Past couple years I been taking psychrometric readings in our district buildings during the cooling season. ( from Heating-to-cooling transition, to, cooling-to-heating trans.) I been doing this just for kicks, and to learn something about our buildings. What I found out was that our buildings generally run about 45% RH at 76* indoor air temp with no moisture difference from the outside air. We have chilled water circulated through fan coils in each classroom. 45* chilled water temp, and DDC controlled 3-way diverting valves, modulating to maintain the warmest coil temp possible, and still keep the room at setpoint. Consequently, the coils dont sweat, only the manifolds of the coils do a little, but only enough to stain the drip pan a bit, not puddle and reach the drain.
Floors are carpeted, and generally about 4-5* cooler than the air temp, puting the carpet RH at about 50%. Maintenance director insists there is no mold problem in the district, yet I find what I believe to be ripe conditions, and we have 3 yr old school buildings developing their own smell.
Ambient air in this country seems to be about 60 gr. water per lb. of air most days
Other consernes of mine are operating habits. We shut down the chiller from 3pm to 7am every day, so at least we get a bit of dehumidification in the am when valves modulate wide open, but none the rest of the day. Local Carrier techs dont like the habit bldg. engineers have of running warm coils this way either. We do run 40% prop glycol in the systems. When they clean the carpets, we make no attempt to run cooling longer to aid in drying.
What do you guys think?