Install Instructions

IM-PR 566442 1114 (Design Manual)
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5.9 Thermal mass considerations
Concrete, pavers or asphalt may be used in snow
melting systems.
Concrete
Refer to cement manufacturer for recommended
compressive strength, slump, aggregate size and
air content. Typical applications include:
• Compressive strength - 4,000 to 5,000 psi
• Slump - 3" max., 2" min.
• Typical 2" concrete above tubing
Asphalt
• Hot asphalt can damage tubing (refer to cross
sections for installation)
• Lower thermal conductivity than concrete
• Finest grade asphalt is best
• Stone diameter should not exceed 0.38"
• Typical 1½" sand bed above tubing
• Tubing should be secured to the insulation to
prevent contact with the hot asphalt
• During installation, ensure that tubing
temperature does not exceed 200°F
Pavers
• Space tubing 2" closer for each additional
inch of pavers > 2⅜" pavers
• Typical 1½" sand bed above tubing
5.10 Typical cross sections
Snow melt systems can be incorporated under
asphalt, concrete, pavers or other porous or non-
porous hardscapes. See Section 5.12.1 for typical
cross sections.
5.11 Controls
When selecting control packages for snow melt
systems, consideration must be given to piping
configurations, mixing options, heat exchangers
and control hardware.
5.11.1 Piping configurations
Piping for snow melting systems may be configured
as follows:
1. Completely separate heating source from
indoor heating piping
2. Thermally coupled to indoor heating piping
through a heat exchanger (e.g., when the
indoor system uses 100% water and the
snow melt uses a glycol solution)
5.11.2 Mixing options
Each of these piping configurations requires some
form of mixing or boiler modulation to ensure that
design delivery temperatures to the snow melt
area are achieved. Following are some of the
most common options used to achieve the design
supply temperature to a snow melt system:
• Mixing Valve – A mixing valve is controlled by
an electronic actuator that receives a signal
from a reset control. This control varies the
temperature being supplied to the manifold
by adjusting the amount of hot supply or cold
return water that is permitted to ow through
the valve. To optimize the performance
of the mixing valve (accurate mixing and
reduced head), select a mixing valve with
a Cv rating that is as close as possible to
the design ow through the valve. For snow
melting applications, required ow rates may
approach levels that trigger specication of
large-diameter mixing valves. The reason
for selecting a larger mixing valve in these
applications is to maintain acceptable
pressure drops through the valve. Select a
mixing valve size based on Table 5-15.
See
Section 5.6.2 for more information on calculating
the pressure drop associated with valves.
Viega’s 3-Way Valves
Size Connection Flow
¾" NPT 5
1" NPT 12
1¼" NPT 19
1½" NPT 29
2" NPT 47
Viega’s 4-Way Valves
Size Connection Flow
¾" NPT 7
¾" Copper 3
1" NPT 12
1" Copper 7
1¼" NPT 19
1¼" Copper 14
1½" NPT 29
2" NPT 47