Headmaster valve in comms room

[acnerd]

Hey guys, just a quick question on a headmaster valve please:

I understand that they are used for low ambient head pressure control ..... but today I came across them in a Uniflair upflow close-control cabinet (Italian make), used in comms/computer server rooms. 2 fridge circuits (R407c) in the cabinet and water-cooled condensers. The headmaster valve is within the cabinets in the room.

I am sure I am missing something here; why would I want to control head pressure based on inside room temperature?

Thanks

[joe magee]

A headmaster maintains a constant head pressure regardless of ambient temp. It doesn't matter what the condensing medium is ex: water, air etc. Now for your next? If it's cold outside and warm inside that computer room and you had no way to control your head pressure you would start to stack refrigerant in the condenser resulting in a starving evap coil. Different manufactures control head pressure various ways, some use fan staging others will use a receiver with a headmaster and others will use a combination of both. On a five fan condenser I had a drive on the first fan with fan staging on ambient stats and a headmaster with a receiver. Go figure.

[apac1]

the headmaster in the systems are nessecary for the bigg change in water tempetures in the drycooler fluid system ,at freecooling the water temp will be 8 C in winter ,insummer the water tempeture will be 28 - 40 C.

mayby there is also a 3 way valve in the unit white energie saving coil in the unit,the carel regelation will open the 3 way valve if there is enaf differance between air temp and fluid temp .
the fluid will nou first go two the engery saving coil and then tru the plate exchangers .

gr peter