amd, Although I have heard the term sones used many times here on GW, I am not sure how to equate it to decibles or actual noise levels. I suspect your main source of noise problems is with an internal blower. While there have been many good discussions on GW on the merits (and quietness) of properly installed vent hoods with internal blowers, having had both internally and remotely mounted systems, I have to conclude that the remote systems are quieter by a huge margin (HUGE!). I have also heard reports from those who have them, and it makes perfect sense to me, that in-line systems can be just as quiet as remote (feature for feature). Although this has no real relevance to your problem, I have always thought the name "Hurricane" for a vent hood model was a poor marketing choice. I know the analogy is tremendous wind speed but for those of us who have been through many actual hurricanes, we associate hurricanes with "LOUD" as much or more than wind speed.

As previously noted in many past threads, one can have at best two of the three characteristics: performance, aesthetics, and "not overly pricey." One can also trade off among these for some balanced result. But in no case will a hood or hood insert suitable for a 48-inch range that will actually be used for cooking not be pricey by most observers' senses of valuation. One should be aware of not only the insert's and exhaust blower's costs, but also the necessity for make-up air (MUA). Supply of MUA in many or most cases requires some type of MUA system, with its own ducting, blower, control system, and perhaps filter. In this Appliance section of Houzz there are many hood threads developed over the past 10 years with information related to manufacturers, and more importantly for beginners, information related to requirements, particularly performance requirements, but also approaches to keeping down noise. Rather than repeat all these here with all the necessary background information, please take some time to search these out and review them. Then specific answers can be given without requiring an extensive level of commentary. This should also clarify the scope of information you will have to provide to refine the analysis.

@opaone Thanks for the reply . My recent google search says that there is a direct formula to convert sones to decibels . Maybe this will help some people: dB = 33.2×log10(Sones) + 28 But for those a little less math oriented, there are conversion tables online. Of course, this formula does not help to tell you how loud a range hood will be based on published information since the published information is garbage . But at least it will help people prove that their range hood manufacturer is a liar . I did exactly that with a previous range hood and got a refund . So here are my data: Range hood make and model: GE UVW9631 professionally installed. Duct is about 1.5 meters long , right angle, externally exhausted , a reducer from 8” to 6” was required Ambient: 35 dB Low: 51 dB Medium: 60 dB High: 64 dB Boost: 67 dB Ambient: 35dB This is the published noise rating from GE (cfm/sones): 100/1.0 (Working Speed) 290/2.5 (Medium Speed) 380/4.0 (High Speed) 610/- (Boost Speed) For reference, the actual noise level of 51dB on low fan speed is about 5 sones , compared to the advertised 1 sone, 28dB. Way off.

When moisture and grease particulate laden air flows through a duct, there is turbulence and these two components will be brought in contact with the duct wall. Slow moving air will allow condensation; fast moving air will allow impingement collection. In general, both likely happen at different ratios depending on temperature and fan setting. I wouldn't change a duct diameter just for this reason. What you have for a hood is unconventional. Commercial hoods and "pro" residential hoods use baffles that cause two 180-degree turns in the air flow. The larger grease particulates are deliberately impinged on the baffle surfaces, and given some baffle angle will drain toward a collection point. Even without angle, the grease is trapped where it can't easily drip down onto the cooktop. I don't know the details of this fan scheme, so I won't comment on what it might be doing with grease. When you initially wrote that you were having the hood installed, I didn't bother with commenting on its design -- sorry. Whether grease dripping from the fan grid was intended or not I cannot say, but it likely is consistent with the physics of the hood design. Again let me pontificate for this forum that the farther a residential hood deviates from long-time optimized commercial hood design, some portion of performance and efficiency will be lost. Running the fans for a minute before generating any greasy effluent might help with condensation, but I think the fan blades here are causing grease collection around the grill as well as wherever it is supposed to collect.