J. Oberling, B. Weaver

I checked on the TCS chiller this morning and added 350mL of water to bring the level from 5.0 to 8.9.  I then noticed that the mesh filter seemed to by pushing up out of the reservoir by a good bit.  I reseated the filter and noticed the level had dropped to 6.3.  There was still 50mL of water in the cup, so I added that to the chiller and observed the mesh filter.  Sure enough, the filter puffed up.  There is a large air gap between the top of the water in the reservoir and the spot that the filter seats into.  What I think is happening is when we fill the chiller, that air between the water and the filter has no where to escape quickly (probably due to the amount of water moving through the filter).  This creates an air bubble between the water and the filter that then influences the fill reading on the front of the chiller (hence why the reading went down when I simply reseated the filter).  I have a suspicion that the chiller has not been losing water, we just haven't added enough since the system flush to completely fill it, and when we do top it off we're creating an air bubble that influences the fill level reading.  We then think we've topped the chiller off when in actuality we haven't; as that air bubble slowly works its way out the level reading "drops," thereby making us think we're losing water.

I ran this by Betsy and found she was starting to suspect something similar.  We went out and removed the mesh filter and then topped the chiller off, then replaced the filter.  It took 600mL of water to move the indicator from 6.3 to 8.3, which is much less than we've seen in the past; if you look at the log on top of the chiller it can be seen that there are instances where we fill w/ 250mL of water and move the indicator from 5.0 to ~9.0, which is much less than the 600mL is took to go from 6.3 to 8.3.  This suggests that what I wrote above is correct, we haven't been fully topping off the chiller but have been fooled into thinking we have by an air bubble of our own creation influencing the reading of the chiller fill level.  One of us will check the chiller at the end of the day to check the chiller water level and see if we still need to add water (water has been added every morning and evening for every day this week).

Total water added this morning was 1000mL, and this moved the indicator from 5.0 to 8.3.