SC-Z20
DESIGN AND INSTALLATION NOTES
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Extra consideration should be given when applying any zone control system to a building that
requires large amounts of cooling in the core zones during cold weather. Consider adding
auxiliary heat to external zones or using one system for the core zones and one system for the
external zones.
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It is recommended that the system installation be limited to 50 tons of capacity. Rooftop units
with economizers and relief dampers are strongly recommended for buildings with core
cooling loads.
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Over-sizing of the HVAC equipment is not recommended. In most cases, it is better to slightly
undersize the equipment.
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It is recommended that the HVAC equipment have two stages of heating and two stages of
cooling.
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The pressure drop through the zone dampers is negligible and should not be a factor when
sizing branch duct runs.
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Zone dampers are rated up to 2” w.c. of static pressure and up to 2,000 fpm.
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Zone dampers should be installed as far back from discharge air grille as possible. Flex duct
should be used for the last 5 feet of each branch run.
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Bypass dampers should be sized for 90% of the total system air flow at 2,500 fpm.
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The SC-Z20 panel should be located near the center of the building to keep
wire runs as short as possible.
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DO NOT mount the SC-Z20 panel on or inside the rooftop unit.
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Use a separate 24 VAC, rated at the proper VA transformer for the SC-Z20 panel.
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All wiring should be 18 gauge standard or plenum rated thermostat wire.
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Wiring should comply with all local and national codes.