Diesel heater silencers again but with dB levels as requested

[@MastaSquidge]

The only problem I have with this whole video is the generic, though very technically true statement that 3dB is a "doubling of audio" and that its "4-5 times quieter". From a human perspective this is misleading. I know this was stated in the previous video, but wasn't mentioned here. So I hope this doesn't come off as pedantic of snarky but I wanted to make sure it was here as well. While this 3dB statement is true in terms or actual energy present, that is not true of "loudness". 10dB less or more is largely considered to be half or double the perceived loudness, respectively. Again, he pointed this out in a previous video. 3dB is a very small subjective decrease while 10+ is very significant, as achieved with the generator muffler. This is why there's a lot of debate between the different "stock" mufflers. They are all so close that some people can't even tell a difference. Especially with background noise present.

[@DavidMcLuckie]

I have pinned this in the hope people will read it. Going forward I think I'll stick to the 10dB = doubling of actual perceived loudness.

[@bigoldgrizzly]

I agree pretty much with what you have said regarding the three decibel 'rule' as far as 'perception of loudness' goes, but would point out that this rule is of prime importance in noise induced hearing loss since damage to our hearing is directly related to sound energy levels experienced [and duration of exposure]. While this only becomes really important at noise levels significantly higher than these little diesel heaters produce, I still feel that this is something we should always keep in mind.

[@offgridcabinbelgium]

This was very educational. My wife snores quite a bit. I'm going to experiment with what I learned now.

[@eby6114]

Lol the birds were louder than the exhaust. Well done

[@scorned230]

I was thinking the same thing. lol

[@DavidMcLuckie]

At least they weren't stomping on the roof today, it was too hot.

[@jaybee258jb]

Just love it. Traditional hobbies. Who needs a TV. Thanks for going to the trouble of producing videos and sharing

[@craigsmithx]

Outstanding work, extremely clear process.

[@MrKb1959]

Clever fella and I love your presentation, really entertaining. Keep up the good work.

[@sprinterlex2082]

I do like the orange overalls. It always catches my eye on a youtube search and I find myself spending at least a half day watching your videos after I click on one of your videos. Those orange overalls are like a fishing line hook that pulls you in haha.

[@MyScallan]

Great stuff. Appreciate the effort in you making these.

[@artursmihelsons415]

More scientific approach! I love it! 👍 Thanks for effort!

[@thefirstmissinglink]

8:15 sounded best over my headphones. Agree about scrubbing the different frequencies.

[@TOMAS-lh4er]

DAVID !!!!!!! I was wondering where you were !!HI from ARIZONA , USA ! I have watched the heater saga from the first video you did with one ,, The longest-lasting test in Europe !!

[@preachers4135]

Excellent! Thank you David.

[@ianharvey868]

Thanks for this video, I was hoping the scooter then generator but the same idea happened with the webasto and generator exhaust. The large tin and the shape is resonant to the high pitch "whistle" direct from the exhaust line.. As I suggested in my comment on previous video it acted like a high pass filter then a low pass filter, whoop whoop

[@charleshamel2797]

My theory why big->small is louder than small->big: when high frequencies enter the big muffler, they couple or resonate with its thin large surface. I suspect the high pitch noise comes out of the surface of the big muffler, not from its output. The small muffler is more rigid and does its job better with high pitch noise.

[@gregriley649]

Thank you for sharing your knowledge 👍

[@burnarb]

hi David I have a diesel heater in my old camper and started to try and quieten it down a bit. but I found it was not so much the db volume but the pitch which annoyed me. After a homemade muffler got most of the noise there was an ear-rush noise which traveled quite a distance and the air intake noise was the problem so I baffled that. then after running it for a few weeks, I started to worry what all the restrictions may be doing to the heater so removed them all and refitted all the standard/supplied ones. Once I am in the camper I don't hear it It is all the people outside I am concerned about

[@DavidMcLuckie]

That's another good reason to quieten them. I've had comments like "who cares how loud it is outside?". I imagine the people camping in tents at campsites that the van might be parked in would like the heater to be quieter.

[@MiniLuv-1984]

Love this "home science" stuff. Its interesting how the closer the outlet to the phone, the louder it becomes...perhaps you can do the tests (again) with the microphone of the phone at the same distance from the outlet? I can already feel the heat...I'm let myself out :)

[@DavidMcLuckie]

The camera and the phone were equidistant on seperate tripods.

[@cambridgemart2075]

@@DavidMcLuckie The microphone needs to be equidistant from the outlet, i.e. moved back as the stack becomes longer.

[@easymac79]

11:57 I think it's EXACTLY what you said - the higher frequency is filtered out of the smaller housing then the lower frequencies in the larger. IDK the sciency bits, but I reckon it's something with the wavelength and resonance of the cavity.

[@RCModelling4U]

I left a comment on the original video. This experiment kind of supports my theory. Allow the gases to expand and slow down, and then exit through a hole larger than the input. This reduces the air pressure and reduces the venturi effect, which is what makes the noise. Using a same/smaller exit than input is creating a compressed air jet engine, thus more noise. On the decibel scale, the level increase of 10 means that a sound is actually 10 times more intense, or powerful.

[@bigoldgrizzly]

Perception is indeed very important. MastaSquidge explains this very well. 'Noise' is really just unwanted sound waves you find irritating ... and that is different for each of us. Asking me to judge which silencer is 'quietest' would not be very representative, as I have 60% hearing loss [worst in the mid frequency range] as a result of years of very close exposure operating the pneumatic rock drills in tunnels. I agree with your comment regarding venturi effects at the exhaust vent and also wonder whether some kind of axial vanes set within a section of pipe added to follow on from the silencer outlet, could perhaps channel the gas into a more laminar, rather than turbulent, flow at the exit. While I can put up with loud noises which would irritate or even 'enrage' others, the main drivers for noise reduction are to cater for, not just what irritates [or damages] ourselves, but importantly, the perception of noise as experienced by our neighbours.

[@MCBatty80]

I wonder how much pressure they are building behind them? do the 3 cheap ones have more pressure build than the others?

[@NoMissOutdoors]

Good experiment Mate... Cheers from Mississippi!

[@easymac79]

3:30 looks like bringing the point of outlet closer to the meter may be affecting it? lots left in the video, let's see.

[@alacosta5265]

i imagine the exhaust pipe is 1 inch from start to finish. would a 2 inch exhaust pipe make a difference since the air wont be so much under pressure throughout?

[@petertrevethick9814]

Would be great to see how the 'upgraded' silencers now being sold perform.

[@DavidMcLuckie]

I've ordered a new version and it is en route.

[@petertrevethick9814]

@@DavidMcLuckie Will watch for results. Since came across video John Mck - Chinese Diesel Air Heaters - Part 8 - Exhaust and Mufflers. He seems to think bends in baffle muffler might reduce airflow and, with total bends limit of 270 degrees, would reduce allowable bending elswhere in exhaust. Measured noise was worse with pressed baffle muffler, than with cheap pressed through muffler.

[@jregamey]

I had a Nissan Altima. It had exhaust drone. There's math to this design. But what I did is found the frequency the drone was in at what RPM. That determined the size and length of the pipe. Off the main exhaust pipe I welded on a other pipe with y fitting and made it about 3 feet 1 1/4 and capped the end. What this did was bounce back the drone sound canceling the original drone. It worked I was shocked

[@DavidMcLuckie]

Is that a resonance chamber? Is that the term. Good job though!

[@jaybee258jb]

Very very clever. Thank you

[@mannyfragoza9652]

what is the inner dimension of the copper pieces you added? Just an aside ive noticed when ive look to buy an Silencer the inner Dimensions are .022 that is the same size of my exhaust so i know it wont fit unless like you add some kind of coupling. Good video

[@888johnmac]

wearing the TM ovies in 30+ degrees , the mark of a pro ... BTW the webasto then the Genny silencer , did the webasto slow down the exhaust gasses , allowing the noise to diffuse more in the Genny silencer ??

[@MrRatkilr]

The Webasto must have thicker skin to it? The larger one may have thinner metal... less dampening effect?

[@raczyk]

whats the inner and outer piper diamater on the small muffler the diesel heaters come with?

[@royalspin]

On a total different note I've learned not to have any of my cats sitting on my lap when I watch your videos. It's that "" hello"" at the start that gets them . Not sure why but they freak out and bolt from my lap . Just thought I'd share.. LoL 😹

[@DavidMcLuckie]

It gives me great pleasure knowing I have the ability to do this to cats remotely and not just in person.

[@royalspin]

@@DavidMcLuckie Lol 😂 well after watching several of your videos they're finally getting used to you .

[@bigoldgrizzly]

@@DavidMcLuckie Your accent rather reminds me of Fife Robertson in the 1960s. Are you perhaps from the proud Kingdom of Fife ??

[@jorgechoypernia]

Thanks for this video. Would you be able to provide the link of the different silencers? Or the model so I can search it in Amazon perhaps?. Thanks

[@bigoldgrizzly]

I have always wondered what effect would be if, immediately after the exhaust leaves the heater, a transition piece opened the diameter up to say 2" and the remainder of the exhaust was made at this larger diameter in smooth walled pipe. I suspect that a lot of the noise is generated by high velocity turbulent flow of the exhaust gasses, particularly the most annoying higher frequency components. The above change in diameter gives a fourfold increase in cross section and correspondingly, the gas speed would reduce to a quarter of that in a 1" pipe. Advantages I can see are that the reduced back pressure would allow longer exhaust systems without reducing the total gas throughput of the heater and it would open up the possibility to use easier to find car silencers . So, quieter with no loss of efficiency ..... maybe worth a try ??

[@michealgillman7418]

Big is best...thanks David, I have the standard one on my 5kw...may try to fit the big un, or a guanine wabasto? Regards Mick

[@twocvbloke]

I'd still say the generator one was the best, the decibels measure sound pressure, but you can get high dBs from sound waves we can't hear, but get driven bananas by sounds which we can hear even if they're in low-ish dBs, so perception of sounds as well as their dB is important... :)

[@DavidMcLuckie]

That's the reason I made the first version without the dB. As we saw various combinations had very similar dB readings but sounded totally different. As long as it helps someone I'll add in a much data as I can. :)

[@MastaSquidge]

While this doesn't factor in the purely subjective annoyance factor of various frequencies to individuals, discarding non-audible noise is actually the purpose of dBA readings. The A-weighted scale avoids this issue of measuring SPL we can't hear. It also accounts for (some of) the differences in the loudness we perceive certain frequencies. As you can see on the screen overlay this is a dBA measurement. Regardless of accuracy of the reading, the weighting will still be in effect and will be ignoring those inaudible frequencies. So whether intentionally or otherwise he at least resolved the stated issue of SPL outside of human hearing. There is an improved weighting scale that can be used but I don't have the means to do so (yet) and I doubt he does either - however there's very little basis of comparison for people who are used to reading dBA figures on spec sheets for equipment.

[@mhicks80]

Would a flexi exhaust coupling between the heater and the external connection reduce any vibration transfer into the silencer? I agree webasto first and bigger silencer afterwards, perhaps a larger tailpipe on the big silencer would help the exiting gasses dissipate even quieter? Purely guesswork though, love these vids, keep up the great work

[@BigBoy4005]

I would call the Webasto or the clones a 'resonator' designed for the precise pressure pulses (volume of gas, frequency range) expected of the combustion process + fan. This effectively cancels sound energy against itself by setting up standing waves. The generator muffler, by contrast, just breaks up and delays while expanding the sound waves (turns a POP into a a phhopp). It really sounds like the body of the big muffler 'rings' with the frequency of noise generated by the heater; there is probably little apparent sound from the output itself.

[@thisnthat3530]

Yep, my thoughts were the generator muffler was leaking the sound through its casing too.

[@raczyk]

Do you have a link to the large muffler you've used?

[@koningbolo4700]

Is there any reason to not use a moped muffler ? Could such a muffler possibly causing a restriction in the exhaust line or cause other issues you have seen or can imagine please ?? I have a 2kW chinesium diesel heater and just today got a Puch Maxi exhaust muffler to test out.

[@DavidMcLuckie]

Assuming you retune the heater to match the exhaust it won't matter what you put on it.

[@koningbolo4700]

@@DavidMcLuckie I know how to tune a piano but I assume tuning a heater to match an exhaust is a different kettle of fish... would you care to explain how this is done please ?

[@fred51150]

tanks a lot for your vert usefull test on chinese diesel heaters

[@safenarrowboat6817]

Hi good vid where can i get a big muffler, from with no drain holes ?

[@deaniepops1]

Is it safe to put the silencer at the begining of the diesel heater exhaust so you have the rest of the pipe at the end.

[@DavidMcLuckie]

If you can make it fit yes.

[@haydenharris3059]

Sorry to sound so thick but does the unit still sound noisy inside and how many DB if possible.

[@DavidMcLuckie]

Do you mean with the exhaust vented outside how loud it is inside?

[@haydenharris3059]

@@DavidMcLuckie yes please 🙏

[@BritishWaterwaysSounds]

David, love the videos, might i make a suggestion for a video? i would love to see your efforts in trying to make a generator less noisy using this same setup IE Genny inside and exhaust through wall. Cheers and keep up the good work.

[@peterjohnson2245]

one thing to consider with dB readings is you need to use different 'filters or Weighting' dBA or dBC not just 'dB'. dBA is more for 'comfort' level of noise where as dBC is peak level, you can 'put up' with more base but get so will be exposed to it for longer periods before you 'suffer' loud noise fatigue or damage (how long before the low drum of the diesel engine on the night boat pisses you off) that is dBA where as dBC is more about peak levels eg chain saw or feed back from a mic. the thing is we can 'put up' with levels more at lower frequencies for longer thus more hearing damage. so you should test exhausts at dBA filtering

[@DavidMcLuckie]

Good news then. The Bosch app reads A weighted. If you look closely in the video you can just about see the dB(A) in the screen.

[@TheOceanX]

This explains why my jeep was loud when I got it and doesn't bother me now. Can the hearing I lost ever come back? :(

[@peterjohnson2245]

@@TheOceanX sadly not, once you have the damage... If you are as (un)lucky as me (sound engineer for live bands, theatre sound engineer, dj, being a drummer, using power tools you get the ringing (tinnitus) that stays with you forever...

[@TheOceanX]

@@peterjohnson2245 I am as unlucky as you. I’m 25 and former military, with a history of ear infections and issues. I’ve had tinnitus since my single digits. Sad to hear the loss can’t be reversed at all.

[@peterjohnson2245]

@@TheOceanX there unfortunately has been some who can't find a way to cope with tinnitus and actually exit life! I worry a lot about the future generations, all listen to music way to loud with ear buds. A lot only use one but don't realise how loud it is when compared to using 2.

[@Pugwash.]

A frequency analyzer might show you more details but the big-ass one looks sufficient. For the best result I guess you need to get one tuned to the frequency of the noise?

[@thomas1112002]

Any link for the scooter exhaust and am in Coatbridge Lanarkshire were abouts are you I have my Chinese night heater but not got round to fit it yet

[@DavidMcLuckie]

Scooter exhaust was just the cheapest one on eBay at the time. I'm about 20 minutes away, drop me an email if you need a hand at any point.

[@tonyrichards4141]

To my ears the webasto sounds best

[@easymac79]

8:18 experience going deaf. Holy crow.

[@beechFPV]

What is the big black exhaust ? I would like one

[@DavidMcLuckie]

It's a universal generator exhaust.

[@wayneturner7678]

where do find them silencers the big round one

[@DavidMcLuckie]

I just browsed eBay for various small silencers and generator silencers and made them fit.

[@LOFIGSD]

My neighbour wondered what my Diesel Heater was, told them it was a portable Heat Pump approved by the Government

[@scottl7644]

Dear David. Is that 22mm copper pipe??? Great video once again!!! ✌️✌️✌️

[@DavidMcLuckie]

I think so. It's the bigger of the two common sizes of copper pipe. I found a piece in the shed. :)

[@scottl7644]

Thanks David. Yea I can confirm it is 22mm copper pipe as I went out and just bought 1m to use with my heaters. Inside bore of exhaust is 22-22.5mm or there abouts. Thank you kindly. ✌️🙏✌️

[@David_11111]

link to big exhaust please :)

[@DavidMcLuckie]

Like this one, but the price is coming up now - www.ebay.co.uk/itm/303844323633?epid=19036407472&_trkparms=ispr%3D1&hash=item46be887131:g:YSMAAOSwcipf~WdA&amdata=enc%3AAQAGAAACoPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSzaVbXtmGxqmWnpn8RLN2qxUTJ1orsIztHpXfDVbbGLcc%252BR4ZJQ9gl3uT1r6CclO0iO4UIQDH4s8%252BtHXlgHaHNSXvh85r7Uz32qpJauzS3j%252F1m9aDjBUuTuj5ARO3M8MaETUEpv6HKxxP721JcDA3BkvAHMaiF808OT83vdLEksxBmdBg9Biw9zVxn9gZGMkgF0qni5yldQr4FRaWdeuzu8kdnOBFrvQyTczfUosakkM7rVpspWW51PojzB00QAlcVzMCeKPW2DRRr6cK%252FM0eOW9nCf7%252BbrW3oV%252BHaCAc43Gv1VGZhTozvSbI9AufHaeG23Er0b%252FAErHSxlwgZ5B87kga8R2pJSl8CxkJC4i5bTGgMjLS%252F2k296neQePZgZddUIUbZYsHLT43Q5Rc1G7gTCXOfq2bhg8Lcr7t6hDPWr6hpk153LaC%252BM2ihvUQfmZ84NHkPl1yzp16y%252FnbPRm5lgDUcRi8Vva40fanwCLpUeVFPsosXseiaxfdHxjGehG8%252Bsj4ma8YCD1CGkCuM0RU8QE%252B13KIBbRUkbf0M6yJ%252BTfxylFfrjT3c7cPkqYT1hLtE12Q97FNiZjB6LML0yma1wtgnfHDV421jFHFjvDoXgSRCpMoZR69HcVWPK8h0DvFkA8L17%252Fa94oLRrkwblCz66MAp5MmJPKoknXvmipfKseEF2lWuAN14FWBGg%252Flb3qG%252BM6K%252BIfzUpCMzyS4DK7lhOdMkR6efGfMa5UI2A6Bs6mcG9qSljVtxGV1e4dAdAmlKNOqpvU0GfJ0ZnU38ltt3X7rALkWK7QzhWmH%252B12qgj2UnM88RKTZY5RIYwwmBKyS9wXY5NHCKe9hMnZnFNfkeQ%253D%253D%7Campid%3APL_CLK%7Cclp%3A2334524

[@reubenk7331]

Honestly, with my exhaust outside, I really didn't care. It's barely anything in noise other than a wooosh noise. I put the silencer on because it was in the box, and put the exhaust further away from the vinyl siding though.

[@kurtzxcvb3481]

I don't know we haven't seen you without orange overalls LOL Shake That money-maker

[@mrsunelectronics544]

Gibt schon neue Modelle......D22 Webasto 1320910A ( alte Standard Model Web. 1320895A ) und Nachbau Versionen bei Ali China usw. Eberspächer Abgasschalldämpfer D24 mit Adapter auf D22...... (Heizluftschalldämpfer D60 1321735A ) gibt's auch Nachbau Versionen ☝️ gute Testreihe 👍 Grüße 🖐️ 😉

[@u.s.a.198]

Ty

[@kan815k]

Its not so much slincers. Noise also coming from the pipe itself. Try insulating the pipe then adding silencers.

[@brianferguson6278]

Hot exhaust gases through a metal muffler resting upon dry grass. Speed dial to fire department an idea?

[@DavidMcLuckie]

It's a long, long way from being able to set fire to that grass.

[@davidgates1122]

To put this in perspective . . . normal conversation is 60 dB. With any of the mufflers you are getting 3 dB or more reduction. So just use a muffler . . . any one of them.

[@michaelbockstaller5021]

Put a big stone plate on the big silencer against vibrations

[@sethwoot]

Put it thru an old water heater it would be silent..with a bit of work would heat water

[@gregs8672]

I might get a big muffler befor winter

[@David_11111]

yay

[@ChrisLesmerises]

1 Webasto 2 Webasto 3 Webasto 4.... All it takes is two Webasto's before diminishing results abhor. Now complete a 5 band eq for dampening XD

[@ChrisLesmerises]

PS. Subbed for your speedy turn around time on viewer requests, among other things.

[@kan815k]

Human ear picks up higher tones, but decibel meter picks up lower tones. Will never definitivt read.

[@allthesame3856]

Heeeellllooooooooo

[@MrBobWareham]

I think the scooter was best

[@craigdjbuller1844]

You were fighting noise distance. Basically the longer the exhaust the closer to your phones microphone..You were bringing the noise from exhaust closer to recording device. Resulting in a not as much of a dramatic decrease in decibels that was actually occurring. Its a good watch and I'm more informed before I purchase a heater. But would of been better moving the phone back 20cm if the exhaust was 25cm long. Each time you added 1 . 🤓✌ laters dude