tekmar 654 Snow Melting Control Installation - Manual (Page 36)

© 2013 654_D - 06/13 36 of 44
Tandem Snow / Ice Detection
In systems where reliability of the snow melting system is
critical, it is possible to install two Snow / Ice Sensors 090
or 094 into a single snow melt zone. Both sensors are used
to detect snow or ice and if either sensor is wet the snow
melting zone starts melting. The zone continues to operate
until both sensors are dry. This allows snow or ice detection
over a wider area. In the event of a sensor failure, the snow
melting zone continues to function normally, giving building
maintenance staff time to troubleshoot and replace the sensor
if necessary.
In order to setup a zone using tandem snow / ice detection:
Step 1: Install two Snow Melting Controls 654 each having
their own Snow / Ice Sensor 090 or 094.
Step 2: Connect the two 654 together using tekmarNet ®
communication.
Step 3: In the tekmarNet ® menu, select the Snow Zone that
the 654 is to operate. There can be up to 12 different
Snow Zones. Both 654 controls must be set to the
same Snow Zone number.
Step 4: On one of the 654, select the Application Mode to
PWM, Boil, Mix or Elec. This control is the Snow
Zone Master and it will operate the snow melting
equipment.
Step 5: On the other 654, select the Application Mode to 090.
This control is the Snow Zone Member. This control
must be wired to power, tekmarNet
® communication,
and the Snow / Ice Sensor 090 or 094.
Pump Post Purge
Alert Relay
The control includes an auxiliary relay that can be configured to be either a system pump or an alert output. When the Auxiliary
Relay setting in the System menu is set to Alert, the relay closes whenever there is a local error code. A network error on the
tekmarNet
® communication system is not considered a local error code and the Alert Relay does not close if only a network
error is present. The Alert Relay is connected to the input power R and provides a 24 V (ac) powered signal when closed. An
isolation relay may be installed if a dry contact switch is required on the 3rd party equipment.
Exercising
In a hydronic snow melting system, the control operates the system pump as well as the mixing valve or mixing injection pump
every 3 days to prevent pump and valve seizure.
After a zone has finished heating, the boiler or heat source is shut off and the zone continues to operate for 20 seconds to post
purge heat from the boiler to the zone.
Snow Zone 1
Master
Operates
Snow Melting
Equipment
Snow Zone 1
Member
App
Mode
090
App Mode
PWM, Boil,
Mix, Elec
tekmarNet ® Communication
Snow Zone 1