Arkansas HVACR NewsMagazine January 2020

should also be noted that a fan in the on position can create re-evaporation of moisture on the coil and potential misting. 2. Item (#3 investigator) “One of the first issues noted … was a significant bypass of the HVAC units filtering systems. These bypasses were allowing dust and debre to bypass the filtering systems. Also, the dirtier the filters get, the more particulate would bypass the filter. The metal filler plates actually had a significant amount of filth…” Potential Problem: A poorly installed return air and filter system definitely allows unfiltered air to reach the coil. The result is an increasingly dirty coil. The dirty coil restricts air flow and reduces heat transfer. This is a cycle of increasing bad results. Even though the MFD, Maumelle Fire Department, may have been changing filters when the filters appeared dirty, dirt entering the system through the gaps in the return air was sufficient for HHL, Healthy Homes of Louisiana, to note “a significant amount of filth…” 3. Item (#2 investigator) “ The MFD stated this unit was only in the ON position for a short period of time on the initial evaluation due the coil being frozen and during this investigation due to the HVAC service contractor having shorted the system .” Potential Problem: Even though the MFD noted the unit was only in the “ON” position for a short time, all three investigators

found it in the on position on October 2, November 7, and December 3. So, someone must have been setting it in the “ON” position or it was never turned from “On” to “Auto”. Either way, it is important to recognize why it was in the “On” position in the first place. The MDF stated that the “coil was frozen”. Putting the fan in the “On” position is frequently done to help defrost the coil and keep the system operating when the unit is undercharged or there is restricted air flow and the service tech is a “day away”. So why was the coil frozen? Perhaps, the charge was low, perhaps the filthy coil was reducing air flow and heat transfer. We did not speak with the tech but one thing is sure, it was an HVAC screwup. Now it could be that the unit had a refrigerant leak from the factory or that the installer improperly brazed the copper tubing. In either of these possible scenarios, it is possible that the vacuum was either not performed or improperly performed. 4. Item (#2 investigator) “… humid air is entering through the un-insulated soffit…” Potential Problem: The reference is to the sealed attic. Actually the attic is suppose to be sealed but #2 investigator found areas of air leakage. The result should be the same, an attic that is within the thermal envelope of the structure; which, should also be an attic that is within the air barrier of the structure. Hot humid air was allowed to enter the attic creating the potential for high humidity.