Share thisOur physical plant personnel have requested to remove the HVAC air filters located at the room exhaust grill. They state that the new HVAC exhaust system that was recently installed doesn't have the same contamination/exposure problems during PM as previous units. We have a conventional facility, no biohazards, negative pressure rooms, rodents, rabbits, and large animals. It seems amazing to me that these filters aren't required to keep the ductwork and exhaust fans clean; but I don't see an animal health-related reason to keep them. Please let me know if I am overlooking a reason to keep the filters. Thanks.
I find it interesting that the physical plant department is asking permission to remove the filters. Generally, they are responsible for decisions affecting this type of equipment. The filters are required to protect the duct and associated equipment in the exhaust side of your air handling system. If, because of design changes, physical plant feels the filters are not required, they should simply tell you that they are no longer needed rather than ask you if they can be removed. Because they are questioning the filter removal, I am assuming that maintenance performs the filter change rather than the animal care staff, although from experience that would not be very common.
Some facilities have located the “room filtration” above the ceiling such that the animal care staff no longer needs to perform this type of maintenance task. This is done with the knowledge that a small section of ductwork would be subject to dust and dander buildup over time. There are three key issues with this approach. One is to insure the duct can be accessed for cleaning if needed. The second would require that devices potentially affected by the dust and dander be located on the down stream side of the filter bank or be specified to handle the dirty environment. Third is a system by which the filters may be removed without exposing the maintenance worker to high levels of allergenic material (or PPE is required) as well as preventing this material from being transported all over the above ceiling space.
From your perspective, which is that of animal and staff well-being, I would inquire as to the schedule on which the remote filters (if installed) will be maintained. This is a very valid question as they are not in the room and are not clearly visible. Slowly eroding exhaust performance over time due to filter load could cause room balance and air change issues. You stated that the rooms operate negative with respect to the adjacent spaces. If the filter bank for the room is not maintained properly, the loading would eventually reduce the exhaust flow from the room — which could then result in the room becoming positively pressured. Even if your supply system tracks the exhaust system to maintain the negative pressure, eventually, that equipment will reach its limits and fail to compensate beyond that point. Remember, the entire time that the supply air is being reduced to maintain your negative pressure room, you’re also reducing the air changes per hour within that space. Further up the chain is the air handling plant. That usually consists of large belt driven blowers, huge damper boxes, and potentially a heat recovery system. The majority of these