Quote:
Originally Posted by Exeric
...on my system with with two wood layers before floor covering you just might be able engineer one system that accepts the two insulation values of say R=2.7 (3*0.9 wood floor layers) and R=4.3 ((2*0.9) + 2.5 a single carpet layer with 2 wood layers.) That is a difference ratio of insulation values of about 1.6...
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Difference ratio of 1.6?
Are you inventing a new kind of math here?
If you have just gone from R-2.7 to R-4.3, you have just increased the thermal resistance of your floor covering by 59.3%... and you still want carpet and carpet padding on top of that?
Above is a temperature chart for a product called QuickTrax, which I do not think is anything special, but it does illustrate what we are talking about.
The diagonal lines are there to help you calculate how much you will have to raise your feed water temperature to compensate for the insulating effects of various floor coverings. And if you install your PEX below the subfloor, the subfloor becomes part of the chain of insulation.
Floor covering makes a very big difference in the temperature of the feed water required to supply a given number of BTUs per hour.
When you increase the insulating effect of floor coverings, your boiler is going to have to work harder to overcome that thermal resistance... and your wallet is going to have to work harder to feed your boiler.
And this is exactly why we are so interested in high-efficiency, low temperature heating.
You should check out the link to Vlad's DIY radiant floor install, he did a great, innovative job. It must be said too, that he also did a highly effective job of building a very tight, well insulated house that holds in the heat that his floors produce. The value of reduced infiltration and superior insulation can't be overstated.
(
NOTE TO VLAD: I still think you need to insulate your crawlspace.)
Best,
-AC