Frequent UV and Filtration Questions in Schools
Posted on Tuesday Sep 01, 2020 at 11:26AM in General
Q: Can the UV lights be powered by the HVAC unit transformer?
Q: Does the light have to stay on 24/7 or can it be cycled with room occupancy?
Q: Does the UV light kill all contaminants on the filter or do techs still need to change filters with caution?
The UV light is very effective at breaking down surface and airborne biologicals. It is also intense enough that it can eat through the fibers in an air filter. Because of this, the UV should not be shining directly on an air filter. So, air filters will still need to be changed at the frequency required to maintain system efficiency and cleanliness. Techs should practice caution while changing air filters. Using proper PPE and by disposing of the air filter directly into a bag that will contain any contaminants that can fall from the air filter, will provide a safer environment for the servicing technician.
Q: How high of a MERV rated filter can I put in my HVAC unit?
ASHRAE recommends that MERV 13 air filters should be the minimum used, unless the system cannot handle the added resistance that is present with a high efficiency filter. There are several different factors that determine if using a MERV 13 filter is possible. Things like the blower performance, filter rack size, size and design of ductwork, number and type of registers, or additional factory installed accessories (ventilation, smoke detectors) all add to the total amount of airflow resistance in the system. Each HVAC equipment manufacturer publishes how much resistance a unit can handle. As long as the air filter doesn’t cause the overall system to exceed the manufacturer’s specification, higher MERV rated filters can be used.
Q: What is a filter MERV rating?
MERV is an abbreviation for Minimum Efficiency Reporting Value. The MERV rating tells you how effectively the filter traps small particulates you do not want to circulate through your HVAC system such as dust, pollen, mold, and other irritants. The higher the MERV rating, the more efficient the filter will be in trapping the airborne particles as shown below.
Q: Do filters have the same pressure drop (resistance) as they used to have?
The media used in air filters today tends to allow for higher MERV ratings with the same or less restriction than older, less efficient filters.
Q: Should my UV light have a door shut off switch?
It is not required, but strongly suggested to ensure the light is off during service. Do not look directly at the UV light bulb during service.
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