dampening was probably 6 DB. I didn't measure it. They are hardly noticeable now.

Since you are working on the ACs be sure to address the intake area and clean up that airflow as well as the output part. 

You need to cover any parts that used to be able to drop air straight out and down.

Drop a few ceiling registers and see how deep they go into the channels. Mine had not been cut to size at the factory and extended into the ducts by at least an inch. The air had to work to get up and down into the outlets. 

One ceiling vent had virtually zero air coming out. It is now one of the best in the RV.

2008 Endeavor

Edited by myrontruex
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I like it a lot Mike. Is the beige/white panel just an 1/8" Luan or something similar? I can't quite tell what the materials are. My bedroom is horribly loud but $200 seems a bit stiff for the commercial product. I talked to Wacko about a 2 years ago and at the time he didn't have a product that would work with a finished register like you have ( as well as mine ). Seems you solved it, just delete the finished register. 

Here I go again. Time to get my prototyping hat on!

Ken

 

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I used PVC molding I had already that I got from Home Depot 

https://www.homedepot.com/p/2448-1-1-4-in-x-2-in-x-8-ft-PVC-Composite-White-Brick-Moulding-0244808012/100077259

And yes that is 1/8 laun I had also. I just used a router to make the groves. I had some felt left over that is used for a base for laminate flooring and that is my sound deadening material. I found spray paint that matched the off white ceiling pretty close from Rustoleum called ivory bisque and that was at HD also. 

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Mike, I am curious about your actual AC setup. How big is that register? Is that a full-size filter of some sort?

I would appreciate a picture of what is hiding behind the filter. I'm trying to visualize how the roof AC unit draws in the air via that huge register.

My ACs are the Penguins. The intake and output air flow would be physically just a few inches apart if the air was allowed to drop straight down as was allowed with the original registers. You could slide some louvers open and most of the air would be directed straight down. This alone caused a lot of noise. The original ceiling registers are abandoned and the downward airflow is completely blocked thus forcing all of the air through the ceiling register. 

Even though I have the Wakos because they are so clean looking and the intake filter is a very good filter I may attack this issue again. 

The PVC stuff looks great and gives me some ideas. I like the inset of the luan versus a flat top cover. 

My goal would be to have one side/end left open to draw air from there versus the bottom of the cover. (Nice slots you routed).

Being able to direct the input away from the living area or sleeping area helps a lot. Every DB counts for sure.

IF one could stand the aesthetics, a deeper muffler might allow at least one baffle. That is something like a muffler. 

I have done this successfully with the floor heaters. Just placing a baffle in front of the intake area so the air has to go around to get to the intake keeps the noise down drastically. It does not inhibit any airflow. Our RV has some decent real estate to work with but some past RVs were small and may not have had the room to add such baffles. 

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On 7/23/2022 at 1:22 PM, Georgia Mike said:

I used PVC molding I had already that I got from Home Depot 

https://www.homedepot.com/p/2448-1-1-4-in-x-2-in-x-8-ft-PVC-Composite-White-Brick-Moulding-0244808012/100077259

And yes that is 1/8 laun I had also. I just used a router to make the groves. I had some felt left over that is used for a base for laminate flooring and that is my sound deadening material. I found spray paint that matched the off white ceiling pretty close from Rustoleum called ivory bisque and that was at HD also. 

So by the looks of the pictures you have left about 1/3 of the unit open for the air return. Am I on the right track there? Because I am a proto-typer I swung my cover down on the hinges and placed a piece of throw rug about 2/3s the size of the return air ( your Luan ) between the register grate and the factory washable filter which is quite rigid. I closed it up and ran it for a day and sure enough it baffled things greatly. 

Always messing with the A/C cooling in my coach I was always quite jealous that Monaco never thought to cool the bathroom. There is a vent in the hallway  between the bathroom and the shower that didn't add a lot to the coach cooling and did nothing for the bathroom. One day I fashioned a little air chase out of cardboard that covered the vent and went a foot or so across the ceiling, over the bathroom door that was already cut a few inches short for ventilation. Oh wow, looked awful but worked great. I left it like that for months trying to figure out how to make it look nice. One day it came to me. I replace the cardboard with a clear plastic vent extender meant to bring A/C into a room under a couch. It looks fine for a 20 year old coach and I have great cooling in the bathroom. 

A little proto-typing and patience goes a long way. 

 

https://www.amazon.com/gp/product/B07WNPQXZ9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Thanks again

 

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I bought wackos for my old coach. They might technically be quieter but I was not impressed. 

I have a nice ceiling panel in the new coach up front and that helps a lot. The bedroom is still noisy. I am going to try to make something myself for the rear AC. I thought the wackos were going to be a little more high tech than what they are.  Some owners seem to love them, did not do much for me. Might depend on the ducting of the coach. 

 

 

Edited by rustykramermetalfab
grammar.
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18 hours ago, Grampy OG said:

So by the looks of the pictures you have left about 1/3 of the unit open for the air return. Am I on the right track there? Because I am a proto-typer I swung my cover down on the hinges and placed a piece of throw rug about 2/3s the size of the return air ( your Luan ) between the register grate and the factory washable filter which is quite rigid. I closed it up and ran it for a day and sure enough it baffled things greatly. 

I used the plenum itself as a baffle, if that makes sense.

I cut some blocks of acoustic foam and wedged them in on either side of the duct running through the intake plenum in the forward section directly under the blower intake. So the air goes up in the rear part of the plenum, turns forward above the foam blocks and then up into the blower intake. 

Then I blocked off the rear half of the filter like you did with the piece of rug. So the air enters the plenum through the front half of the filter grate, turns to the rear, goes up into the plenum and then back forward to the blower intake.

That cut down on the blower noise, to the point where it's more noticeable from the supply duct.

Cheers, Walter

Edited by wamcneil
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1 hour ago, wamcneil said:

I used the plenum itself as a baffle, if that makes sense.

I cut some blocks of acoustic foam and wedged them in on either side of the duct running through the intake plenum in the forward section directly under the blower intake. So the air goes up in the rear part of the plenum, turns forward above the foam blocks and then up into the blower intake. 

Then I blocked off the rear half of the filter like you did with the piece of rug. So the air enters the plenum through the front half of the filter grate, turns to the rear, goes up into the plenum and then back forward to the blower intake.

That cut down on the blower noise, to the point where it's more noticeable from the supply duct.

Cheers, Walter

Way back a few years ago, there were many home brewed systems.  The one thing to remember.  If you reduce the air flow on, at least, a Dometic system….as in running dirty filters, you run the risk of a higher Delta T.  Now that sounds great….more cooling.  OPPS, per Dometic and the techs at the LD seminars, that puts more strain on the system and you actually get less cooling.  Being a skeptic….and parked in the LD lot during almost 100 degF days…I measured the Delta T.  I also have an HVAC or air flow meter that has a fan that measures the FPM and temperature.  I cleaned the filters and dried them.  Then let it run a bit and the air flow was higher and the Delta T back within the Dometic spec.  I did cool off a degree or 3 cooler.  Now, I have a 40 and only two 15K units.  The longer ones with the additional 13.5K are much cooler.  Do the BTU/Foot calculations.  Therefore, I have to get the most efficiency to stay comfortable.

One MIGHT want to test or do the Delta T evaluation. If you go up, say 10% over the Delta T spec, odds are…you are restricting airflow.  Not really good for the unit, but if you have 3 AC’s, you will probably stay cool…but long range…??

 

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2 hours ago, Georgia Mike said:

If i am not mistaken the range should be between 15-20 degrees cooler correct? I need to run a test on all my units to see how they are preforming.

That's what they say!

I recently spent half a day on the roof cleaning each of my evaporator / condensor coils with spray cleaner. Probably the first time it's ever been done. I also made sure the foam dividers were properly glued in place.

Testing after resulted in 25-27F delta.

Not bad for 15yr old units. Still think they are overpriced junk compared to modern residential window units!!

Edited by 96 EVO
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1 hour ago, 96 EVO said:

That's what they say!

I recently spent half a day on the roof cleaning each of my evaporator / condensor coils with spray cleaner. Probably the first time it's ever been done. I also made sure the foam dividers were properly glued in place.

Testing after resulted in 25-27F delta.

Not bad for 15yr old units. Still think they are overpriced junk compared to modern residential window units!!

The Lazy Days techs and the Dimeric techs might disagree with you.  Normal for those units is in the low 20….assuming you have let the rig stabilize for an hour or so and not opened any doors or run laundry or taken hot showers.  The high Delta T is a sign of restricted air flow, most commonly from dirty filters or modification to the filter or such.  My 09 Camelot’s Delta T will increase drastically if the filter is dirty.  I tested that out in 2010 at Lazy Days and talked to the instructor for the seminar the next day as I went back again.  He said Delta T over 25 were not good….the adage was….say 20 is the spec and it may be a bit higher…memory.  But low in the 16 range is bad…High in the 25 range is bad.

Do some research….and look at the Domertic manuals or the “tech trouble shooting one”.  
May be wrong….but all the comments from RV techs on the other forums say that, for you age rig…20 is a good number….say plus or minus 2 degF.

 

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1 hour ago, 96 EVO said:

That's what they say!

I recently spent half a day on the roof cleaning each of my evaporator / condensor coils with spray cleaner. Probably the first time it's ever been done. I also made sure the foam dividers were properly glued in place.

Testing after resulted in 25-27F delta.

Not bad for 15yr old units. Still think they are overpriced junk compared to modern residential window units!!

Ben, this is on my list, curious what you used as a spray cleaner? 

Thanks!

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23 hours ago, Tom Cherry said:

  

May be wrong….but all the comments from RV techs on the other forums say that, for you age rig…20 is a good number….say plus or minus 2 degF.

 

Re-tested mine today after an hour of running.

Mid and rear 22F delta. Front about 26F.

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16 minutes ago, 96 EVO said:

Re-tested mine today after an hour of running.

Mid and rear 22F delta. Front about 26F.

Good and bad.  Look for restricted air flow.  If not filters, then air leaks around the various outlets.  Check the plenum for leaks,  I had to reseal all mine with HVAC foil  tape.  Next up, per the “experts”.  Some of the ductwork can sag or droop.  Folks have removed the louvers and then used lights and mirrors or inspection camera to verify the shape and structural integrity of the ducts.  Enterprising ones have actually fabricated aluminum strips or supports and put them in place to support them. That improves the flow and dropped the Delta T into the good zone.

Just all that I read and the various fixes and results.  

Good Luck

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On 7/25/2022 at 9:52 PM, Tom Cherry said:

The Lazy Days techs and the Dimeric techs might disagree with you.  Normal for those units is in the low 20….assuming you have let the rig stabilize for an hour or so and not opened any doors or run laundry or taken hot showers.  The high Delta T is a sign of restricted air flow, most commonly from dirty filters or modification to the filter or such.  My 09 Camelot’s Delta T will increase drastically if the filter is dirty.  I tested that out in 2010 at Lazy Days and talked to the instructor for the seminar the next day as I went back again.  He said Delta T over 25 were not good….the adage was….say 20 is the spec and it may be a bit higher…memory.  But low in the 16 range is bad…High in the 25 range is bad.

Do some research….and look at the Domertic manuals or the “tech trouble shooting one”.  
May be wrong….but all the comments from RV techs on the other forums say that, for you age rig…20 is a good number….say plus or minus 2 degF.

 

For my clarification, the delt T was between the return and vents?

 

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