We monitor various data from our 4 In-Row Coolers, recently the "HOT GAS BYPASS" valves have been edging closer to 100%
Does this indicate anything?
A couple of years ago we had one unit that was stuck at 100%.
Hello. The hot gas bypass opening would not by itself cause any alarm to the unit. The hot gas bypass is used by the units in low load situations to protect the compressor from slugging. If you are in the northern hemisphere and winter is approaching, the load will usually go down slightly due to it being colder outside. This would cause the hot gas bypass to open up more to protect the compressor. If you would like to attach the data logs on the unit(s) we can take a look at them and make sure the pressures and temperatures look good.
It is getting colder, but the "Monitoring" has been the same thresholds for ~3 years and only this year does it seem to be creating many more alerts.
what's the easiest way to export the group data logs?
Hello. The Best way to get the full logs is to perform a Get data.txt through ftp. You can also copy them off the web interface.
Uploaded, not sure if it includes all group data.
Hello. From the data logs the Hot Gas Bypass is opening because of a low load in the room. The unit is only seeing between 2.7-4 kw of load. This is very close the the minimal load the unit can handle. The Hot Gas Bypass is opening to allow the unit to run at these low loads and protect the compressor. This is normal operation for this unit at those loads. The data in the rest of the logs all look good. The pressures and temps are all in normal ranges. It is just the low load causing the Hot Gas to open.
So which temperature sensor is the most important one to monitor? we have 10 racks ( 2 with a Symmetra UPS ) but only 4 equipment racks with sensors flipped to the cold side doors?
Hello. This does depend on the setup and environment of the room. Generally the main one to look at is the rack inlet sensor as the main goal of the cooling unit is to provide cool air to the intake of your servers. You will have to be careful that the sensors are not picking up the heat from the servers or any other heat sources that may give higher readings then what the intake air actually is.
Where is the rack inlet located?
If we try to put the system in into 3+1 rather than 4 active the temperature creeps up.
It's presently set in "HACS" is that best, I know it's difficult t comment without seeing the layout of the Isle and the specific heat loading in each cabinet.
Hello. The rack inlet sensor should be placed on the front of the rack next to the cooling unit. It is a 13 foot sensor that usually comes out of the top of the cooling unit and is placed on the front door of the rack next to the unit. It is a black wire with a rubber tip on the end. In HACS mode the unit will not be using the rack inlet sensor to determine if it needs to cool. In HACS the unit will use the return and supply air temperatures to determine if it needs to cool. It is hard to say if this is the best setup for your room. Do you have a HACS containment system in your data center?
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