Fighting noise from the hood. Valve ejection. Backflow preventer.

We bought an exhaust hood with a 12/15 cm connection (manufacturer's reduction). Since the entire gravity ventilation system is made on a 10 cm galvanized pipe (20 cm riser), we connected the hood to the installation with a 12 cm spiro pipe and a 12> 10 cm reduction. run! There is little hum, but the hum is great from the hood area, and the 1st gear hood can be heard all over the apartment.

It turns out that on this installation 10cm there is a fire protection valve and a backflow preventer (brrr!), Plus 2 reductions (15> 12 and 12> 10cm), so probably that's why such problems. We are going to throw away these 2 m of galvanized pipe 10cm and change from the eaves to spiro 15 cm. But we have questions because we're doing a PhD in noise :

1. is it possible to throw away the fire protection valve (there is no gas), because it probably chokes a lot
2. Will the 15 cm pipe be OK, or can it give a wider rectangular cable, because the plasterboard is only 15 cm, so you can make, for example, 20x15cm, but is it worth it so wide?
3. Where should the swing-back flap be located and what kind to prevent it from "banging" in higher winds?
4. in this case, will a pipe with additional insulation help with noise? For example, spiro with insulation?
5. The connector next to the vertical is 10 cm anyway, so do all these actions make sense? Or maybe there is some way to professionally increase the spigot in the ventilation riser made of sheet metal (fi 20 cm) to a larger one?
6. The standard reduction of 15> 10 cm is very short! Would a longer and milder non-standard reduction definitely improve the situation?
7. Should the hood mount be better, eg on anti-vibroacoustic rubber pads, and can it provide anti-vibration tape between the hood side and the tiles in the kitchen?

What are your experiences? Many thanks for every attention of practitioners, because it is a matter of "life" for us - the annex and the great noise from the hood is a total failure!

Flat? Or your own home?

The description in the block has been supplemented

Hello
Unfortunately, I won't have good news because IMHO:
- fire valves (or fire damper) are installed on the border of fire zones. Their task is to prevent the spread of fire between different fire zones in the building and the presence or absence of gas does not change anything. It follows that it is absolutely impossible to throw it away.
- you cannot mix gravity ventilation with mechanical ventilation and you are planning something like that.
Now purely theoretically. If the noise comes from air velocity, each area that is enlarged causes a decrease in noise. It is assumed that about 5 m / s in ventilation ducts is still a decent air speed which does not cause excessive noise. Such noise can be (partly) damped by the use of insulated ventilation ducts. Of course, each narrowing of the duct's cross-section causes an increase in speed (read: increase in noise) If the noise comes from the motor (fan) itself, it may be a bigger problem to eliminate it, and additionally it is more likely that by limiting the revolutions, the engine will vibrate and the effect will be different than assumed . Please also read the parameters of the purchased device - it may turn out that the manufacturer assumes just such and not another sound level of the working device and then it's the end of the fun.
greetings
pm001

Thanks pm.001 !
In the apartment, the designer mainly opted for mechanical ventilation, also with fire protection valves and anemostatics. However, we have a common (5 floors) gravity installation for the eaves - I don't even know if it can be used in construction, but probably yes.

fire valve - it seems to us that he suppresses the most and we didn't have anything like that in the previous apartment in the block. Currently, it is tempting to take it out, because there is a lot of resistance, and you can't see it anyway
Volume in gear 1, the manufacturer states 28 dB, and on 3-m - 45 dB. Currently, it is definitely over 50, maybe even 60 dB, because after a few minutes you feel bad.
Performance the rated one is about 800 m3 / h but I do not know in which gear (there are 4).
In any case, a 10 cm cable with a speed of 5 m / s can only be pushed through about 140 m3 / h (!)

It already seems to me that manufacturers are outdoing each other in terms of parameters and noise in product cards, but this has nothing to do with the requirements - they do not write about them at all, or not much. Maybe the 25 cm diameter would meet your requirements (5m / s) but the riser itself is only 20 cm wide and 6 flats connected. I can already see that comparing the parameters of the hood and the riser, there is probably little room for improvement, right?

and what company do you have the hood?

Portfolio NC2-60
The product card says about 28 dB in 1st gear:
http://www.teka.com/html/pl/downloads/product/PR-0000156.pdf

Hello
IMHO in one building may have mechanical ventilation and gravity ventilation systems, but they certainly cannot function based on the same ventilation ducts (drafts).
The case of the fire protection valve (its presence or absence) results only from the guidelines of the fire expert adopted for the building at the time of design and included in the fire development scenario of the building. The fact that it is present in one building and that it was not in another is not an argument that would allow for self-removal of this element. Of course, it is not my question or anyone else on the forum to act as a guardian of the regulations, but let me remind you that ignorance of the regulations does not exempt you from applying them. So much for a formal issue.
The loudness stated by the manufacturer is nominally measured at a distance (this is usually 1m or 3m from the sound source). If in fact the sound level is exceeded that much, I suggest an experiment. Disconnecting the ejection from the common building installation. This experiment should allow to diagnose whether the source of excessive noise is the fan itself or, which is much more likely, the ventilation system.
Efficiency is usually given at maximum gear and additionally at a certain pressure on the fan. Here it may be that the 800m / h hood ventilates at zero pressure (no resistance to pumping). Let me also ask where you should replenish this air from? After ejecting 800m / h of air from the room, you must bring the same amount into the room.
Let us add to this the right suggestion describing the possibilities of installing the entire riser and the conclusion will not be optimistic because it is highly probable that the hood does not have the right conditions to work in the place where you install it (high resistance, wrong sections, no air replenishment). Unfortunately, trade is only interested in selling and leaves the user with problems. But that's a completely different story.

Thanks pm.001!
Mechanical ventilation and gravity ventilation are run separately and the windows are ventilated. It turns out that the fan the gravitational one is common for 6 apartments, and the mechanical one is separate but also common. And here I got the idea that because we live 2 floors in front of the building's roof, why not use the vertical space and place an individual collector there, e.g. fi 200? It all depends if there would really be a place there ... I am afraid that these 6 apartments will be bought by "strong" hoods and at peak times (lunch), there will be pushing - who is stronger? 6 hoods on the collector fi 200 is too much in my opinion!

When buying this hood, we looked at dB (very low, because 28!) And matching efficiency, because according to http://www.okapykuchenne.pl/shop,prod
for an annex with a room of approx. 28 m2 and h = 2.5 m, the demand is over 800 m3 / h. In addition, we thought that it was better to have "excess", because then 1st gear would be enough, the 3-year warranty was tempting and the 28 dB of noise was tempting, which, incidentally, turned into a headache, because it is impossible to work in the kitchen (I -run) neither to talk, nor to listen to the radio or TV -ot. a nightmare for which the producer does not want to take responsibility.

According to the above-mentioned page, a similar DG3 90 hood (the same performance and noise) has the actual noise measured by the seller:

Producer: I - 28 , II - 36, III- 45 dB
Company Measurement: I - 49 , II - 59, IV - 63 dB
http://www.okapykuchenne.pl/dg3_90-p94.html

hence it seems to me that the producers are just deceiving us !!!
I hope that someone who has dealt with a similar problem will answer, because I still hope, although it seems to me that without installation, this hood is quieter (we unfastened it), but again not so much that there would be a noise on 1- first gear (28 dB). So what the hell is the producer doing? Oh, he is just deceiving us, either by providing tempting operating parameters, or by understating, because maybe we should pull the installation of fi 200?
For now, thank you and invite others to share their insights and ideas on what is worth and not worth doing to reduce the noise.

From my little experience with hoods and noise it turns out that the main cause of this is transmitted to the environment vibrations and resonances.

You have not written or I have not noticed if the hood is noisy when it is not installed and not connected to the ventilation system. If it makes noise when it is not mounted, it means that it is either broken-defective and for complaint, or you have bought this type.

If the noisiness occurs after the machinery has been installed, the reasons are to be found in the installation and connection. Here you must take everything into account. Starting with what your walls in the kitchen are made of, because if they are made of plasterboard, then unfortunately no rubber bands or other patents may have a big effect. Check that the source of noise is not the decorative column or that the adjacent cabinets do not resonate with the machine.

Thanks kraf101
I was writing... Well, after disconnecting from the installation it is slightly quieter but it is not 28 dB at all. The company does not want to accept the return, as it stayed 1 month after the purchase however, I believe that they are bending, because in my opinion the goods do not comply with the product card.

I have to measure it somehow, it is possible that I will use the website. finally, a 3-year warranty.
I am also thinking about vibroacoustic actions, I am thinking about mounting it on the wall on an anti-acoustic mat, using flexible cables, etc. Greetings!

minimaxi wrote:

Thanks kraf101
I was writing... Well, after disconnecting from the installation it is slightly quieter but it is not 28 dB at all. The company does not want to accept the return, as it stayed 1 month after the purchase however, I believe that they are bending, because in my opinion the goods do not comply with the product card.

But are you talking about detaching from the installation or removing from the wall?
In my opinion, you should disassemble the entire hood, put it on a carpet or on a bed and then check what noise it makes. If in such conditions it will significantly exceed the declared value, you have a few paragraphs in the Civil Code to force the seller to replace or return the cash register.

If it is quiet, you have to think about it, because the reason lies in the assembly and, unfortunately, it is not certain if it can be eliminated.
I would do it something like this:
- Install the hood by itself without a pipe, using microporous rubber or something. If possible, try to avoid touching adjacent cabinets. Then connect the pipe and finally attach the blende.

Check the noisiness after each activity, then you should get an answer as to where the dog is buried

this is exactly what is called non-compliance of the goods with the contract and you can safely advertise it, but no later than 2 months from the discovery of this non-compliance. You will surely need an expert opinion. It is hard for me to believe these 28 dB even in 1st gear

6969lysy but you see .. I gave access to the product sheet, and I asked the guy who deals with work ergonomics - he said that 30-33 dB is a normal noise of office equipment when there is complete silence
The portfolio is bending and I will not leave it like this, if they do not want to agree to the return, the anti-advertising is ready!

The formal opinion of the expert is the money and then the court ... who wants? TEKA gives unrealistic parameters and should pay for it ex officio!
Does anyone know how reporting this case to UOKiK will work? Does this put a heavy burden on the customer?

I'm back with the topic as it's time to rework
I have specific questions for experts about the selection of a good 150 or 200 cable and anti-vibration material to be placed on the wall to attach the hood.
The eaves socket is fi150, does it make sense to give a reverse reduction of 150/200 and pull a cable approx. 2 m fi 200? B. I am asking for advice on what pipe to use, with or without insulation?

Hello.
I will join the topic and tell you how I dealt with the noise (air noise) of the hood.
1. I wrapped the pipe under the hood casing with felt (as much as possible) because there it was the most noise, because there I used a reducer and it always hums there.
2. I bought a lighting regulator for a lamp for about PLN 15 and soldered it, limiting the speed in 1 gear.
It's super quiet.
Greetings.

carland -unbelievable! Hood in a hat?