Vent-A-Hood FAQ
    What is the purpose of kitchen exhaust system cleaning?
  • The primary purpose of grease hood and grease exhaust system cleaning is to prevent fires by removing the fuel (built up grease) from your exhaust system. This includes the hoods, grease removal devices, fans, ducts, filters and other appurtenances (the Exhaust System).

    How often do I need to clean my Vent-A-Hood?
    • There is some confusion about how often commercial kitchen exhaust systems cleaning is required. The answer is determined by the code or laws adopted by your city, county, or state (municipality). The municipality often assigns a Fire Marshall or Fire Inspector to inspect and enforce those codes.
       
    • It is very typical for a municipality to adopt the standard written by the National Fire Protection Association (NFPA) as the local law or code for building and cleaning commercial kitchen exhaust systems. The NFPA is an independent organization, not an arm of the government. The standard that the NFPA has written concerning commercial kitchens is NFPA 96. Again, NFPA 96 is a standard written by an independent organization, not a law or code until it is adopted as a law or code by the municipality where the cooking establishment is located. Since NFPA it the standard most widely adopted into law it is the only standard we will address.


    NFPA 96 2011 Standard - Table 11.3
    Solid Fuel (wood, charcoal) Monthly
    High Volume (24 hour operations, charbroiling, wok cooking) Quarterly
    Moderate volume cooking Semi -Annually
    Low volume cooking (churches, day camps, seasonal operations, senior centers) Annually
    Who requires that my kitchen exhaust system be cleaned?
  • Typically; there are several agencies or institutions that will require that the kitchen exhaust system be cleaned.

    The Fire Marshall
    Typically, the city or the county ordinances appoint a fire Marshall or fire inspector to inspect and insure that the exhaust system is maintained and cleaned free of grease laden deposits that may present a fire safety hazard. Typically, the NFPA Standard 96 is adopted as code by the authority having jurisdiction (AHJ).

    The Food or Health Inspector
    The city or the county ordinances appoint a food or health inspector to inspect and insure that the exhaust system is maintained and cleaned free of grease laden deposits that may present a food or health safety hazard. Typically, the NFPA Standard 96 is adopted as code by the authority having jurisdiction (AHJ).

    The Insurance Company
    Many insurance companies will require that the building owner of the food service operator provide proof of the exhaust system cleaning prior to insuring the building or the operations.

    The Building Owner / Property Manager
    Most building owners / property managers will require that the food service operator provide proof of insurance for the building. This will typically require proof of regular exhaust system cleanings prior to obtaining insurance and as a condition of maintaining building insurance.

    The Food Service Operator
    Experienced food service operators understand the down side and extreme expense related to a kitchen grease fire. In addition to eliminating interruptions to business and the restoration expenses after a fire, regular grease exhaust system cleaning contribute positive benefits of maintaining a good working environment for their kitchen staff. Hydro-Clean has found that the most large chains and very successful food service establishments are very conscientious about regular kitchen exhuast system cleanings. 
    What does a kitchen exhaust system cleaning service include?
  • Hydro-Clean recommends that you request that the following services be performed at a minimum of two (2) times per year (high volume, solid fuel, char broiling, and wok require more frequent cleanings):

    • Clean the entire kitchen exhaust system (hoods, grease removal devices, fans, ducts, filters and other appurtenances) to bare metal.
       
    • Capture and properly dispose of all waste water.
       
    • Clean area and floor of foot prints.
    Optional services may include:
    • Rinsing grease from roof
       
    • Rinsing grease from parking lot
       
    • Cleaning the grease trap
       
    • Replacing broken baffle filters
       
    • Replacing filters on make up air unit
       
    • Cleaning of the ceiling
       
    • Cleaning of the tile floors

     



    My last Vent-A-Hood cleaner did a bad job. Can you clean my kitchen exhaust system?
  • The short answer is, "Yes; but it will be more expensive then if you had performed regular thorough cleaning."

    At Hydro-Clean, we compare neglected kitchen exhaust system cleaning to neglecting trips to the dentist for teeth cleanings. If trips to the dentist are neglected the consequences can be severe and full recovery impossible. The same is true in Vent-A-Hood cleaning.

    Unfortunately, more often than not, some permanent damage is done by cleaning up after neglect. The chemicals used is harsher and the pressure washer setting is high. Scrubbing and scraping leaves scratches.

    We advise all owner/operators to inspect their kitchen exhaust system the day after cleaning:
    • Tip back the fan and inspect the duct
       
    • Inspect the fan blades
       
    • Remove a filter and inspect the plenum. 
    Why is my kitchen hot? The fan seems to be running.
  • Trouble shooting hot and smoky commercial kitchens when fans seem to be running:

    1. A worn and cracked belt will slip on the pulleys causing poor suction of the grease exhaust system resulting in a hot kitchen. We recommend changing the belts AFTER each kitchen exhaust system cleaning.

    2. Loose or broken fan belts are the number one cause of hot and smoky kitchens.


    3. Fans in the kitchen will disrupt the natural rising hot air plume of the cooking equipment and disrupt the draw of the kitchen exhaust system fan. These fans make the kitchen hotter by blowing the heat generated by the cooking operations away from the exhaust fan and back into the kitchen.

    4. Dirty ducts are more of a source of fuel for a fire than a problem for exhausting grease laden air, but grease has accumulated in the bend of the duct restricting air flow. Dirty ducts restrict air flow and cause hot and smoky kitchens.

    5. When pulleys are out of align, belts wear and loosen and the hood does not exhaust grease laden air properly thus making the kitchen hot and smoky.
    Other causes for hot kitchens in Commercial Cooking Environments:
  • 1. INADEQUATE MAKE UP AIR. Apart from a broken fan belt, problems with the make up air is probably the 2nd biggest cause of hot kitchens.

    Things to check include:

    • The belt on the make up air is broken
    • The make up air filters need changed
    • There is inadequate make up air
    There are simple ways to test if makeup air is inadequate. If there is a rush of air into the restaurant each time the door is opened it means more air is being sucked out that is being brought back into the building. This means the kitchen exhaust fan is creating negative pressure in the building. In some instances, only a company that specializes in testing and balancing commercial kitchens can resolve the problem. If you are exhausting 400 cfm of air you must be bringing in 400 cfm or you will be exhausting your heated air or air conditioning.

    2. MOTORS RUNNING BACKWARDS. This typically happens with new grease exhaust fans or when a motor has been recently changed. Two hundred twenty volt (220v) motors operate clockwise and counter-clockwise. If the two hot wires are switched the motor will reverse directions. On a grease exhaust fan it will still seem like the fan is blowing air but this is just actually from back pressure and the fan is not properly exhausting air. Generally this is characterized by very weak suction at the hood.

    3. Each piece of cooking equipment has varying hot air exhaust plumes. The hot air plume of a fryer increases significantly when frozen foods are added. The plume of a grill increases when fresh hamburger is added but less significantly than the fryer. Be sure your cooking equipment with the greatest plume is placed in the center of the hood or directly under ducts. Also, be sure that the equipment sits at least 4 inches from the front edge of the hood.

    4. Be sure the air passage between the filters is clear of grease. Improper or infrequent grease filter cleaning may lead to baked on grease and carbon deposits in this area. Hot air must be able to pass through the grease baffle filters. These deposits can be impossible to clean. Built up grease between the grease filter baffles can severely restrict the airflow through these grease filters. This restriction can severely impede the grease and hot air exhaust capabilities of the kitchen exhaust system.

    5. Be sure the pulley is not slipping on the shaft. Check that the allan head screw is tight and that square key bar is in place.
    My Vent-A-Hood is not working.
  • Trouble shooting kichen exhaust systems in commercial kitchens:

    1. This motor compartment let grease and hot air in - both hard on rubber fan belts by causing belts to slip and dry rot of the rubber. Loose, cracked, and slipping belts cause the fan to be inefficient. A fan belt should be able to bend in half backwards without cracking.
       
    2. Broken belts are the most common cause of a grease hood not working properly. You may be able to hear the motor run when you turn on the grease fan switch. This belt broke because the motor and fan pulleys were out of align. We recommend changing fan belts after every hood cleaning.
       
    3. Grease exhaust fan switches sometimes are accidentally not turned back on after service. Always turn the grease fan switch off at the fan when servicing a grease fan belt to avoid someone in the kitchen below accidentally turning it on and causing injury. These switches are located on the exterior of the grease exhaust fan or inside the motor compartment.
       
    4. Many grease exhaust fans are not installed or wired properly. NFPA 96 requires fan to be on hinges and electrical wiring be ran outside the duct in waterproof conduit. This grease fan has a hidden electrical hazard waiting to happen. Be sure you see electrical wiring on the exterior of the fan before tipping or removing the fan from the duct.
       
    5. Electrical electrical wiring should NEVER be ran inside the duct. This grease fan also has a hidden electrical hazard waiting to happen. When the fan is removed from the duct, this conduit can cut the electrical wires, short out, and cause a fire in the grease duct. Be sure you see electrical wiring on the exterior of the fan before tipping or removing the fan from the duct.
       
    Other reasons why a Vent-A-Hood is not working properly:
  • 1. Check the electrical circuit breaker. It may be tripped or bad. If bad, call an electrician for service.

    2. A fan not working because the electrical wire inside the breaker box was loose. Call an electrician for service.

    3. If the grease fan hums or buzzes but does not start, the brushes on the electrical motor may be bad. Call an electrician for service.

    4. The fan switch may be bad or have loose wires. Call an electrician for service.

    5. A very common problem just after fan motor replacement is that the 220 volt motor is running backwards. Back pressure makes it seem like the fan is working at the roof, but in the kitchen the exhaust system is functioning very poorly. Call an electrician for service.

    6. A loud clank noise may mean a chuck of rubber is missing from a fan belt or a fan bearing is bad. The top bearing is easily removed and replaced. The bottom bearing is very difficult to remove. Hydro-Clean has a specially designed tool to remove this bottom bearing.


    Why does my kitchen exhaust system fan squeak when I turn on the switch?
  • Trouble shooting kitchen exhaust system fan makeing a squeaking noise in commercial kitchens:

    1. A worn and cracked belt will slip on the pulleys causing a squeaking sound when the fan switch is flipped.

    2. A loose or out of align belt will slip on the pulleys causing a squeaking sound when the fan switch is flipped.
    Fan belts should be changed on a regular basis. Hydro-Clean recommends checking the fan belt at least every 6 months or at each cleaning (which ever comes first). Hot air and grease laden air causes the rubber to become brittle and dry rot. When this happens, the belts slip on the pulleys increaseing the heat to which the belt is exposed. If you run a 24 hour operation we recommend that the grease fan belt be check at least quarterly.

    Hydro-Clean recommends changing fan belts at each cleaning. The reason we recommend this is that steam, water, soap (chemical), and grease from cleaning the fan can contaminate the belt causing it to slip after cleaning. If the belt is already hardened by the heat and grease from the cooking operations there is a very good possibility the belt will break within the next week or two. Always wait until after the kitchen exhaust system fan is completely cleaned before installing a new belt. This will prevent contamination of the new belt from the fan cleaning operations.

    Why is the fan sucking my filters up into the hood?
  • 1. Your fan may be turning too fast. The ASHRAE research report RP-1033 shows that air movement at 500 fpm is more efficient and preferable to 1,000 fpm, 1,500 fpm and 2,000 fpm for removal of grease laden air from the sides of duct work.
    A. Fans turn too fast when the pulleys are the wrong size.
    B. Motors come in 2 speeds, 1725 RPM and 3450 RPM. Make sure you have the right motor and that it is wired correctly.
     
    2. You may need heavier filters. Aluminum filters are considerably lighter than galvanized metal or stainless steel filters. Simply changing your filters may correct this problem.

    3. Your filters may be clogged. The air passage through these baffle filters is restricted due to built up grease deposits. Sometimes neglect prevents this area from being thoroughly cleaned without damage to the filters themselves and filter replacement is required.

    Why is my hood leaking grease?
  • 1. Your fan may be turning too fast. There is an optimum air velocity for removing grease laden air from a kitchen  exhaust system.

    The ASHRAE research report RP-1033 shows that air movement a 500 fpm is more efficient and preferable to 1,000 fpm, 1,500 fpm, and 2,000 fpm for removal of grease laden air from the sides of duct work. If your fan is turning too fast the grease is building up on the walls of the duct and not being exhausted.
    A. Fans turn too fast when the pulleys are the wrong size.
    B. Motors come in 2 speeds, 1725 RPM and 3450 RPM. Make sure you have the right motor and that it is wired correctly.

     
    2. You may have your filters in backwards. Be sure the grease drain holes are facing forward.

    3. Filters must be installed vertically at a 45 degree angle to work properly.

    4. You may have a broken or loose fan belt.

    5. Your fan may not be working.
    A. Is the fan switch in the "on" position?
    B. Is the electrical circuit breaker tripped?
    C. The electrical motor could be bad.
    D. There could be an electrical short or bad ground wire.
    E. The bearings may be frozen on the fan in the motor compartment.

    6. Your grease tray or grease cup may need cleaning.

    7. Your kitchen exhaust system needs cleaning.

“He who wants to change the world should already begin by cleaning the dishes.” ~ Paul Carvel