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  1. #1
    Join Date
    Jul 2014
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    London
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    5
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    Kitchen heat recovery for the purpose of DHW (pre-)heating

    Hello HVAC community,

    I am looking for reliable and hassle free heat recovery system for commercial kitchens.

    I would like to use for the purpose of (pre-)heating hot water.

    All solutions that I found so far get clogged up with grease relatively quickly and had to be remover shortly after installations.

    I wonder whether you have heard / have experience with any heat recovery system that works properly in the kitchen environment?

    Kind regards

    dolph82

  2. #2
    Join Date
    Jan 2016
    Location
    The triangle in the Keystone
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    1,107
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    Hobart uses the system which basically caputures it’s own heat and preheats the booster water with it.

    Just thinking off the top of my head here but are there any kettles or steamers that have a constant flow of hot water going down the drain? You could utilize that somehow. You could disconnect the cold water condensate but you would need to have it automatically turn back on when the d/w wasn’t calling for hot water.

  3. #3
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,571
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    Might look into Munters. They have a wide variety of HX equipment.

    Heat pipes might be another thought. Basically a tube that has one end in the airstream and the other in the water to be pre heated. Tubes have a wick and some sort of refrigerant in them. Works passively.

  4. #4
    Join Date
    Aug 2009
    Location
    Maine
    Posts
    8,096
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    Quote Originally Posted by dolph82 View Post
    Hello HVAC community,

    I am looking for reliable and hassle free heat recovery system for commercial kitchens.

    I would like to use for the purpose of (pre-)heating hot water.

    All solutions that I found so far get clogged up with grease relatively quickly and had to be remover shortly after installations.

    I wonder whether you have heard / have experience with any heat recovery system that works properly in the kitchen environment?

    Kind regards

    dolph82
    I always wanted to install piping in the exhaust hood. free hot water. Maybe

  5. #5
    Join Date
    Feb 2017
    Location
    New York
    Posts
    1,468
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    This may be a far fetched idea, but how about making a manifold and have a few 3/8" soft copper runs on the outside of the hood? Attach them to the hood with epoxy or clamps(trying to keep as much contact as possible), then insulate over the top to hide it and make it look somewhat presentable. Maybe have a sheet metal guy break some stainless to cover it? That way nothing can get fouled up.
    -----Stop, step back, relax and have another go at it.-----

  6. #6
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    20,286
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    Quote Originally Posted by BennyD View Post
    This may be a far fetched idea, but how about making a manifold and have a few 3/8" soft copper runs on the outside of the hood? Attach them to the hood with epoxy or clamps(trying to keep as much contact as possible), then insulate over the top to hide it and make it look somewhat presentable. Maybe have a sheet metal guy break some stainless to cover it? That way nothing can get fouled up.
    I believe theirs a code against that........

    I wouldn't want to take a chance of a broken line sending water into the hot oil!

    Co-gen plants wrap the outside of the exhaust duct to gather more heat!

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,048
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    We made heat pump water heaters with the cooling coil located in the hot spots of the kitchen. Combined with heat recovery on the freezers hot water was free when ever cooling was needed in the kitchen. Worked well but needed more maintenance. Even McDonalds use them as standard equipment where natural gas was not available.
    Failed because it cost more.
    What you describe is a grease trap that needs daily washing.
    Good luck.
    Regards Teddy Bear
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Join Date
    Feb 2017
    Location
    New York
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    Quote Originally Posted by pecmsg View Post
    I believe theirs a code against that........

    I wouldn't want to take a chance of a broken line sending water into the hot oil!

    Co-gen plants wrap the outside of the exhaust duct to gather more heat!
    Funny that you mention co-gen because that was my first notch in the belt.
    -----Stop, step back, relax and have another go at it.-----

  9. #9
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    21,155
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    I've never seen heat reclaim from warm exhaust air. Just thinking about it, it doesn't sound very efficient. Saw something on TV a long time ago where they do that at the residential level in Europe.

    Have seen a few heat reclaim from refrigeration, even re-engineered one system that didn't work right.

    I've always thought that the hot water drain on a commercial dishwasher would be a good source of heat for pre-heating. Never seen one though. Have to be made for ease of cleaning.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

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