Replies

1. 
   Alan_Kim | Jan 06, 2002 03:43am | #1

   *
   Just curious - where is the makeup air coming from ?
   Do you have any gas fired devices in the basement or a fireplace nearby ?

1. 
   Tim_Rice | Jan 07, 2002 04:37pm | #2

   *It would be feasible to add an inline booster fan. How big is the ductwork? How much static is no the fan?

1. 
   Jeff_Maras | Jan 12, 2002 02:45am | #3

   *I don't know if the inline fans are rated for grease. This would be worth a call or E-mail to the manufacturer. Fantech is one company. Let us know if you find out anything. I've thought about doing away with the screamer above our stove and putting an inline in myself.

1. 
   David_Thomas | Jan 12, 2002 03:47am | #4

   *Cook: You are right to factor in the turns in a duct run as they can create more pressure drop than the straight-run portions. Note than doing an offset with two 45's is only half the pressure drop of two 90's. Doing it in two 22.5's would be half again.Reducers can be even worse. Never use the ones with 90 degree angles. You want a smooth and gradual taper. Better yet, use one duct size throughout. And make it at least what the blower outlet size is and of as smooth a material as possible. Plastic (check if it is allowed) is smoother than rigid metal which is itself much smoother than flex metal or insulated, flexible metalized cloth. If you are pushing the limits, use no flex anywhere. Get a pair of tin snips, some band-aids, and that sticky, aluminium tape sold for this purpose (NOT "duct tape"). -David

1. 
   cook | Jan 15, 2002 07:18pm | #5

   *David Thomas,Great advice on using the 22.5's and 45's. I think I can do that pretty easily.I have been able to find inline fans designed specifically for range hoods, so I assume they are rated to handle whatever would typically get that far. The hood itself has a grease screen, so that is not my primary worry.The Miele hood has a 625 cfm fan. My question was whether or not an inline fan added to my system would help compensate for reduction in pressure I would cause by putting turns in my ductwork or if it would just complicate the whole setup and create more problems than solutions.The ductwork is 10" round. I would place the inline fan near the vent exit and I would operate it with a current sensor so that it would go on automatically when the built-in hood fan was in use.Can an inline fan used in this augmentative way?

2. 
   The_Tennis_Court_Builder_...on_t | Jan 18, 2002 08:08pm | #6

   *Yo cook,I cook without a fan...I would think 625...even with your duct loss would be great compared to 0.near the stream,aj

3. 
   teo_ | Jan 23, 2002 11:37am | #7

   *Yeah, that's just what I was thinking aj. But I would hate to watch 625 cfm of heated air blasted outside every time I flipped that on. That would be like heating my entire house every 15 minutes!Would overrunning the duct hurt anything, aside from lower the output?

4. 
   cook | Jan 23, 2002 06:25pm | #8

   *That's funny, you guys! I am a professional cook and I do some serious cooking at home. The reason you want to vent is two-fold: first, if you cook in an unvented kitchen, the airborne fat and smoke molecules are likely to settle on your countertops and cabinets, which is not my prefernce; second, smoke is carcinogenic and, while it is true that you do not often cook on a range top with smoke, it is not unusual -- I often Wok-smoke halibut or herring and sometimes cook Indian spice mixes in smoking oil.As for heat release, I usually have the opposite problem: when cooking, the kitchen gets TOO HOT. Even New York city kitchens, from my experience, get too hot when doing serious cooking, so a little venting is not a bad thing.cook

5. 
   Alan_Kim | Jan 23, 2002 07:09pm | #9

   *Our kitchen can be isolated from the rest of the house.Closing two doors and a pocket door does the job.The kitchen area has an entrance door and two windows.An exhaust hood is planned for the island counter that houses the range but in the meantime a box fan at the sink window exhausts the cooking smog effectively while the other window (or the door) brings in sufficient makeup air.With the heat involved in cooking, sucking out conditioned air is not a great concern, especially in a closed off kitchen. Actually we find it refreshing to bring in cold air while cooking, even during the winter.Even with a soon to be installed range hood, we will continue to use one or both windows to bring in makeup air.As for cooking fumes and health, I read a while back China has a high rate of lung cancer that may be related to oil fumes generated from wok cooking. They also smoke a lot of cigarettes over there, but it's something to think about. Sizzling a hamburger patty or bacon on a cast iron skillet would have the same effect.We know a couple from China who owns and operates a restaurant.They recently built a very expensive house.When I asked them if they do any cooking at home, the answer was a "no".

6. 
   Tim_Rice | Jan 24, 2002 04:19pm | #10

   *I don't know if what I do is "serious" cooking, sometimes it is comical, but when I do cook and have the exhaust fan going, I open a kitchen window to provide make up air.In commercial kitchen (that meet code) outside makeup air is required. In residential kitchens, code does not require any makeup but does require 100 cfm intermittently or 50 cfm continuously exhausted, not recirculated.Ever see a fan curve? You would have to know at what ESP (external static pressure) that 625 cfm is rated. 625 cfm in a 10" round duct (smooth) will have a friction loss of 0.21" per 100' of equivalent duct. Dirty filters will have a pressure drop of about 0.2" and the roof cap/wall cap and backdraft damper will account for another 0.1" Add up all the straight duct lengths, add 5' for every 22.5 or 45 and add 10' for every 90 degree turn. Crunch the numbers and see what you get. If you have the fan manufacturer and model number, I can tell you exactly what flow you'll get.

7. 
   The_Tennis_Court_Builder_...on_t | Jan 25, 2002 04:47am | #11

   *fo get the math for me. I would get plenty of air exhausting.This thread is like Al Gore figuring out his policies...I am a GW Bush kinda fan guy...near the stream,aj

8. 
   teo_ | Jan 29, 2002 12:45am | #12

   *Is that the fan that increases the exaust by 42 billion cubic feet, requiring more domestic oil drilling to power it, while cutting the intake air to stimulate cooking growth? And about that installer Fanron...

9. 
   Thomas_Sawyer | Feb 03, 2002 05:46pm | #13

   *Just another log for your fire. None of this matters as you'll never have to deal w/ commercial code guys and health inspectors but for those of us who have. Do all the math you want-i've seen all kinds of cool math that didn't add up to squat- but then again I'm a mathematical retard. Hood fans are supposed to be balanced.They make this neat meter that the hood guy holds over my grill, burners, and rotisserie oven. takes his thing does his math says its all good. Now here's the kicker- after he does the math he turns on the hood and sets off a smoke bomb. Even math guys like to see where the smoke goes and how fast it gets there. If you have access to all the ducts-which you have to if you are putting it in. Hook it up and burn the crap out of something where does the smoke go and how fast does it get there. Now your hood is or is not sufficient, then buy the in line blower if needed if not throw a log on the stove kick back and drink a high life.(it is the champagne of beers after all) Last note- those scrubbers you talk about work (sort of) but they have to be cleaned. You will end up with grease in all the pipe you install over time your in line fan will end up coated w/ grease. Think about how you will clean it- or who will clean it when you design it. Much like the theory matter can neither be created or destroyed/grease can not either- every few years put a bucket under your hood and flush degreaser and hot water thru your system. Most people ignore their home systems and efficiency will drop, fans will gather build up and go out of true and someday that log might light that grease up and whoof. Happy smokin.

10. 
    bobl_ | Feb 05, 2002 05:02pm | #14

    *If memory serves me (not always the case) Thermador has fans that can be mounted outside. Page 5http://www.thermador.com/productspecs/PDFs/ventspecs.pdfDid you post on Cooks site in kitchen equip? A while back there was an appliance guy who was participating.