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re: radiant heat
2 dec 1997
wrote:
>...any carpeting above the heated floor increases the lag time.
let us eggsplore zees matter of carpeting lag time: zuppose zee
temperatoor of our 70 f 8' cubical room with a 90 f floor and 1/2"
drywall and thermal capacitance of 160 btu/f is zuddenly dropped
to 60 f by some sort of indoor mini-ice-age anomoly...
the effective thermal resistance from floor to walls might consist
of the floor convection resistance of approximately r2/3/64ft^2
in series with the wall convection resistance of r2/3/320, a total
of 0.0125 f-h/btu, so the time constant rc = 2 hours, and the room
might re-warm to 70 f in such a way that 70 = 90-(90-60)exp(-t/2) when
20/30 = exp(-t/2) or t = 0.8 hours or 49 minutes. a 1/2" rug over the
floor might increase its r-value by 1.5, so r = 0.036 f-h/btu and
rc = 5.7 hours and t = 2.3 hours...
nick
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