cooling systems

Faced with the prospect once again of significantly higher energy prices coming to our region, we want to start to look at better and more efficient ways to cool our colocation facility. Right now we have several ton of traditional air conditioning units sucking up electricity like its free. As winter is approaching, surely there must be some computer safe way to take advantage of all that cold outside to help contain our energy costs, not to mention be a little more environmentally friendly. We were thinking we could circulate the air up to the roof and cool it there inside some aluminum ducts and then bring it back down. We dont want to just bring in cold air as it is quite dirty outside since we are next to a major highway. Anyone done anything like this before in a computer room setting ?


google search for "air to air heat exchanger" - there are many
companies that make products that do exactly what you want.


Mike Tancsa <> writes:

The R2000 houses have a heat exchanger to recover heat from the air that
is being expelled from the house. Maybe the same device just running in


There are indoor units that have multiple coil sets.
One can be utilized for mechanical cooling, the other
can be used for "free cooling" mechanisms.

For example, a water loop can be implemented
that rejects its heat via a roof-top evaporative tower.
(e.g. the big BAC boxes you see "steaming" occasionally on roof tops
or behind buildings).

As long as it is cold enough outside, you might
benefit from this.

A large office complex I used to work in actually took this
a step further. The waste heat from the computer rooms
was used year round for building environmental purposes.
It was used as first-stage heating in the winter.
And in the summer, it was used as "re-heat", so that the
building could offer effective dehumidification.

(conventional re-heat using utility energy is poo pooed
these days, because of the desire to conserve energy;
this is why so many office buildings seem to be
dank in the summer, not enough heat load to support
the cooling needed to remove the moisture and re-heat is prohibited)

If the indoor units you presently have rely on external
mechanical cooling (chillers located somewhere else),
then you may be able to have only the central chiller
system "plumbing" modified to provide the "free cooling" capability.
This would save the cost of changing-out the indoor units.

Utilizing direct outside air is likely unacceptable.
Even if you could filter it, it would be difficult to humidify.

Schemes that involve running indoor air through air-to-air heat exchangers
may become problematic if the outdoor air is very cold.
You must take care not to inadvertently dehumidify your indoor air excessively.
Also, you'll need to provide drainage for the air-air heat exchanger,
and make sure you don't get condensation in the downstream ducting
(a real pain in the GeorgeW, potentially leading to microbial growth, etc)

Good luck Mr. Phelps.

Depending on the type of AC you have, it may already do that. If it is, say,
a one piece roof mounted unit, with intake/oulet ducts attached to the
building, then just leave the fan on all the time and it will do what you

If it's a split unit, with copper tubeing bringing the freon from an outside
to inside unit, then this doesn't work.