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Cooktop Vent Violation

Discussion in 'Residential Mechanical Codes' started by Gordon H., Mar 11, 2018.

  1. Gordon H.

    Gordon H. Registered User

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    My sister In law had major flood damage to her home in Boca Raton. One of the items
    we replaced was the cooktop on the center island in her kitchen. The original was a
    GE Premier 36" cooktop with a Premier downdraft vent. We replaced the cooktop with
    a GE Monogram 36" unit and a new Premier 36" downdraft vent (GE no longer makes
    a downdraft vent in the Monogram series). Now the contractor is telling her, the
    Inspector states the new cooktop/vent is in some kind of code violation and we should
    replace the new cooktop with the original Premier style unit. Both the Monogram and
    Premier units are 36", 5 burner, the largest being 18,000 BTU. The total Monogram
    output is 62,000 BTUs, the Premier is 57,000 BTUs. The vent is rated at 370 CFM.
    I checked the Florida codes and the only thing I could find was a 100 CFM requirement
    for downdraft vents.

    Could someone advise me of what code requirement(s) we are in violation of, and a
    possible solution ( other than another $1,000 on a new cooktop ) ?

    Many thanks.
     
  2. cda

    cda Sawhorse

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    You need to ask directly and nicely to the inspector,,,

    The code book, edition and the sections that are being cited for the violation.

    Then, get a copy of those sections from the city so you can see what they say
    and if they are being applied correctly.

    Plus publish what code and sections they are here, so we can review them also.

    Was the replacement of the appliances part of the work that was permitted??
     
  3. cda

    cda Sawhorse

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    Welcome also
     
  4. Gordon H.

    Gordon H. Registered User

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    Thank you for your reply, I will get that info and post it here.
    I'm not sure what you are asking:
    Was the replace part of the work that was permitted??
     
  5. cda

    cda Sawhorse

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    Was the replacement of the cooktop, told "up front" to the city and permitted
    if needed??
     
  6. Gordon H.

    Gordon H. Registered User

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    This is a vacation home that suffered a burst water supply to one of the bathroom toilets.
    No one was there at the time, and the flooding went unnoticed for several days. The
    damage was extensive. Floors, walls, plumbing fixtures, cabinets in addition to the
    cooktop/vent, were replaced. A permit was obtained for the work. As far as the
    specifics of the cooktop/vent, I'm not sure.
     
  7. cda

    cda Sawhorse

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    Get the code sections and post them,,,

    Should have said also, if they cannot produce them, than there is no violation.

    Have you seen the written violation?? Should say what the problem is.


    Plus makes no sense to tell an owner to install the old stuff??? The violation should say this is wrong fix it, or remove the cooktop.

    Inspector may have suggested a fix would be to install the old one??
     
  8. steveray

    steveray Sawhorse

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    Maybe makeup air for the new hood? >400cfm?
     
  9. mark handler

    mark handler Sawhorse

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    Range Hood Fan Size
    The basic rule of thumb when determining the fan size of a range hood is that it should move a minimum of 100 CFM of air for every 12” of stove width. So if you have a 30” wide stove, you would need a range hood with a fan that moves at least 250 CFM of air:
    2.5′ wide stove x 100 = 250 CFM minimum range hood fan size
    Room Size
    You should also take into account the size of your kitchen in cubic feet when calculating the size range hood fan needed, since a larger kitchen needs more venting to clear the air than a smaller room.
    A range hood should be able to exchange the air in the kitchen at least 15 times per hour or every four minutes. For example, if your kitchen is 16’ long x 16’ wide with an 8’ ceiling, it would contain 2,048 cubic feet of space:
    16’ wide x 16’ long x 8’ high = 2,048 cubic feet
    To find the fan needed for your size kitchen, multiply the number of cubic feet in the room by the number of air exchanges (15), then divide by the number of minutes in an hour (60).
    For example:
    2,048 cubic foot room x 15 air exchanges = 30,720 cubic feet moved per hour
    30,720 cubic feet ÷ 60 minutes = 512 CFM range hood fan or higher
    An easier way to make the calculation above is to divide the number of cubic in the room by four minutes:
    2,048 cubic foot room ÷ 4 minutes = 512 CFM range hood fan or higher
    Gas Stove
    The burners on a gas stove produce a lot more heat than those on an electric range, so a kitchen with a gas stove requires a larger capacity range hood vent fan.
    To calculate the fan sized needed for a gas stove, combine the BTU ratings for all the burners on your stove (gas burners range from 5,000-15,000 BTU per burner, with an average of about 10,000 BTU per burner and a total of about 40,000 for a standard 4-burner stove), then divide by 100 to find the minimum CFM needed for a kitchen with a gas stove. For example:
    40,000 BTU gas stove ÷ 100 = 400 CFM range hood fan or higher
    Range Hood Ductwork
    The size, shape, length, turns, and cap on the range hood ductwork adds resistance which reduces the amount of air the vent fan can move, requiring additional CFM for the fan.
    When using smooth, round 8” diameter, metal pipe, add one CFM per foot of pipe, plus 25 CFM for each elbow, and 40 CFM for a roof cap.
    For example, if the vent pipe was 10’ long with two elbows and a roof cap, you would need to add 100 CFM more to the fan size ratings above:
    10 pipe length + 25 elbow + 25 elbow + 40 roof cap = 100 CFM
    Calculating Range Hood CFM Vent Fan Size
    To make the final calculation, take the larger of the CFM rating for stove width, room size, and stove burner. Add the additional CFMs needed for the ductwork to arrive at the minimum CFM range hood to buy.
    In the examples used above, if your kitchen has a 30” stove (250 CFM minimum) in a 16’ x 16’ x 8’ room (512 CFM minimum), and a 40,000 BTU gas stove (400 CFM minimum) you would want a fan rated at 512 CFM or higher, plus 100 CFM for the ductwork for a total of 612 CFM or more.
    The burners on a gas stove produce a lot more heat than those on an electric range, so a kitchen with a gas stove requires a larger capacity range hood vent fan.
    To calculate the fan sized needed for a gas stove, combine the BTU ratings for all the burners on your stove (gas burners range from 5,000-15,000 BTU per burner, with an average of about 10,000 BTU per burner and a total of about 40,000 for a standard 4-burner stove), then divide by 100 to find the minimum CFM needed for a kitchen with a gas stove. For example:
    40,000 BTU gas stove ÷ 100 = 400 CFM range hood fan or higher
    Range Hood Ductwork
    The size, shape, length, turns, and cap on the range hood ductwork adds resistance which reduces the amount of air the vent fan can move, requiring additional CFM for the fan.
    When using smooth, round 8” diameter, metal pipe, add one CFM per foot of pipe, plus 25 CFM for each elbow, and 40 CFM for a roof cap.
    For example, if the vent pipe was 10’ long with two elbows and a roof cap, you would need to add 100 CFM more to the fan size ratings above:
    10 pipe length + 25 elbow + 25 elbow + 40 roof cap = 100 CFM
    Calculating Range Hood CFM Vent Fan Size
    To make the final calculation, take the larger of the CFM rating for stove width, room size, and stove burner. Add the additional CFMs needed for the ductwork to arrive at the minimum CFM range hood to buy.
    In the examples used above, if your kitchen has a 30” stove (250 CFM minimum) in a 16’ x 16’ x 8’ room (512 CFM minimum), and a 40,000 BTU gas stove (400 CFM minimum) you would want a fan rated at 512 CFM or higher, plus 100 CFM for the ductwork for a total of 612 CFM or more.
    https://www.todayshomeowner.com/how-to-calculate-kitchen-range-hood-fan-size/
     
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  10. cda

    cda Sawhorse

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    So how about a downdraft??

    Per manufacture or does IRC address it??
     
  11. mark handler

    mark handler Sawhorse

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    IRC 2012
    M1503.2 Duct Material
    Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.
    Exception: Ducts for domestic kitchen cooking appliances equipped with down-draft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe and fittings provided that the installation complies with all of the following:
    1. The duct is installed under a concrete slab poured on grade;
    2. The underfloor trench in which the duct is installed is completely backfilled with sand or gravel;
    3. The PVC duct extends not more than 1 inch (25 mm) above the indoor concrete floor surface;
    4. The PVC duct extends not more than 1 inch (25 mm) above grade outside of the building; and
    5. The PVC ducts are solvent cemented.
    M1503.3 Kitchen Exhaust Rates

    Where domestic kitchen cooking appliances are equipped with ducted range hoods or down-draft exhaust systems, the fans shall be sized in accordance with Section M1507.4.

    M1507.4 Local Exhaust Rates
    Local exhaust systems shall be designed to have the capacity to exhaust the minimum air flow rate determined in accordance with Table M1507.4.
    TABLE M1507.4 EXHAUST RATES --Kitchens 100 cfm intermittent or 25 cfm continuous

    M1503.4 Makeup Air Required
    Exhaust hood systems capable of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be automatically controlled to start and operate simultaneously with the exhaust system.
     
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  12. cda

    cda Sawhorse

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    Never saw a downdraft install, not my area,

    But where is the exhaust fan at normally??

    Built into the appliance

    Or some where in the exhaust duct system?
     
  13. Msradell

    Msradell Sawhorse

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    Everybody's missing the point that the inspector just wants the old cooktop installed. It was still 36"and had a downdraft fan so those items are not issues. The difference is new one is a little higher BTU but??

    Answer you when have suggested the OP needs to get the code reference that the inspector is referring to when he saying that it doesn't meet code.
    They are normally built into the appliance although there are some that mount in back of the cooktop. Most of them are fixed location although some of the fancier ones go up and down automatically.

    The fan for them is either under the cabinet or in the basement or other remote location. They still sent directly to the outside like any other type range hood would.
     
    cda likes this.
  14. Gordon H.

    Gordon H. Registered User

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    The house is built on a slab, the downdraft is vented via pvc under the slab to the outdoors. The ducting is to code and hasn't been changed since the original downdraft. The original cooktop was a 36" gas unit, the new cooktop is a 36" gas unit. The old and new downdrafts were/are 36"
    The CFM of the new downdraft is 370.
    M1507.4Local exhaust rates.
    Local exhaust systems shall be designed to have the capacity to exhaust the minimum air flow rate determined in accordance with Table M1507.4.
    Table M1507.4 states:
    Kitchens 100 cfm intermittent or 25 cfm continuous

    I see no reason why this installation isn't up to code.
    ...still waiting to hear from the inspector
     
  15. Gordon H.

    Gordon H. Registered User

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  16. cda

    cda Sawhorse

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    So what code section did the inspector say it was in violation of??

    And what was the specfic violation/ problem?
     
  17. Gordon H.

    Gordon H. Registered User

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    Still waiting to hear from the inspector as I stated above
     
  18. cda

    cda Sawhorse

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    Missed that

    Just let us know
     
  19. Gordon H.

    Gordon H. Registered User

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    It's been a while and this still hasn't been resolved but I have been having communication with the inspector.
    He replied:
    My decision is in accordance with the hood manufacturer’s installation manual. Code reference FBCR-M1307.1.

    M1307.1 is about as vague and general as it gets:
    Installation of appliances shall conform to the conditions of their listing and label and the manufacturer’s installation instructions. The manufacturer’s operating and installation instructions shall remain attached to the appliance.

    I pressed him to be a little more specific, and today I finally received a definitive answer:
    This hood shall not be used with an open flame cooktop as per manufacturer manual.

    This is where it get's interesting. I have read through both the installation and user manuals so many times, I can recite it from memory...nowhere in either manual does it state anything even remotely about not being used with an open flame cooktop. As a matter of fact, the install manual states the downdraft vent and cooktop can share the same electrical outlet if used with a Monogram gas cooktop (the cooktop we are using with it).

    I don't know if I mentioned it, but this is my sister-in-law's vacation home in Boca and we are in NY so I haven't been physically able to view the installation (only some pictures) but here's what I think may be happening:
    Either:
    1. The GC bought a different downdraft vent than the one we spec'd out (we will check his invoice tomorrow but the pictures I have seen look like its the correct unit).
    or
    2. The inspector is looking at the wrong manual - the original downdraft vent was a POS, the manual may have still been around somewhere and possibly that is what he was looking at.

    I can't think of any other explanation.
     
  20. cda

    cda Sawhorse

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    Getting closer!!!


    Was the old cooktop open flame??
     

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