Application Guide

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© 2019 tekmar 671
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A - 08/19
On/Off Steam Valve A671-3 Mechanical
B1 = Boiler Enable
HX = Steam-to-Glycol Heat Exchanger
M1 = On/Off Steam Valve
P1 = System Pump
S1 = Snow/Ice Sensor 090 or 094
S2 = Snow Sensor 095
S3 = Slab Sensor 072 or 073
S4 = Outdoor Sensor 070
Legend
671
Snow/Ice Sensor Options
S4
P1
HX
V1
S1
S2
S3
Description
The WiFi Snow Melting Control 671 operates a steam valve and a steam-to-water heat exchanger to heat a glycol-filled snow
melting system.
• The system pump operates continuously when heating the slab during melting/idling/storm operation.
• The slab temperature is controlled by turning on and off the steam valve.
• The boiler relay is closed while the steam valve is open. This provides a signal to fire the steam boiler.
• The slab target is determined by the melting/idling/storm setpoint and by the measured outdoor air temperature.
The system operation is dependent on sensor selection, as listed in the table below.
Sensor options Operation methods
Sensor Sensor Model(s)
Auto Start/
Auto Stop
Auto Start/
Timed Stop
Manual Start/
Timed Stop
Slab Temperature
Control
S1 Automatic Snow/Ice Sensor 090 or 094 • – • •
S2 Aerial Snow Sensor 095 – • • –
S3 Slab Sensor 072 or 073 – – • •
S2+S3 Aerial Snow Sensor 095 and Slab Sensor 072/073 – • • •