4/5/1994 - Laserfiche WebLink

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r APR m 1994 boar. 92 FACE .56 9. CONCLUSIONS We have concluded from our investigation and study that the existing HVAC systems in this building are not capable of maintaining acceptable indoor air quality by today's standards for the following reasons: A. Almost all of the air handling systems have inadequate outdoor air flowing into the building as prescribed by ASHRAE 62-1989. Some of the air handling systems have no outdoor air connections. If outdoor air connections were added these units would not have the capability to remove the additional moisture. B. None of the air handling systems have any type of positive humidity control such as reheat or face and by-pass damper. Humidity readings taken throughout the building were 68% or greater. These readings were taken in February when there was not much sensible load but without positive humidity control, these units will not remove enough moisture from the air at any time during the year. C. None of the air handling systems are equipped with adequate filters required by today's standards. Current acceptable practice is to install high efficiency filters in all air handling systems. The existing air handling units do not have the capacity of receiving or functioning with high efficiency filter. D. All air handling systems have or have had standing water in the condensate pans. When built, these units were not available with fully drainable pan. E. In areas where above ceiling fan coil units (three story area) are the only source of cooling there. inadequate air circulation. These units are very old and are left from the original hospital building (possibly 30t years old). F. Chilled water temperature being circulated is 51°Ft not cold enough to accomplish the necessary dehumidification. This is caused by controlling the chiller from return water temperature a trial modification made to reduce the cost of electricity. G. Resistance to chilled water flow in many of the fan coil air units and the air handling units is so high that the unit coils do not receive enough chilled water flow. This probably caused by scale build-up or undersized pipe in the original design. H. Since part of the system is four pipe (have a hot water coil and a chilled water coil) and part is two pipe (having a combined coil) the change over from cooling to heating is very difficult This makes it impossible to maintain conditions during seasonal changes. I. A large percentage of the ductwork contains dirt and must be cleaned or replaced. J. Chilled water system is not fully redundant and only two small old chillers back up the existing chilled wathr system. In view of the foregoing, it is not considered practical or in most cases possible to retrofit the existing -system to a condition that will maintain adequate indoor air quality. 32 - M