(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

[furzicle.livejournal.com]

Check out some books from the library on passive solar heating. The best and most energy efficient way to utilise water cooling would probably be to circulate it to the cool spaces underground (below the "permafrost"!)and then up into the household. Water retains its temperature longer than air, and the earth longer than water.

[sfllaw.livejournal.com]

You can pump cold water through radiators, but they won't radiate cold. You'll have to force air through the fins to circulate it around.

Also, beware that humidity will condense from the radiators and pipes, so you'll have to find some way to deal with that. Otherwise, you'll ruin your floors and walls.

[rebbyribs.livejournal.com]

surpheon would be the perfect person to ask this question to. (He designs HVAC systems for green buildings.)

[bom.livejournal.com]

Sure you can. It's what air conditioning does, only AC uses a fan over the radiator and Freon instead of water.

On a somewhat related thread, I thought of using the cold water line for the toilet in my bathroom to dehumidify the room. Basically, I'd just extend the water line using 30 feet of copper tubing with a drip pan underneath. I have more or less decided not to do it since the water would warm up quickly unless the toilet was flushed a lot and the system probably wouldn't remove much water.

[wanton-adonis.livejournal.com]

they used to run water over something like that(open to air I believe) in FL and from that devised the concept of refrigerators....so I'm sure if you could circulate it fast enough with good contact to air...without it picking up too much friction.....it works....(James Burke Connections).....really old desert houses used to have walls of water for cooling......personally I prefer hoses

[anemone.livejournal.com]

As a matter of fact, radiators don't radiate much heat. They are mostly convective heaters. Or so says my HVAC engineering source.

[(Anonymous)]

Short answer, yes, but you probably won't get much cooling.

All 'radiators' in homes depend more on convective heat transfer than radiative, that is they create a thermal updraft that draws air over the hot surface to be heated. Radiation is usually at most a third (more likely about 10%) of their heat transfer.

The effectiveness of convectors is dependent on the difference between the air temperature and the surface temperature. In heating, a temperature of 140F to 160F is common, for a delta between room and 'radiator' surface temperature of 70-90F. In cooling, the lowest temp you can go is 60F-50F (in Oakland area) due to concerns about condensation, for a delta T of only 10-20F. The convective capacity is killed by the low delta T.

Radiant heating and cooling is all about surface area, and lots of it. Covering the ceiling is a common approach, and the last conference room I did used about 50% ceiling and 100% floor (tubing in a concrete slab) radiant surface, with active monitoring of space dewpoint to pre-empt condensation (this is probably a bit of overkill, but conference rooms are murder to do radiantly due to all the people who insist on spewing out humidity while in them).

Going back to the short answer, you won't get much cooling but you will indeed get some. With a very careful building design and low occupant expectations (particularly if occupants don't have to conform to a no-shorts-and-wear-a-tie dress code), you may get enough. You'd really need to maximize the radiative area though.