Install Instructions

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IM-PR 566442 1114 (Design Manual)
(CSA B214 Clause 14.2.1)
Floor surface temperatures shall not exceed
(a) 25°C (77°F) in areas where prolonged
foot contact with the oor is likely;
(b) 31°C (88°F) in dwellings or commercial
space;
(c) 33°C (91°F) in bathrooms, indoor
swimming pools and foyers; and
(d) 35°C (95°F) in radiant panel perimeter
areas, i.e., up to 0.8 m (2.5 ft) from
outside walls.
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5. ©CSA Group, B214-12. 2012. “Installation Code for Hydronic Heating Systems” Clause 14.2.1
If a targeted surface temperature exceeds these
recommended limits, then consider reducing the
heat load of the space by installing extra insulation
and/or supply supplemental radiant panels for
the space (e.g., walls, fan coils or radiators), or as
otherwise specified by local governing bodies. For
CSA requirements see Section 1.6.2.
1.6.2 Floor surface temperatures
1.6.3 Supply water temperature
Required supply water temperature varies based
on the heat load of the space, the tubing spacing
and size, and the materials used in the heated
assembly. To identify the required supply water
temperature, use the figures in Appendix H, based
on the assembly type, or use Viega’s Radiant
Wizard. The figure in Appendix H requires you to
know the R-value of the finished assembly located
on the conditioned side of the radiant panel.
R-values for typical materials (e.g., carpet, gypsum,
tile, wood flooring, etc.) may be found in Appendix G.
Options that can lower the required supply
temperature include:
• Selecting a covering with a lower R-value
• Decreasing the on-center spacing of tubing
• Increasing flow rate
• Increasing insulation on the unconditioned
side of the radiant panel
By doing the opposite of any of these options, the
required supply temperature is increased.
Maximum supply water temperatures are a function
of the tubing and tubing enclosure/covering. For
ViegaPEX Barrier and FostaPEX tubing, the supply
water temperature should never exceed 180°F. This
supply water temperature is typically only reached
in baseboard heating applications. For radiant floor
heating applications, do not exceed the following
supply temperatures:
• Thin-slab, gypsum-based products: 140°F
• Tile, stone or marble: 140°F
• Concrete: 150°F
• Contact flooring manufacturers for maximum
supply water temperatures based on the
application, which may be affected based on
the type of adhesive used.
Remember, for all flooring applications, do not
exceed a surface temperature of 85°F. In order to
achieve a design supply temperature that is lower
than that provided by the heat source, see Section
1.12, Controlling the system, for mixing options.
1.6.4 Temperature drop
The design temperature drop across the primary
loop should be made with consideration given
to heating source type (e.g., condensing or non-
condensing boiler, ground source heat pump,
etc.), first costs of the distribution system, and
energy use of the system. Traditionally, a design
temperature drop of 20°F has been selected across
indoor circuits as a good balance between flow
rate, tubing diameter and pump sizing.
Potential effects of increasing the temperature
drop beyond 20°F include the ability to reduce flow
rates, piping diameter and circulator size. System
efficiency may also be increased by specifying a
smaller, lower-power circulator. If the heat source
is a condensing boiler or ground source heat pump,
lower return water temperatures can increase the
operating efficiency of the heat source.
Potential negative outcomes of increasing the
temperature drop of the primary loop beyond 20°F
include returning too low of a water temperature
to the heat source (especially in the case of non-
condensing boilers, which can fail prematurely if
this is the case), and a more expensive installation if
tubing spacing must be reduced to satisfy the load
at the higher temperature drop. Ensure that the
final temperature drop selected does not result in a
return temperature to the heat source that is lower
than that permitted by the manufacturer. Return
temperature may be controlled with a thermostatic
bypass or reset control that monitors return water
temperature.