Reducing Noise from an Oil-Fired Furnace

I visited a cogen installation one time, and they had about six large diesel gensets paralleled with the utility company making about 10 megawatts.
Their manufacturing plant was located adjacent to the generating building, and so they needed a quite installation.
One entire wall of the generator building consisted of air intake louvers, and to prevent noise from getting through the louvers, they had a second wall outside the first, with baffles between the walls.

Although the space between the baffles was large, perhaps 24", the baffles were designed for the genset noise frequency, and they somehow bounced the noise back onto itself, and canceled perhaps 95% of the noise.
It was quite remarkable to be standing near the gensets, and be able to see them clearly through the baffles, but almost not be able to hear them when running.
Inside the building with the gensets running (without ear protection) was deafening.

So with acoustics (which I don't know much about), I think it is a matter of identifying the objectionable frequency(s), and then figuring out how to cancel or re-direct that sound energy (easier said than done).

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I seen where put in pit to reduce the sound .
The other is to concrete blocks 8 x 8 x 16 after stacking fill center with sand or dirt
It can be move later too.

Dave

 

One thing in our favor when dealing with furnace noise is that the noise source is small and well defined. Compared to, say, a sawmill or fabrication shop, our noise sources are very compact. That compactness allows us to deal with them as a point source so that expensive solutions like berms, walls, or full-on work area enclosures should not usually be needed. And that is why I elected to work on containing the sound within the furnace itself as that is by far the most economical approach concerning both time and money. Ancillary sources of noise like the blower and compressor are also small point sources of sound. In my case, the choice for blower itself is relatively quiet and I am presently 90% finished enclosing it in a box to make it even quieter. The compressor, a 50-year-old Quincy knockoff is contained in a barn already and does not generate much noise in the outdoor area of concern. (I am lucky there.) However, I started out using a pancake compressor which provided adequate air but was very loud and, by its very nature, very annoying even though it was one of the better portable compressors with respect to noise.

The concept of low frequency noise transmission from furnaces like we use is interesting. I am having a hard time knowing how that could be assessed and validated as a potential source of noise.

Denis

 

I ran my furnace tonight, and I put rubber pads under each of the three wheels.
These are the rubber walk pads that can be bought in a variety of stores, and are about 1/2" thick.

The pads broke the ground coupling to the furnace, and the low frequency rumbling was noticeable reduced.
I asked my wife about it when she was entering the front of the house, and she also said it was noticeably quieter.

It still makes noise, but you don't feel it through the ground anymore, so some progress made.

 

Would it be possible to measure noise levels with a smart phone app? Holding it in the air and then placing it on the floor would be interesting as some of the apps do analyze frequency data.

Denis

 

Just be sure to cut the SOB off the christmas card list. Some people just live to put there noses where it doesn't belong.

They now recognize the noise is a furnace because you told them. Now it's not "unfamiliar" Problem solved.

 

I apprectiate my annoying neighbor who doesn't appear to own a vehicle with a muffler and who likes to have burnout competitions with his buddies on the road a lot more, thanks.

It's harder considering the property is not yours. I try to be accomodating to my neighbors, but there comes a point when you have to tell them to go fly a kite. It's hard dealing with an overly sensitive neighbor with unrealistic expectations and a pissed off neighbor can make for many unpleasant days so it's usually best to try to find a peaceful solution, but sometimes nothing less than a firm insistance that they go f*#k themselves with a bit of rusty barbed wire will suffice. Hopefully they will commit said fornication quietly as they appear to feel you shouldn't ever hear one another. Perhaps some extra bushes along the property line will help long-term? Anything that breaks line of sight usually helps, not so much with just the noise reduction but with the nosey-ness as I suspect seeing activity draws their attention to the noise as much as the noise itself.

Too bad you aren't my neighbor, I'd glady trade you for random gunshots, atvs/motorbikes, drunken howling, and the aforementioned burnout competeitions on the road. They're annoying, but we live in the country and there's a certain level of mind-your-own-business that goes along with that. We don't socialize and they keep the stupid over there, so I stay over here.

 

Wind plays a huge factor when it comes to sound. If it's blowing their way, they would probably complain if you blew them a little kiss out the south end of your own tailpipe!
You do know raising chickens is a really stinky method to piss off the neighbors. Even spreading some chicken crap on the veggies should be enough to let them know you are thinking about them.

 

I suppose that would be possible for someone who was smart enough to operate a phone app, unfortunately that rules me out, I have never used one.

I may look for a cheap (if that is possible) db meter.
I would like to check it while they have the expressway behind my house down, since they are suppose to build concrete sound walls if the level is above X percent (not sure the value).

I live an app-free life.
I guess that is good.

Edit:
I do use my phone calculator, clock, and calendar, so I guess in reality I am somewhat guilty of using them.

Edit02:
I purchased an inexpensive dB meter. It should be here in a few days.
I will take some readings in the air and on the ground, with and without the foam pads under the wheels.
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You might drop a hint in conversation that if you can't melt metal "occasionally", your other passion would be raising a couple of pigs, as pets but paying their own way in bacon etc of course. However, you're contemplating whether they too might be randomly noisy and a bit 100% smelly especially in summer..... but on the other hand the manure would be good for the new boundary hedge, so that they couldn't see the pigs, unless they would be happy with a pig sty view?!

 

Your vehicle would make a movable sound blocker if you can park it between the furnace and house.

 

The readings you get with your meter should be interesting. Numbers add a lot to understanding. (Apps can be confusing ;-) )

Funny you should mention farming. The land covenants specifically allow unrestricted agricultural use. When they were signed a failed attempt to prohibit pig farming was made. My friend I consider that our ace in the hole! ;-)

Denis

 

Maybe we are approaching this all wrong, with the right exhaust geometry you'll have a valveless pulse jet motor:

 

+1.
You must live in my neighborhood. I found out at 9am Christmas morning last year that Santa brought the neighbor kid a new 12ga.!
Ooh! Pig farming? Rats and pigs go together like peas and carrots!

Pete

 

I agree with getting along with neighbors. The line of sight may be the biggest problem. If they couldn't see you they probably couldn't hear you. 180 ft is a long way for only 73 db. What do you measure close to the furnace? Does it require (or should you be using) ear protection? I'm surprised how quiet my drip burner is, all my noise is from the leaf blower. Why is yours so loud? Is it louder than a typi

 

This type of burner works great
I use one on 40 pound furnace for both aluminum and brass back be for 2004
It work with flip of switch at 242,000 but

Dave



https://m.grainger.com/mobile/produ.../Grainger/3AAC2_AS01?$smthumb$webparentimage$

https://m.grainger.com/mobile/product/DELAVAN-Nozzle-3AAG3?breadcrumbCatId=19249&fc=MWP2IDP2PCP

 

You can find oil burner use at lot lower price and some time free.

Look around for price I purchased one from Grainer back in 1990's due high cost of LP

Dave

https://www.supplyhouse.com/Beckett...ping&msclkid=9d26e1560bda1ec40397ba812a6846a9

 

I'm wondering if a tuned pipe like a two stroke bike would help: they work by reflecting pressure pulses while allowing gas flow to exit. If I had the material to spare, I'd make a vertical one with a sliding reflector to tune it to the furnace sound. So it may be possible to tune it for sound reduction rather than exhaust scavenging.
https://upload.wikimedia.org/wikipedia/commons/5/52/Arbeitsweise_Zweitakt.gif

Edit: I suspect the correct tuned length would be pretty long, although the speed of sound in a gas is dependent on the temperature of the gas so tuning may not be practical for all temps. Higher temps increase the speed of sound and also the tuned length which would be a half wavelength of the rumble frequency to cancel it.

 

My biggest concern is putting something (anything) in the exhaust stream.
The flame temperature coming out the lid could be up to 3,820F, and that is not quite as bad as what comes out a cutting torch tip, but nearly as bad over an hour or more period.

Even if the flame temperature is only 3,000 F, that is very hard on most materials.
The exhaust stream easily melts steel in just minutes.

I am thinking a double walled exhaust pipe with a leaf blower delivering air between the two pipes.
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