Help With Liebert 3000 Unit
Help With Liebert 3000 Unit
(OP)
We have a room that is being converted to a calibration lab. The environmental conditions that have to be met are 68 F +/- 5 and less than 55% RH. A Liebert 3000 unit was installed. The installer left the setpoints at 68 F & 40% RH. The Liebert display reports the actual temperature & humidity are near these values. However, a chart recorder in the room says the temperature is 69 F & RH is 65%.
I know very little about HVAC and the project engineer will probably contact the installer. However, for future reference & to gain additional knowledge, how should we adjust the setpoints to achieve a RH less than 55%?
Thanks.
I know very little about HVAC and the project engineer will probably contact the installer. However, for future reference & to gain additional knowledge, how should we adjust the setpoints to achieve a RH less than 55%?
Thanks.





RE: Help With Liebert 3000 Unit
65% sounds excessive, but you should be able to maintain 50%.
Usually labs are pressurized to prevent infiltration and therefore outside humidity from entering the space.
You would be better of having the tech adjust the setpoints, or better yet a factory rep.
RE: Help With Liebert 3000 Unit
Put your chart recorded and the sensor for the Liebert in close proximity to each other. If the chart reader is still reading a different measurement, have a tech come in to calibrate the instruments/sensors and verify the actual space conditions.
RE: Help With Liebert 3000 Unit
my info comes from Henry Fudge from Leiberts Training Center in Columbus,Ohio
RE: Help With Liebert 3000 Unit
Also, the room is not tight. There is no vapor barrier. So in-leakage is an issue. The room that is becoming this mini-lab is a room that served as storage for another lab. If this is an issue in 75 F weather, I know we are doomed during summer.
RE: Help With Liebert 3000 Unit
I have a redundant pair of 40 ton industrial DX models doing a telco room data centre, and the client was pushing for 67F as a setpoint as the old systems had poor air distribution and therefore hotspots when the set point was any higher than that.
After a haggling period, I managed to get the client to agree with a 70 degree set point. The system maintains that temperature with no hot spots, however IT people are set in their ways and the room is maintained at 67F and 50%.
A humid climate, however a pressurized space with a big internal sensible load. So 68 at 50% is not impossible, but 68F @ 40% is not happening in the summer time.
RE: Help With Liebert 3000 Unit
Digital R. humidity is expensive to measure accurately; 3% is your typical RH sensor, with a big cost jump to 2%. Trust the instruments accordingly.
RE: Help With Liebert 3000 Unit