iWorx® SMZ1
505-048-2, Effective: March 10, 2015
17
© 2015 Taco Electronic Solutions, Inc.
• Termination: 0.197” (5.0 mm) Pluggable Terminal Blocks, 14-22
AWG
Environmental
• Temperature: 32
°F to 140
°F
(0
°C to 60
°C)
• Humidity: 0 to 90%, non-condensing
Agency Listings
• UL Listed for US and Canada, Energy Management Equipment PAZX and PAZX7.
Agency Compliances
• FCC Part 15 Class A
APPLICATION DESCRIPTION
The iWorx® SML1 is a self-contained interoperable controller for snow melting in a hydronic system. The SML1 main-
tains the temperature of up to four snow melt zones by operating valves and circulators in cooperation with a BLM
boiler controller or HPM heat pump controller. It may also be used as a stand-alone zone controller with a non-net-
worked heat source.
The temperature of each zone’s slab is controlled independently. Separate idle and melting temperature setpoints are
set for each zone.
The analog outputs for each zone are operated based on a proportional plus integral (P+I) control loop. The primary
output is turned on when any zone demand output is on. Group circulators are activated when a zone that they are
associated with has heat demand.
The SML1 may be set to communicate its heat demand to the BLM or HPM, which provides the appropriate supply
temperatures. The SML1 may be configured for a secondary loop supply, which uses the injection functions of the
BLM, or it may be set to use only the primary loop as a supply.
The commissioning switch displayed on the LCI can be set to turn on all outputs simultaneously for test purposes.
The zone valve outputs are capable of actuating 2-wire zone valves with up to 1.0 A current draw.
0-10V modulating outputs are provided for each zone to support modulating valves or circulators.
SEQUENCE OF OPERATION
This section describes the detailed sequence of operation for the SMZ1 control strategy. The italicized terms refer to
the settings available on the LCI. (See “Controller Identification” on page
Operational Modes
The SMZ1 has four distinct modes of operation.
Global Sense without Idle
When operating in Global Sense mode, the SMZ1 activates any zone when the Global Snowmelt Sensor input is active
and the zone's local slab temperature is below the slab melt setpoint temperature.
Global Sense with Idle
This mode operates similar to the Global Sense mode except it also activates when the zone slab temperature drops
below the idle temperature setpoint regardless of the state of the Global Snow Sensor.
Zone Sense without Idle
When operating in Zone Sense mode, the SMZ1 activates any zone when that zone's local Snowmelt Sensor input is
active and the zone's slab temperature is below the slab melt setpoint temperature.
