Underfloor Radiant Heat Systems
Heat Transfer Plate Pricing
Our Heat Transfer Plates are Made
in the USA!
Notice how the Heat
Transfer Plates are shaped to fit the perimeter of the tubing. Heat transferred
from the tubing to the trough portion of the heat transfer plate conducts out along
the “wings” of the plate. Because aluminum is an excellent heat
conductor, these relatively thin plates can disperse across the floor
almost as well as a slab yet at a tiny fraction of the weight and only
about 1/2 the added floor height of a thin-slab. They are a versatile
component both for floor heating systems as well as radiant walls and
Above Floor Tube &
the tubing and plates are located on the top side of the floor deck. The
tubing can be run in virtually any direction. The system can be adapted
to several types of finish flooring, and is particularly well suited for
nailed down wood floor installations.
Begin by fastening 5/8” -
3/4” plywood or oriented strand board (OSB) “sleepers” to the floor. The
sleepers are placed to create 3/4” wide grooves into which the tubing
and trough portion of the plates are recessed. To minimize any squeaks,
the sleepers should be glued as well as nailed (or screwed) to the
Grooves for the return
bends, as well as other curved tubing paths can be formed by routering
out the 3/4” plywood or OSB. Another way is to place triangular shaped
spacers to support the secondary floor layer at curved areas.
plates are set into the grooves with ends spaced about 1” apart.
Pull each plate against one edge of the sleeper and tack it in place
with two or three light gauge staples on the same side (and only on this
side). This allows the plate to expand as the tubing is pushed into it
as well as when the plate heats and cools.
Then tubing is laid out and
pushed into the grooves in the plates. Stepping on the tube as it aligns
with the grooves ensures it is pushed all the way into the groove.
It is NOT necessary to
install silicone caulking into the troughs of the plates when installing
Kitec XPA pipe.
floor tube and plate systems are ideal when nailed-down wood flooring
will be installed. The flooring can be placed directly over the tube and
plates without needing an additional cover sheet. The flooring should be
installed with its long dimension perpendicular to the tubing. Nails can
be driven through the heat transfer plates, through the sleepers and
into the subfloor. Be careful not to drive nails through the tubing on
return bends or other areas when the tubing is not visible as the
flooring is laid. If the tubing needs to run parallel to the flooring at
times, it is best to drill a shallow hole through the subfloor and route
the tubing through the floor framing where it is protected against nail
punctures. The tubing can also be “plunged” beneath the subfloor and
then routed up through the bottom plate of a partition to connect to the
For other types of
flooring, it is necessary to install a thin 1/4” or 3/8” cover sheet
over the tube and plates to serve as a smooth stable substrate. Plywood
is often used as the cover sheet under vinyl flooring or carpet. Cement
board has also been used under ceramic tile. All tubing circuits should
be pressure tested prior to installing the cover sheet. The tubing
should remain pressurized as the cover sheet is installed. Be careful
not to drive fasteners through the tubing when securing the cover sheet.
The same concept of the
sleeper system can be used in low heat load installations, but without
the heat transfer plates—mostly for floor warming systems.
The wood structure is a
poor conductor of heat so there is limited heat transfer sideways. The
relatively thin layer directly above the pipe will allow a lot more heat
through than sideways. This results in large local temperature
differences depending on the position of the pipe. This effect limits
the amount of heat that can be transferred without creating high
temperature “lines” on the floor surface.
The spacing used should be
6”-8” and again only a limited amount of heat output can be provided. To
overcome this limitation, some manufacturers produce pre-routed plywood
sheets with aluminum layer attached to it to improve sideways transfer.
Floor Tube & Plate Systems
It’s also possible to
fasten the tubing and aluminum heat dispersion plates against the bottom
of the subfloor. Below floor tube and plate systems work well when
raising the floor level is not an option.
The plate cradles the
tubing against the subfloor as well as disperses the heat across the
floor to avoid objectionable variations in floor surface temperatures.
The ideal installation
conditions for this system would be completely unobstructed floor joist
cavities. However this is often not what the installer has to deal with.
In some cases, plumbing, electrical, ducting or other utilities may
already be routed through the joist cavities. This could make access to
the underside of the subfloor difficult or even impossible.
Always inspect the
underside of the floor deck before committing to a below floor tube &
plate installation method.
Radiant Heat Information