Onix Tubing Installation Manual

Watts Radiant: Onix Installation Manual page 23
Caution: DO NOT over tighten the
clamps. Over tightening may cause
an improper fit.
For detailed information on the proper
steps to conducting a pressure test,
refer to the Appendix of the installa-
tion manual.
Insulation Details
Insulation is one of the most critical
factors that can drastically affect how
a system operates and performs.
Different conditions call for different
insulation requirements. Insulation
should be a minimum of 3-1/2" or R-
13 foil-faced fiberglass batt when the
radiant floor is installed over a heated
space, such as a basement. 5-1/2" or
R-19 foil-faced batts (or thicker,
depending on the climate) should be
used when the area below the radiant
floor is unheated or exposed to the ele-
ments.
Caution: you must insulate the exte-
rior band joists with the same type
of foil-faced insulation to prevent
any excess heat loss directly to the
outside.
The design calculations used in
RadiantWorks are based on foil-faced
insulation. If a non-foil-faced insula-
tion is used, the performance of the
radiant system will be reduced by as
much as 25%.
Foil-faced batt insulation is preferred,
but a foil-faced, high temperature
board insulation, such as a polyisocya-
nurate or an extruded polystyrene, may
be used. Make sure a proper thickness
to R-value board is selected to provide
the required minimum R-value for the
project. To ensure proper performance
from a board insulation, make sure the
board creates a completely airtight
cavity. Use foam sealants as needed to
seal all air gaps.
The use of foil only, or the use of a
foil-faced bubble pack insulation is
not recommended by Watts Radiant.
These products should only be used in
conjunction with another type of insu-
lation, such as a non-foil-faced batt or
a blown-in insulation. Use of these
methods should only be considered by
professional installers who have had
prior successful experience with these
types of products and/or applications.
Special Joist Construction
As building technologies change, more
and more projects are using TJI joists
and open web trusses. These specially
engineered building joists allow for
greater loads and broader spans for
larger construction needs. Although
they may solve some of the construc-
tion issues, they do raise some chal-
lenges for a proper radiant floor instal-
lation.
TJI Joists
TJI (Truss Joist International) flooring
systems are installed in a similar man-
ner as conventional joists. The design
of a TJI joist system is slightly differ-
ent, consisting of a laminated core
material that resembles an I-beam.
Due to this design, the allowable space
between the two center supports is
slightly wider than what would be
seen in a conventional 16" oc joist sys-
tem. A wider batt insulation is required
to fill this space, typically a 19" wide
batt is required. The remaining instal-
lation details described earlier should
be followed.
Note: Heat is often lost from a joist
bay through holes drilled for plumb-
ing and electrical lines. To prevent
this, install foam spray insulation
in these holes.
Open Web Trusses
Cross bracing is applied to two main
header beams to form a W style pro-
file. This design allows for easy instal-
lation of radiant tubing and other com-
ponents such as electrical and plumb-
ing. However, since a tight joist cavity
is desirable, some previously discusses
guidelines need to be adjusted.
Air movement in a joist bay can be a
problem with radiant heat installations.
Reduced radiant floor output is associ-
ated with air movement from joist bay
to joist bay or from joist bay to the
outside. In a conventional joist system,
air movement is isolated to a single
bay. This is not the case with an open
web system.
Onix
Insulation
Always install vertical
insulation at exterior walls.
Foil-faced batt insulation
R-13 to R-19 insulation is typical, depending on applica-
tion and construction conditions. More may be needed.
2”-4” Air Gap
Staple-Up