Am I getting conned?


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Old 05-11-07, 02:57 PM
J
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Question Am I getting conned?

My kitchen contractor is installing a new range hood as part of our kitchen reno. The ductwork has been rerouted with 2 90 degree bends, 1 of which is just as the duct clears the ceiling. My cabinet installer suggested that it would be better to straighten the ductwork as much as possible. Originally, my contractor agreed to the work - now I am being told that after consultation with the sheet metal people, straightening the ductwork is not needed and the fan will work just fine as it is. Am I getting conned?

Thanks

JaneVictoria
 
  #2  
Old 05-11-07, 03:03 PM
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Maybe.

It all depends on the size (CFM rating) of the hood and what size of ductwork is being installed. It is quite possible that the size and length of the newly proposed ductwork is more than adequate for your hood. It may also be woefully inadequate.

Without knowing the CFM rating of your hood AND the size, length and number of turns in the proposed ductwork I cannot give any better answer.
 
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Old 05-11-07, 03:30 PM
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Some installation instructions specify that you stay under 30 feet and limit the bends to two of 90 degrees. Note: Sharp bends will disturb the clear flow of air. Others simply indicate that where turns are necessary to keep the turning radius as large and smooth as possible and the runs as short as possible.
 
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Old 05-11-07, 03:51 PM
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CFM and duct size

Sorry not to pass along all the relevant info. The range hood is 650CFM and the duct size is 6" where the duct clears the ceiling and runs into the attic. There are 2 90 degree bends and 1 45 degree bend and then the duct runs straight and is vented out the roof. Our kitchen is on the second floor of the house and I estimate the total run of ductwork to be about 12'.

Thanks for the help

JaneVictoria
 
  #5  
Old 05-11-07, 04:27 PM
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Six inch diameter duct is already a bit dicey for 650 CFM. With that much ductwork you might be lucky to realize 400 CFM actual flow.

Is six inch the size of the outlet at the hood or is the contractor using a reducing fitting?

I would feel better if they went to at least a seven inch duct. Better still would be a 3-1/4 by 14 rectangular duct.

What do the manufacturer's instructions have to say?
 
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Old 05-11-07, 04:46 PM
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Update: Am I getting conned?

The outlet size at the top of the range hood is six inches.

The manufacturer's installation guide suggests that all turns and transitions take place as far as possible from the opening, and that a minimum six inch round duct be used. Rectangular ducts require an adaptor.

I have shown this guide to my contractor but he is insisting that his information is correct and that I am worrying about this for nothing.

JaneVictoria
 
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Old 05-11-07, 06:19 PM
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If the duct went straight up and through the roof the 6 inch would be fine. If the duct went up a foot or so and then turned 90 degrees and went another foot or less out the side of the house it would also be okay.

But two 90's a 45 and a total run of 12 feet? Nope, wouldn't fly in my house.

I always go along with the adage that nobody knows more about the equipment than the manufacturer. Your contractor sounds to me like a "know-it-all" or maybe he is just blowing smoke at you because you are a woman. (I detest people that do that.)

I don't know what kind of contract you have or the specific wording, plus I'm not a lawyer so I can't offer any legal advice. Usually contracts are written so that the contractor MUST follow all the installation requirements as set down by the manufacturer of the equipment.

I wish you luck.
 
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Old 05-11-07, 06:53 PM
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Not wanting to get personal, but if you have a father, husband, big brother, uncle, or any male family members or friends, then get them to convey what needs to be done to the contractor. Insist.

Sorry to get off topic here, but as a female I get those blank stares and the feed back from know-it-all males. No offense intended, but there are some who refuse to listen to women. I'm in Appalachia and the problem is pervasive in our culture here.

Perhaps a call to the range hood manufacturer's customer service department to clarify the issue would be best. Record the conversation. Better yet get them to email you what they tell you so that you can provide copies to all involved in this project.
 
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Old 05-12-07, 12:00 PM
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Wink

Im with furd You said the run was 12' and 2 -90o L and a 45oL == 12.5'.
So that makes 24.5' run. What does the paper work with the fan say?? Go with that
 
 

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