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Old 08-23-13, 05:17 AM   #16
Mikesolar
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Quote:
Originally Posted by Minimac View Post
It's not the only issue, but its conductivity is the issue here. I stated it's not very efficient. But, I agree that for HEATING in concrete, it works. Concrete will erode most metals rather quickly, unless it is properly encased. The question posed by the O.P. however involved it's use for cooling in the area where his ductwork will run. He also stated that the first floor concrete is already heated.
Unless he is prepared to encase the pex in something to serve as a heatsink to transfer the "coolness", I don't see it being of any meaningful value with regards to cooling. Just running Pex in a dead air space, even with additional controls, monitors, pumps and fans and what ever else you can think of, will provide little, if any practical cooling. Of course copper,aluminum, steel( all much better conductors) or any other piping won't do it either without a lot of extras.
The idea of "radiant cooling" is a good one, but I'm reminded of a picture I saw, the redneck air conditioner. A fan ducted into a cooler filled with ice, ducted into the room. How's that for bragging rights?
I've been called in to fix copper radiant tubing in 60 year old concrete floors and it is not fun when you have to tell the owner that it is not worth fixing. The will need an overpour of gypcrete and new tubes. Given the amount of galvanic corrosion I have seen over the years, I am really reluctant to have copper in contact with aluminum for any period of time. I just had to remove a copper sensor well from a 5 year old SS tank because the copper had corroded through. It had a small piece of steel inside to push the sensor to the tube wall.

Anyway, in the end, it is all about measurement and controls.
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