Radiant Slab Comments
To the Editor:
I have some comments on
"Radiant Slab Techniques" (8/92).
The author explains that if different
slab areas are covered with materials
having significantly different
thermal resistance, additional
mixing valves are required. This is
not a must, because the floor surface
temperature, and thus the energy
output, may also be controlled by
varying the hose spacing.
Regarding oxygen-diffusion
barrier hose, only about 20% of the
oxygen content in a hydronic circuit
can be directly attributed to the
oxygen permeation through a "nonbarrier"
tube. Sources of oxygen
ingress include a failed or undersized
diaphragm expansion tank, loose
pump flange gaskets, and micro air
leaks at screwed/compression joints,
etc. The German Standard DIN
4726 states two more ways of
dealing with corrosion,