(no subject)

[nibot]

This is sort of a physics question: Could you pump cold water through radiators to cool your house? The obvious flaw is something like "cold doesn't radiate," but, then, don't we have the general principle that a good antenna for transmission is usually a good receiving antenna too, and hence the cold "radiator" should absorb thermal radiation from other objects? (In addition to cooling by convection.)

Comments

[surpheon.livejournal.com]

Yup, and the water that runs through the fan coils is then cooled by big ass 'chillers' that cool water using a standard vapor compression cycle. As a side note, water is a miracle liquid for cooling. It's heat capacity is amazing, and its phase change is a fundamental part of every large system in the form of cooling towers. The chillers evaporate water directly to the air to dump heat at a rate of almost 1000 Btus/lb of water evaporated. 1000 Btus is enough to bring a quart and a half of water to 210F (note that going from 210F to a vapor at 213F would take over 6000 additional btus - phase changes take energy!).

The T-stat usually controls the valve on the coil rather than the fan because small variable speed fans are pricy, but thats a minor quibble. And cheaper variable speed fans are in the pipeline (which is cool, because reducing air flow rather than liquid flow through the coil would save more energy - pumping air is more turbulent and inefficient).