Re: [SAGE] Greener Machine Rooms: Cooling?

[Richard Chycoski <rskiadmin@chycoski.com>]

Allan West wrote:
> 
> This week we've started on duct sizing, which is less relevant to
> machine rooms since most shops use raised floors to distribute cool air.
> If you build a machine room and have control over the duct/plenum/floor
> height, larger is better. It allows more capacity growth for the future
> and less strain on the fan at every level. Our physics machine room now
> has spot coolers and overhead ducts because the 9-inch raised floor is
> not raised enough to accommodate the current load.

Raising the floor higher does have it's limits - weight becomes an issue when 
the floor is too tall. Beware that you don't exceed the load limits when you 
raise your floor.

My previous place of work had a floor with about 40" of clearance - you could 
(and we did :-) crawl around under the floor to cable the room. However, some 
equipment (like the IBM 370/155 mainframe) was so heavy that extra struts had 
to be placed at the midpoint on each tile. Modern, densely-packed racks have 
similar weight loading problems.

If you have more typical underfloor clearance, you need to also be concerned 
about what else is under the floor - the cables and pipes. You need to make 
sure that your airflow is not being blocked. This was worse in 
mainframe/serial port days when the bulk of cables between racks was *huge* 
(ever seen IBM channel cables, or connected a few hundred serial ports between 
two rows of racks? :-), but you still have some big power cables, bundles of 
network cables, and pipes under the floor to obstruct the flow. Clear out 
unused cables under the floor, and watch the routing of cables to prevent hot 
spots in your room.

- Richard