tekmar 654 Snow Melting Control Installation - Manual (Page 31)

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Programmable Schedules
To provide greater energy savings, the control can operate on
a programmable schedule. The schedule is stored in memory
and is not affected by loss of power to the control. If tekmarNet
®
communication is detected the control can become either a
schedule member or schedule master.
Zone Schedule ---------------------------------- ----------------------------------
The schedule only applies to the control. The control follows
its own schedule and the events are not communicated to the
tekmarNet
® system.
Master Schedule -------------------------------- --------------------------------
If the control is connected to other tekmarNet ® devices, then
the control can operate on a master schedule. A maximum of
four master schedules are available on the tekmarNet
® system.
Using master schedules simplify installation since one master
schedule may be used by multiple devices.
To create a master schedule:
Assign the control to be a schedule master by setting
Schedule in the Schedule menu to Master (MST) 1 to 4. •
To follow a master schedule:
Assign the control to follow a master schedule by setting
Schedule in the Schedule menu to Member (MBR) 1 to 4.
Schedule Types --------------------------------- ---------------------------------
The schedule type determines when the schedule repeats
itself. This control includes two different schedule types:
• 24 Hour: Repeats every 24 hours.
• 7 Day: Repeats on a weekly basis and allows for separate
event times for each day.
Events / Day
The events / day can be either 4 or 2. An event is a time at
which the control changes the target temperature. The event
time can be set to the nearest 10 minutes. To have the control
skip the event, enter “SKIP“ as the time. SKIP is found between
11:50 PM and 12:00 AM or 23:50 and 00:00 hours.
•
The control has a built-in time clock to allow the control to
operate on a schedule. A battery-less backup allows the
control to keep time for up to 4 hours without power. The time clock supports automatic adjustment for Daylight Saving Time
(DST) once the day, month and year are entered. Use the Time
menu to set the correct time, day, month and year.
Time Clock
Snow Melt Zones and Priority
Dividing a system into a number of snow melting zones and
prioritizing the zone operation reduces the size requirements
of the hydronic heating plant or the amperage of the electri-
cal service panel. This results in lower initial capital cost of
the snow melting system. The trade off is that some snow
melt zones may not be able to melt as soon as the snow fall
begins and the user must tolerate snow accumulation on the
slab. The snow melt system may have up to 12 snow melt
zones. Zone 1 has the highest priority and zone 12 has the
lowest. The priority setting in the tekmarNet
® menu allows
the installer to select the level of zone priority for entire snow
melt system. Changing the priority setting on one control
will update on all other snow melt controls at the same time.
The zone priority has 3 setting levels. There is some risk
that lower priority zones may ice up when they are shut off
by the higher priority zone. For example, if a high priority
zone should finish melting and allow a lower priority zone
to start melting, and then a new snow fall occurs, the high
priority zone will shut off the lower priority zones. This may
potentially allow the lower priority zones to ice over. The
limitations of zoning and using priority must be carefully
considered and discussed with the building owners and
occupants when designing the snow melting system.
Priority does not apply when the application mode is set to
Boiler. In this mode, the boiler is dedicated to a single snow
melting zone so priority is no longer applicable.