marthavila: before we settled on the Fantech inline blower we were close to going with an external Abbaka unit which was the one that Modern-Aire had recommended for external use. It's quite low in profile and absolutely not what I'd call "huge." I've posted before about the choice of inline vs external blowers. Advantages of inline for us included easy install (as we have a full attic which was easily accessed), particularly as my contractor was reluctant to put his guys out on our rather steeply pitched roof. Similarly, any future repair would be easier. Also, some would argue that a fan in a protected attic may last longer than one mounted where it's exposed to sun, rain, snow, etc. External blowers however are probably the ultimate for noise considerations, and avoids the possibility of noise from the attic spilling into a bedroom underneath (not a problem with out layout). Here's a link to the Abbaka external blower: Abbaka Hyex 1.4 1400 cfm external blower Remember too, marthavila, that just because you use a different brand of blower doesn't mean you can't still use the Fantech silencer too, if you have the room for it. ya think: I agree that fan turbulence is a big contributor to overall noise: that's why, for example, my inline blower has an innate advantage as that fan turbulence is located in my attic instead of in my hood. Between moving the fan turbulence into the attic, and ditto for the actual motor noise, plus putting the silencer and 15' of duct between my hood and the noise source, the advantage is pretty substantial. No way an internal fan can come close, at least as it relates to noise.

The light assembly failed shortly after we got the hood the first time. It was replaced. It failed again in October (we had the hood a little over 3 years total). The tech asked if we cooked more on that side - he thought more heat there And why we weren’t having the issue on the other side. he also asked if we run the fan when we cook, which we do - since that would minimize grease getting into the assembly. it seems to me that a hood should be designed to deal with heat - it is over the cooktop. The fact that the light assembly doesn’t seal out grease if that impacts the functioning of the light or any other internal mechanism in the vent hood is a design problem. I fully expect the light assembly to continue to fail from normal use based on this experience and what the tech told me - since there is no way to clean the grease out of the light assembly and heat from using the cooktop is expected Changing light bulbs is not the issue. I am now concerned about what other mechanisms have been affected or will continue to be affected by the inability to withstand heat and grease that gets into places that you can’t clean The $380 to replace the light assembly includes $145 for the service tech to visit, $64 for the light assembly part and $149 for the installation which is removing 2 screws and reinstalling the electrical connectors and the taxes. I did contact wolf and they agreed to cover $164 of this cost and recommended that I stick with their authorized service provider. When Clarke came to my house the first time, they fixed it quickly for no charge. When they came this time it took over a month to get an appointment- they told me that it might get covered by wolf or I might have to pay for it. Despite having told clarke what the issue was when I called they did not have the part when they came to my house. I had to pay the service fee before he left (he was at my house less than 5 minutes which included going to the truck to look for the part) and they called back later to say the soonest they could come back with the part was another 5 weeks. I wish I had done better research before I selected the unit. I am very concerned about how long it will last Given how much it cost originally- I never expected to have these kind of issues and that the cost to fix them would be so exorbitant I now will do better research on what the best long term solution is I will say that the dual fuel range and the wall oven from wolf have had no issues and they work well - I had a wolf cook top and double oven in my previous home and loved them as well which is why we thought going with a wolf vent hood was a good idea

I am the resident expert only because real HVAC systems engineers don't frequent this forum, as far as I know. Noise introduced into the kitchen will be significantly reduced if an external blower with silencer can be fitted. A lot of the high frequency blade tip turbulence caused noise will be removed. This is also true of an in-line (duct mounted) blower. The issue of the neighbor is difficult to assess. What is the configuration of his or her windows relative to your potential external blower (1500 CFM I assume you meant). Your own window sound transmission is also an unknown. Generally, the external noise could be abated by (a) using a silencer on each side of a duct mounted in-line blower, or (b), using a deliberately under-driven* "up-blast" commercial blower (mounted as a side blast). (I think opaone is using an under-driven blower for his new system.) It is also possible to use a chase to move the blower up to roof level. I have a 1500 CFM nominal Wolf (Broan) blower on my roof. Its sound level is detectable but not obtrusive from the ground, but it might be if in a wall location where the sound is "trapped" between two houses. Possibly a more expensive but similar in design Abbaka downslope unit would be marginally quieter. ------ * commercial blowers of this type can use a pulley system between motor and fan that allows for different ratios. By choosing a ratio that operates the fan blades below their rated speed when the motor is receiving maximum voltage, significant turbulence noise can be avoided. The physical cost is a larger unit than would otherwise be required for the desired flow rate. Residential blower fans are directly coupled to their motors.

I may have failed to notice catinthehat's response of April17, 2018 because I don't see a response from me. Thanks for the link. Ria Raj: The fan curves by duct length can be converted, but either way don't tell the critical part of the story -- what is the pressure loss vs. flow rate of the hood with baffles in place? This pressure loss may be expected to dominate duct loss when using 10-inch ducts at the 1400 CFM blower's full power, even a 100-feet's worth. And that assumes no MUA pressure loss, which will certainly exist, even with a sophisticated active MUA blower system. I still recommend assuming a 2/3 of rated actual flow rate when all of the variables are not known, and using that value divided by the hood entry aperture area to achieve roughly 90 CFM/sq. ft. My asserted hood rule is: Overlap the cooking plumes to achieve good capture, get the velocity in the baffle gaps up to roughly the highest plume velocity, ca. 180 ft/min. (With induction one might squeak by with a bit less due to lack of a gas flame aiding the upward velocity of the plume.)