Onix Tubing Installation Manual

Watts Radiant: Onix Installation Manual page 17
increase or change, variances in the
heating system will result.
Onix Spacing
Onix is generally installed 8 inches on
center, to the underside of the subfloor
for a Staple-Up or a sandwich applica-
tion. Closer spacing may be used in
areas of high heat loss, such as an
exposed wall with a high percentage
of glass. Higher tubing densities, up to
4 inches on center, may also be used in
areas that have a low thermal conduc-
tivity, such as areas with thicker than
normal subfloor or dense carpet and
pad.
It is important to note that simply dou-
bling the amount of tubing does not
double the floor s heating output. The
floor s ability to deliver heat to a room
is based on the floor surface tempera-
ture. The amount of radiant tubing and
the fluid temperature controls this sur-
face temperature.
For most rooms, a standard 8" spacing
will be more than adequate, with some
4" perimeter banding. In a few cases,
where supply fluid temperature is lim-
ited, an entire room may be installed at
a close 4" on center spacing. This may
be seen in a sunroom or remodel con-
dition, where the floor covering and/or
high heat loss requires tighter spacing.
Watts Radiant s RadiantWorks design
software generates a specific
Nomograph for each room in the
design. Nomographs are charts that
convey several key factors associated
with a room, such as tube spacing,
floor surface temperature, floor heat-
ing intensity, mean (average) supply
water temperature and back and edge
loss values. Nomographs are essential
Sup
Sup
ply
ply
/Return Man
an
ifol
ol
ds
ds
Floor
or
Cov
Cov
er
er
ing
ng
Upp
Upp
er
er
Sub
Sub
floor
loor
Sub
Sub
floor
loor
Oni
ni
x
Jois
ois
t
Foil
oil
Fa
Fa
ced
d
Insulation
on
Sl
Sl
eep
ep
er
er
to any radiant design. More informa-
tion on how to read and use a
Nomograph can be found in the
Appendix.
Perimeter Banding
Four, five or six inch Onix spacing is
frequently used along outside perime-
ter walls. These high-density areas are
called perimeter bands and tubing is
generally spaced half the main spac-
ing. Banded areas range in width from
two to eight feet, with the wider bands
generally used in front of taller
exposed walls with a high percentage
of glass. A good rule of thumb is to
use a perimeter band width of 50% to
70% of the height of the wall. Most
banded widths will be 4 ft., or three
joist cavities.
For example, in a home with 8" spac-
ing in the main floor area, a 6’ 8" high
patio door would have radiant tubing
on 4" centers a minimum of 40" in
front of the door. This would corre-
spond to double-spacing in the first
three joist cavities. If possible, keep
the number of Onix runs per joist bay
an even number, either two or four.
This will help keep installation time to
a minimum.
For sandwich applications the same
general guidelines are applied. Eight
inch sleeper spacing is used for eight
inch tube spacing.
4” o.c. Onix spacing
for a distance of half
the wall height.
8” Onix Spacing
Banding Areas.
Onix is often installed at closer spacings at the perimeter of exterior rooms to improve comfort.
Frame Floors