# DC Exhaust Muffler....Well....Kind of.



## fivecodys (Dec 2, 2013)

MY DC system exhaust vents directly outside after SDD (No Filter). I have been very happy with everything except for how loud the exhaust is outside










The wife said it was too loud and she could hear it clearly when the front door is opened.

I was reading a post yesterday and this article by Bill Pentz caught my eye: http://billpentz.com/woodworking/cyclone/muffler.cf

Bill was building a muffler for his DC system and a friend offered a simpler solution.

The solution was to use insulated flexible duct-work to reduce the noise level of the exhaust.

Hummmm….....

So I stopped at Lowes on the way home and bought a chunk of 6" insulated flex hose and I replaced the 6" HVAC duct with it. Here are my results.

Before: 6" Standard HVAC ducting: 80 decibels measured outside near the vent.
After: 6" Insulated Flex Hose: 68 decibels measured outside near the vent.

Wow! What a difference. It even passed the wife test.

Here is a before and after pictures



















5" exhaust off blower going to a 5"-> 6" HVAC adapter (hidden in insulation) and then flex hose to 6" Dryer vent.

It's a little fluffier but no big deal.

Anyway, I thought this was interesting.

Have a great day!


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## ibewjon (Oct 2, 2010)

I am surprised there are so many complaints about DC noise. I have a Jet pleated filter on a 2 hp machine. The exhaust stays in the shop because of heat loss. I do not have a cyclone. The decibel level of the machine running is about 70-71 db, the level of normal conversation. I am in a small shop and the sound doesn't bother me. Why are some systems so loud?


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## jon54 (Sep 21, 2009)

I've been considering venting directly outdoors for some time. How much dust is actually vented? I haven't converted my HF 1.5hp DC to a cyclone yet, but would like to do it as a summer project.


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## fivecodys (Dec 2, 2013)

> I ve been considering venting directly outdoors for some time. How much dust is actually vented? I haven t converted my HF 1.5hp DC to a cyclone yet, but would like to do it as a summer project.
> 
> - jon54


I don't see any dust outside the vent Jon. I'm sure there are fine dust particles but I see no evidence on the surrounding plants so it must be very fine. The SDD really does a nice job of collecting as long as you set it up correctly. I read that having the input to the SDD straight for at least 5 feet was very beneficial to the airflow inside the cyclone and helped it separate the dust better. Since I was using a small blower I wanted to make it as efficient as possible.
So far I think I have accomplished that. I have a build article here on the forum where you can see what the other Lumber-jocks contributed. They were very helpful. https://www.lumberjocks.com/projects/388617


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## pintodeluxe (Sep 12, 2010)

I did basically the same thing with my tempest cyclone. Seems to make a marginal improvement in volume.


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## fivecodys (Dec 2, 2013)

> I am surprised there are so many complaints about DC noise. I have a Jet pleated filter on a 2 hp machine. The exhaust stays in the shop because of heat loss. I do not have a cyclone. The decibel level of the machine running is about 70-71 db, the level of normal conversation. I am in a small shop and the sound doesn t bother me. Why are some systems so loud?
> 
> - ibewjon


I'm sorry I took so long to address your comment. Got busy and just forgot.
The noise in the shop was not the issue. It was the external noise of the air flowing through the 6" pipe and out of the dryer vent that was the issue. It sounded like a jet engine running if you were standing outside in the front yard. I believe this was inadvertently caused by the "Exhaust System" I designed. The sound was resonating like straight pipes on a motorcycle. We keep our front door open when the weather is nice and my wife said it was really loud and could be heard clearly in the house. After I switched over to the insulated flex duct work the sound was much softer and more like the volume of our dryer running. (Both are in the garage/shop). Someone walking by wont even notice it now.

I hope that clears up the confusion.
Have a great day!


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## ibewjon (Oct 2, 2010)

Understood.


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