tekmar 275 Boiler Control - Manual (Page 20)

© 2012 275_D - 11/12 20 of 48
Boost Section P
When the control changes from the UnOccupied mode
to the Occupied mode, it enters into a boosting mode. In
this mode, the supply water temperature to the system
is raised above its normal values for a period of time to
provide a faster recovery from the setback temperature of
the building. The maximum length of the boost is selected
using the BOOST setting in the Adjust menu.
Typical settings for the boost function vary between 30
minutes and two hours for buildings that have a fast
responding heating system. For buildings that have a
slow responding heating system, a setting between four
hours and eight hours is typical. After a boost time is
selected, the setback timer must be adjusted to come out
of setback some time in advance of the desired occupied
time. This time in advance is normally the same as the
BOOST setting.
If the building is not up to temperature at the correct time,
the BOOST setting should be lengthened and the setback
timer should be adjusted accordingly. If the building is
up to temperature before the required time, the BOOST
setting should be shortened and the setback timer should
be adjusted accordingly. If the system is operating near
its design conditions or if the supply water temperature
is being limited by settings made in the control, the time
required to bring the building up to temperature may be
longer than expected.
tekmarNet ® 4 Communication Section R
tekmarNet ® 4 (tN4) communicates between tN4 devices
(thermostats, Reset Module and Expansion Modules). Each
tN4 device is connected to a tN4 communication bus using
two wires. Each tN4 bus adjusts a single water temperature
in the system using indoor temperature feedback. The
Boiler Control 275 allows for one tN4 bus. This allows you
to control a system with one water temperature. A system
that has more than one tN4 bus is referred to as a tN4
network.
Bus 1
Network
tekmarNet ® 4
Thermostats
275
Boiler Control 275
The Boiler Control 275 is the system control for a hydronic
heating system. The 275 operates up to 4 modulating boilers,
a domestic hot water tank, and responds to other heating
requirements such as pool heating and snow melting. The
275 also coordinates and optimizes the operation of all the
tN4 thermostats.
tN4 Thermostat
The tN4 thermostat operates heating, cooling, and or
ventilation equipment for a zone. Several tN4 thermostats
may work in a group when operating a cooling system. Up
to 24 tN4 devices can connect to a single tN4 bus.
The control will exercise the Combustion Air Damper, all
pumps, and tN4 zones (zone valves and zone pumps) for
10 seconds every three days of inactivity to prevent seizure.
To enable exercising, switch the Exercise / Off DIP to the
Exercise position. 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.
Note: The Setback / Off DIP Switch must be set to Setback
before the Time menu can be accessed.
Time Clock Section O
Daylight Savings Time Modes
Mode DST Start DST End
1 1st Sunday in April Last Sunday in October
2 2nd Sunday in March 1st Sunday in November
The control will exercise the Combustion Air Damper, all
pumps, and tN4 zones (zone valves and zone pumps) for
10 seconds every three days of inactivity to prevent seizure. To enable exercising, switch the Exercise / Off DIP to the
Exercise position.
Exercising Section Q