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  1. #1

    Fresh Air intake

    I manage a commercial building that is only 4 years old. Our HVAC system is one that runs continually, and adjust air flow with dampers that receive a signal from sensors located throughout the building. My staff is continually ill with respiratory issues. They all say this clears up when they are home.
    We've had a great deal of trouble with the HVAC system getting it to function properly and now I am concerned that we are not getting fresh air into the building. We are on the top floor with no opening windows or doors, and in reviewing the blue prints for the facility I do not see any air intakes from outside the building.
    I have looked over and over above the ceiling and I do not find an air intake from the outside. I know little about this subject so, that is why I elected to reach out here. Should I NOT have fresh air intake from outside the building? It appears I am simply recirculating the air in the building.

    Anyone have an answer?

    Thanks,

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,645
    What is your climate? How many occupants and sqft. of space? Comparing inside/outside dew points and number occupants will provide info on natural fresh infiltration. You should have a fresh air intake to change the air a minimum of 4-5 hours typically.
    Regards TB
    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"

  3. #3
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,156
    Have a look on the Internet or in the phone book, there's companies out there who's sole purpose is air monitoring. It'll cost a couple bucks, but then you'll know what's in the air, before you start throwing money around at a solution.
    You could be right, perhaps a case of sick building syndrome.

  4. #4
    Quote Originally Posted by teddy bear View Post
    What is your climate? How many occupants and sqft. of space? Comparing inside/outside dew points and number occupants will provide info on natural fresh infiltration. You should have a fresh air intake to change the air a minimum of 4-5 hours typically.
    Regards TB
    our square footage is approximately 20,000 climate is typical north east. Winter time 20's 30's moderate humidity, summer time can stay 80's to high 90's. Staff numbers are 12-15. Should I not have some sort of outside air introduced to our system either way?

    Thanks for the response.

  5. #5
    Join Date
    Aug 2003
    Posts
    907
    A good way to get a clue as to what's going on is to measure CO2 (e.g., co2meter) and particulates (e.g., Dylos).

  6. #6
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    1,002
    What type of systems do you have ..are they Rooftop units? or package units that sit on the floor? what type of controls you you have?

    Air ventilation is one thing most people pick first...but i would check cleaning procedures, what types of chemicals are used etc..

    Who does your maintenance? are the filters and coils clean?

    When did this start happening?

    do you have a lot of dust around the vents? do you have a lot of plants?

  7. #7
    Join Date
    Jan 2007
    Location
    Stongsville Oh
    Posts
    948
    We still haven't heard what type equipment you have. If you have packaged roof top units most have an economizer that brings in OA based on a percentage setting on the economizer control. This means a constant 20% OA or more (or less ) depending on the setting. Have your service contractor see what it is set to. This is a bare minimum. Next step is to install IAQ sensors and increase OA based on air quality. This can save energy because min OA can be reduced during low CO2 periods but increase OA during hi CO2 periods. We sell install and service temperature control systems and it is amazing to see how high the co2 rises during periods of high occupancy. We usually set the system to begin increasing OA at 800 ppm and full open at 1000 ppm. If you have VAV system you need to open the terminal unit based on the zones co2 reading. There are variables including is the equipment sized to handle the load of increased OA. Limiting the econo opening during high CO2 to say 50% can reduce the system load but take longer to affect the high CO2. Exhaust fans in the equipment controlled by building static pressure will also help to remove the air from the space. Looking above the ceiling will not help because air will not be introduced there. Hope this helps.
    ckartson
    I didn't write the book I just read it!

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