shows the floor design. Floor insulation, floor
coverings, floor load bearing characteristics, and
manifold access panel should be coordinated with the
architect and structural engineer. The method of
insulating the floor is different from typical
construction. If the insulation is not properly
designed, the system will not work.
The drawings should also address the desired control
sequence for the radiant heating system. The
drawings should indicate which loops will require
temperature control, in order for the manufacturer
to provide a proper manifold. Various control
strategies can be found in HYI 400 and the RPA
standard guideline for the Design and Installation
of Residential Radiant Panel Heating Systems. The
control sequence should consider the required
circulation of water through the boiler. High mass
radiant floor heating systems do not typically
respond quickly to a change in load due to the
thermal mass of the floor. Therefore, night setback
control is not feasible for high mass floor radiant
heating systems, unless long durations of unoccupied
spaces occur such as in a chapel.
Radiant floor heating systems use lower water
temperatures than standard convection heating.
Therefore, the boiler may experience a water
temperature that is lower than recommended by the
boiler manufacturer. If this occurs due to the
design and selection of boiler, a mixing valve or
other control devices should be provided to maintain
the recommended water temperature for the boiler.
Several floor designs can be used for radiant
heating. The following examples indicate a few
possibilities:
Slab-on-grade: typical concrete floor system with
tubing imbedded in concrete.
Thin-slab system: tubing imbedded in a thin light
weight concrete on top of a wooden sub-floor.
Above floor plate system: tubing installed in
channels with reflective metal barriers above a
wooden sub-floor. The tubing is then covered with
thin sheets of plywood.
Below floor plate system: the tubing is installed
below the wooden sub-floor using reflective metal
barriers.
Below floor suspended tube system: the tubing is
suspended within the interstitial space between a
wooden sub-floor and insulation. (Seldom used due
to higher water temperature requirements).
Below floor staple-up system:
the tubing is stapled
SECTION 15569A
Page 36
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