expansion tank overflow

[evilampire]

Hi,

I've been working at a data center wherein the configuration is n+1, which means there's always a back up in (acmv, electrical systems) in case any power failure.

Our current configuration for acmv is air cooled chillers with a back up of watercooleed. The water cooled side was not running for about three years & lately we tried to run only the chilled water pumps. Due to this we've been encountering expansion tank overflow when we run the chilled water pumps while the air cooled chillers are in operation. (water cooled chiller are not running).

We tried to check if there were open interconnecting valves between air cooled & water cooled but there was none & everytime we run the chilled water pump on water cooled side, we experience overflow of expansion tank.

I hope someone can help me what is the probable cause of this?

[install monkey]

tank should feed on the inlet to the pump( negative side) to maintain a positive inlet pressure
also check all gate valves are open

[aramis]

I've been working at a data center wherein the configuration is n+1…Bla Bla Bla … not running for about three years …

Please, go tell the guy in charge to drop the “+1” unless he is willing to start this system at least once a month!

Did you measure the pressures and pressure losses of the water side?

Without this and at least a schematic that includes all the valves, it is impossible to guess the reason.