Sounds like you need to cook for your neighbor every once in a while. :) How far from the property line is your exhaust point? putting the blower in the attic, even if it's on the same side of your house might help since the wall will help with sound isolation. Also, in the attic, you can put up further sound isolation between the blower and your neighbor in the form of foam or other materials that absorb sound. Get yourself an SPL meter. They use to have analog SPL meters at Radio Shack for about $50. Turn your fan on full blast and check the level at the property line. You might be able to achieve a compliant sound level with some vibration dampers (rubber gaskets/washers between the wall and blower) or a sound barrier around the existing blower. This all depends on what frequency the offending sound is at and whether it's motor noise or air movement noise. If it's motor vibration noise, it could be causing your walls to resonate the sound and direct it all towards your neighbor. Rubber standoffs might help to stop that and certainly attic mount even if it's just inside the attic might help.

One idea is try finding the largest disposable styrofoam ice chest you can. Hopefully, it will be big enough to surround the wall mounted blower. Then cut out or punch holes on the side where the blower blows. See if there's any significant drop in sound level.

If money is no object, then find the blower with the biggest duct diameter you can but does *not* have a super high cfm rating. Larger blowers/fans can move the same mount of air with less velocity which means quieter. That means a 600cfm blower made to fit 8 or 10" ducts might be quieter than a 450cfm blower made for 6" ducts. This is actually why running a 1200cfm blower at half speed is usually quieter than average 600cfm blowers at full speed. It does however, require you to replace your ducts in order to have the best results.

Good luck.

I can't tell you what a reading would be off of ours, but we have a Best by Broan hood with their external blower. We have a 10" duct, 90 degree turn and a 45 degree turn, total run of about 15-16 feet, I think. The blower is right above our kitchen window, and I wondered if that was going to be a problem. I don't hear the blower -- just the air moving through the hood. I just turned it on full speed (1200 cfms) and went outside and stood right under it on our driveway. It sounds like a box fan or floor fan -- you hear it moving air but I don't consider it loud. At about 3/4 position on the slide control you would hardly notice it, and except when cooking really smelly things, we usually have it at half or less.

amcook,
Thanks for your ideas..
We are in the city limit. Our set backs are 5 ft from the property line which means only 10 ft from the neighbor's house. We have our kitchen on the second floor for view. So our kitchen is at the level of their bedroom which creates more problem!

Unfortunately, I do not have attic space because I chose to go out, not up, due to esthetics... Even if we did, we have low roof line and the space is darn small there. We may go into the soffit, turn and travel in the attic crawl space and punch out through the roof. (Can we say expensive!)

I think I need to look at other brands of external fans. I am not happy that Fantech was not able to give us sound rating. We asked before we bought it and they just said NOT LOUD! Egad, it is very loud. I am hearing alot of motor noise in addition to air noise.

I will also check out Best by Broan's fans and see if they have sound rating.

Thanks

kais
Sorry to hear about your noise issues -

Hmmm - Since hoods are utilized on high speed typically for only very short bursts I find this curious. I assume your neighbor complained? Do you have a good relationship w/your neighbor (besides this issue)?

Does your neighbor ever use a shop vac, leaf blower, saw,music, dogs,how about cars?

If the town/city can enforce this on you, then they must do so for the neighbor & all for that matter. This is why many towns do not have a noise ordinance - difficulty enforcing

Do you have a copy of the full ordinance? Many would have hours that the noises are acceptable i.e. between 7A-9P. IF not I would definitely obtain a copy - otherwise you will be chasing good money after bad.

Good luck!

Here is a link that might be useful: example of NJ noise ordinance

YOu need to islolate where the sound is being produced rather than start planning on replacing what's there already or else you may end up with the same problem all over again with more money down the drain. If it's vibration, that can be cured. If it's motor noise, then perhaps it's defective, as the motor itself shouldn't be that noisy. If it's the noise of the actual moving air, then, there's very little that can be done about it other than to change the point of exhaust. However, that's the least likely scenario.

You need to do a LOT more research on your existing installation first. In "noise" complaints, it's more common that the install is an issue rather than the product.

jejvtr,
There is a maximum allowed noise from equipment. On page 6 of NJ noise ordinance, there is maximum allowed noise level at the property line. 65dB during the day and 50 dB at night for NJ. My fan exceeds noise level well above that which was measured with the noise enforcement officer.... We were told that it was 55dB in Seattle. Either way, the fan is VERY loud. My husband uses it first thing in the morning to boil the water to make coffee. We do not use a coffee maker. My DH is rather neurotic when it comes to using gas burners without the fan on. He thinks the fan should be on no matter what as long as there is burning gas from the oven/cooktop.

I talked him into NOT using the fan first thing in the morning.

live wire oak,
I think it is the motor noise. The motor sounds very loud at the high level. It is really not an acceptable level of noise even for the interior of the house. We tried to have the fan company give us sound spec and they were unable to do so. Perhaps, we should push them more to give us the spec. When we measured it at the source, it was near 80 dB at max value. This is very high!

If the scenario was reveresed, I would not want my neighbor to have such a loud machine outside of his house.

I may decouple the fan and turn it on at full and measure the sound of the motor noise and see what it is without the air moving. You are right in that if it is the moving air, then there is not much we can do about it.

Could you build a "surround" for it on the exterior of the house? Kind of a house outside a house? Maybe it's something could be done that would dull the noise for the neighbors.