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Posted by d on June 1, 2006, 4:47 pm
Hi all,

I have an idea about using interior frame walls as radiant panels and could
use the groups input.

The design would consist of running a hydronic heating loop through interior
frame wall(between the studs) and then infilling the cavity with stabilized
earth(dirt + cement) before sheeting.

Some advantages I see are;

-Panel fulfills multiple purposes, that of an interior wall, providing
thermal mass, and acting as a radiant heating panel, and would not differ in
appearance from other standard walls.

-Panel used in conjuntion with SHW systems, heat pumps, or conventional
boilers, to provide more efficient, comfortable, and stable heat than air
based systems.

-Panel adds thermal mass to the buildings interior softening fluctuations in
heating inputs

-Panel enables the incorporation of radiant hydronic heating into existing
housing without having to pour new slabs or limiting floor covering choices.

-Only additional materials required, other than for a standard wall, would
be the hydronic tubing and cement, making it economical compared to other

Some disadvantages would be;
-Vulnerability of tubing to puncture
-Lower responsiveness

I'd welcome any comments expecially from the seasoned designers and
installers out there.

Darren Hatina

Posted by Ecnerwal on June 1, 2006, 9:47 pm

More than the usual thermal gradient. Your standard baseboard/radiator
type arrangement is run around the outside walls - while this means more
heat is lost through the walls, it also means that the room is somewhat
evenly heated. Radiant floor at least reaches to the outside wall, and
is often spaced more closely near it for a bit more heat there. With
this system, you'll get a "cold outside wall - hot inside wall" effect.
This might prove uncomfortable.

Depending on the structure, supporting the weight of this wall. Quite
feasible with proper design, but since you are approaching it as a
retrofit idea, the existing structure might be offended by the weight.

Incorporation of wiring in this wall will need to be pre-planned and
done in conduit, or done with surface-mount conduit.

Filling the wall might be a bit of a challenge at best.

Cats, coffee, chocolate...vices to live by

Posted by d on June 2, 2006, 7:22 am
 I agree with you on the wiring and structural side.

The specific application in my own home is in a walkout basement where the
wiring is dropped from the floor joists above and the wall sits directly on
the basement slab so I don't suspect either of those will be a problem but I
will be checking with a structural engineering friend about load
considerations for slabs and suspended floors.

It will be hard to know about the comfort part until I try it, but I think
theres some truth in putting radiators on outside walls to avoid cold
drafts.  I don't know how effective forced air systems are at heating
outside walls either though.

For filling up the cavities, I guess I could put the lower drywall sheets on
first and use them as a form left in situ and maybe building up from there
with form ply.  Heck I could also remove the wall entirely and build a cob
wall instead using the same concept.  I could get some nice curves that way

for a  4'x8' wall section framed with 2x4's there would be over 10cubic feet
of mass.  I wonder how much heat that could store?

Thanks for the input Ecnerwal

Posted by Ecnerwal on June 2, 2006, 12:39 pm

Not drafts - cold walls. Drafts are a separate problem, and are
addressed by caulking and sealing. A perfectly caulked and sealed
exterior wall will still be cool to cold (extent depending on
insulation, outside temperature, etc.)  

A: search for past posts where Nick Pine has mentioned the thermal
capacity of masonry (which is much lower than water).

B: wait for Nick to post a reply. If B takes too long for you, A works
well, and is generally faster than looking it up elsewhere, though that
would constitute option C:

Nick has a scheme of putting sealed pipes full of water in the wall
which would give you a lot more thermal mass and easier installation
than a masonry fill. If time is worth anything, double 5/8" drywall will
also give you thermal mass with a simple, speedy construction method -
the space can be reclaimed on a non-load-bearing wall by using skinny

Panel systems which can be made or purchased will allow mounting radiant
tubing on the face of an existing wall without bulking it out too much
(an inch or so for panel with grooves and drywall to cover). Or, since
you mentioned cob, you could make a cob wainscot that grows into window
seat as appropriate to run around the outside wall and contain the
radiant tubing...

I agree that on a slab the weight should not be an issue.

Cats, coffee, chocolate...vices to live by

Posted by nicksanspam on June 2, 2006, 2:36 pm

... 0.16 Btu/F-lb, vs 1 for water, or 25 vs 62 Btu/F-ft^3. Picture pouring
concrete into a wall cavity until the lower drywall explodes, at 100 psf?

Not my scheme, but one paper described 3(?) 4" thinwall PVC pipes in each
2x6 interior wall stud cavity. With holes at the top and bottom, they
could store and distribute heat and coolth for a house. It looks like our
Rochester proj will have overhead pipes under a low-e ceiling to store and
distribute more heat at a higher temp with good room temp control, using
a slow ceiling fan and a room air thermostat and an occupancy sensor.


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