tekmar 274 Boiler Control - Manual (Page 25)

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Testing the Demands Terminals 21 – 25
1. Remove the front and bottom cover from the control.
2. Use an electrical test meter to measure (ac) voltage
between the Boiler Demand terminals (21-22) or the
DHW / Setpoint Demand terminals (23-24) or the Proof
Demand terminals (24-25).
When the demand device is on, a voltage between
20 and 260 V (ac) should be measured between the
appropriate demand terminals and the LCD should display
an indicator arrow pointing to Boiler Demand, DHW /
Setpoint Demand, or Proof Demand.
When the demand device is off, less than 5 V (ac) should
be measured between the terminals. •
•
Cleaning the Control
The control’s exterior can be cleaned using a damp cloth. Moisten the cloth with water and wring out prior to wiping control.
Do not use solvents or cleaning solutions.
DIP Switch Settings
Set the DIP switch settings prior to making adjustments
to the control through the user interface. Setting the DIP
switches determines which menu items are displayed in
the user interface.
Switch Settings
EMS / Demands
The EMS / Demands DIP switch selects whether a tekmar
outdoor sensor 070 or an external 0-10 or 2-10 V (dc) input
signal is to be connected to the Com - and Out + terminals
(2 & 3).
Set the EMS / Demands DIP switch to EMS if an Energy
Management System is providing an external analog input
signal to the control.
Set the EMS / Demands DIP switch to Demands if the
control is accepting a boiler demand and using the outdoor
sensor for outdoor reset.
Demands
Setback
Off
EMS
Rotate
Fixed Last
Pump Sequencer
Exercise
Off
Fixed Lead
First On / Last Off
First On / First Off
Lock / Unlock
Use this DIP switch to lock and unlock the Access Level
of the 274 and all connected tN4 devices, including tN4
thermostats. For details, see “Access Level”.
Once locked, the access level in all devices cannot be
viewed or changed. •
When the control is locked, a small segment representing
a padlock is shown in the bottom right hand corner of the
display (except in View and Time Menu)
Demands
Setback
Off
EMS
Rotate
Fixed Last
Pump Sequencer
Exercise
Off
Fixed Lead
First On / Last Off
First On / First Off
Off / Exercise
Use the Off / Exercise DIP switch to select whether or not
the control is to exercise all pumps, and hydronic zones
(zone valves and zone pumps) for 10 seconds every three
days of inactivity to prevent seizure.
Demands
Setback
Off
EMS
Rotate
Fixed Last
Pump Sequencer
Exercise
Off
Fixed Lead
First On / Last Off
First On / First Off
Setback / Off
Use the Setback / Off DIP switch to select whether or not
the control is to follow a schedule.
If the 274 is to be a schedule member or schedule master,
set the DIP switch to Setback to enable the Time and
Schedule menus and the Unocc items in the Adjust
menu.
If the 274 does not follow a schedule, set the DIP switch
to Off to disable the Time and Schedule menus and the
Unocc items in the Adjust menu.
Demands
Setback
Off
EMS
Rotate
Fixed Last
Pump Sequencer
Exercise
Off
Fixed Lead
First On / Last Off
First On / First Off
•
•
•
Control Settings