Install Instructions

IM-PR 566442 1114 (Design Manual)
124
5.11.3 Selecting a heat exchanger
For systems that employ a heat exchanger, Viega’s
heat exchangers are very cost effective in snow
melt systems and provide high outputs, fast
response and separation of the fluids.
Use the following procedure to select a heat
exchanger for a snow melt system. Procedure:
1. Determine the total Btu/hr required for the
snow melt system.
2. Select the appropriate heat exchanger model from
the table, based on the total Btu/hr required.
3. Check the total gpm required. If the gpm
requirement of the snow melt system is
greater than the gpm listed in the selection
table, select a larger model to match the gpm
and pressure drop needs, or install a bypass
balancing valve. This will allow full flow and
optimum pressure drop for the pump. This
applies to the gpm on both boiler and glycol sides.
For snow melt system, 100°F in - 130°F out (40% P.G.)
Connected to boiler, 180°F supply - 150°F return
Viega Model BTUH
Side A Boiler Side B Snow Melt Circuit
GPM PD (psi) GPM PD (psi)
22006 (¾" MPT) 125,000 8.6 2.9 9.0 3.1
22007 (1" MPT) 250,000 17.2 2.2 18.0 2.7
22008 (1¼" MPT) 500,000 34.4 2.8 36.1 3.6
Table 5-18
5.11.4 Control hardware
Viega provides a Basic Snow Melt Control and an
Advanced Snow Melt Control. Select one of these
controls based on the guidance in this section.
Basic Digital Snow Melt Control II
The Basic Digital Snow Melt Control II is typically
used in small-to medium-size residential areas,
driveways, walkways, patios and steps. The Basic
Digital Snow Melt Control II is recommended under
the following conditions:
• Economical system required
• Snow sensor cannot be mounted in thermal mass
NOTE:
Snow sensor should be located outside of slab in
landscape area.
Figure 5-10
Features include:
• Automatic snow melt activation
• Slab high-limit
• Senses air temperature
• Senses falling snow
• Timer switch for manual override activation
Advanced Snow Melt Control
The Advanced Snow Melt Control is typically used
in medium- to large-size residential, commercial
and industrial areas, building entrances, parking
ramps and lots, and emergency entrances. Use this
control when accurate ice and snow detection is
required. Features include:
• Slab protection (The control limits the rate at
which heat can be applied to the slab through
the ∆T Max setting.)
• Boiler protection
• Idling capability
• Cold weather cut-out
• Variable speed injection pump or floating action
Figure 5-11