[Greenbuilding] PEX location in concrete slab

[Speireag Alden]

Sgrìobh Chris Green:

>I am now wondering if the aluminum on the top of the foil covered 
>under-slab insul  might be functioning as a heat sink, drawing the 
>heat from the warmer regions under the PEX to the less warm areas 
>between the runs, and thereby helping to 'average out' the 
>concentrations of heat a bit?

     It is certainly doing that to some extent, but I doubt that the 
effect is measurable, and I strongly doubt that it's perceptible.

     The rebar, on the other hand, being right up against the pipe, 
reasonably thick in comparison to the foil, and criss-crossing all 
over the place, is probably doing a dandy job of helping distribute 
the heat.

     I know that a radiant floor will have hotter and colder spots, 
because I've felt them in mine.  However, I have only felt them when 
looking for them with my hand.  I have never noticed them just 
walking around barefoot, except right at the start of the season, 
when the slab is coming up to temperature.  Certainly I've never felt 
them in socks or shoes.

     My floor is rarely actually perceptibly warm at all, even with 
the heat running.  It's just not cold.  An efficient house should 
never require so much heat that the floor can get warm enough to be 
noticed specifically.  The whole house just gradually warms up, and 
unless you investigate, you don't notice the source.

     If I had it to do over again, there are things I would do 
differently, but I would not spend any extra effort or money trying 
to even out the perceived floor temp.

-Speireag.

-- 
Leaves starting to turn
Anticipation shivers
Me as winter comes

-Speireag.