tekmar 268 Boiler Control - Manual (Page 10)

© 2010 D 268 - 11/10 10 of 32
CHARACTERIZED HEATING CURVE
The control varies the supply water temperature based on the outdoor air temperature. The control takes into account the type of
terminal unit that the system is using. Since different types of terminal units transfer heat to a space using different proportions of
radiation, natural convection and forced convection, the supply water temperature must be controlled differently. Once a terminal
unit is selected, the control varies the supply water temperature according to the type of terminal unit. This improves the control
of the air temperature in the building.
BOILER INDOOR DESIGN TEMPERATURE
The indoor design temperature is the room temperature that was used in the original heat loss calculations for the building. This
setting establishes the beginning of the characterized heating curve.
BOIL MAX BOIL DSGN
OUT DSGN
ROOM Occ
ROOM UnOcc
210
(99)
190
(88)
170
(77)
150
(66)
130
(54)
110
(43)
90
(32)
70
(2
50°F
(10°C)
-20
(-29)
0
(-18)
20
(-7)
40
(5)
60
(16)
80
(27)
Outdoor Air Temperature
Supply W
a
ter T
e
mperatur
e
Boiler Characterized
Heating Curve
Boiler Characterized
Heating Curve
BOIL MIN
BOIL IND
WWSD Occ
WWSD UnOcc
TERMINAL UNIT HIGH MASS RADIANT
(1)
LOW MASS RADIANT
(2)
FANCOIL
(3)
FIN-TUBE CONVECTOR
(4)
RADIATOR
(5)
BASEBOARD
(6)
BOIL DSGN
BOIL MAX
BOIL MIN
120°F (49°C)
140°F (60°C)
OFF
140°F (60°C)
160°F (71°C)
OFF
190°F (88°C)
210°F (99°C)
140°F (60°C)
180°F (82°C)
200°F (93°C)
140°F (60°C)
160°F (71°C)
180°F (82°C)
140°F (60°C)
150°F (66°C)
170°F (77°C)
140°F (60°C)
OUTDOOR DESIGN TEMPERATURE
The outdoor design temperature is the outdoor air temperature that is the
typical coldest temperature of the year where the building is located. This
temperature is used when doing the heat loss calculations for the building. If
a cold outdoor design temperature is selected, the boiler supply temperature
rises gradually as the outdoor temperature drops. If a warm outdoor design
temperature is selected, the boiler supply temperature rises rapidly as the
outdoor temperature drops.
BOILER DESIGN TEMPERATURE
The design supply temperature is the supply water temperature required
to heat the building when the outdoor air temperature is as cold as the
outdoor design temperature.
WARM WEATHER SHUT DOWN
When the outdoor air temperature rises above the WWSD setting, the
control turns on the WWSD pointer in the display. When the control is in
Warm Weather Shut Down, the boiler demand pointer is displayed if there
is a boiler demand. However, the control does not operate the heating
system to satisfy this demand. The control does respond to a DHW or
setpoint demand and operates as described in sections E & F.
ROOM
The room is the desired room temperature for the building and provides a parallel shift of the heating curve. The room temperature
desired by the occupants is often different from the design indoor temperature. If the room temperature is not correct, adjusting
the ROOM setting increase or decreases the amount of heat available to the building. A ROOM setting is available for both the
occupied (day) and unoccupied (night) periods.
TERMINAL UNITS
The control provides for a selection between six different terminal unit types: two types of radiant floor heat, fancoil, fin-tube convector,
radiator and baseboard. When a terminal unit is selected, the control automatically loads the design supply temperature, maximum
supply temperature, and minimum supply temperature. The factory defaults are listed below. These factory defaults can be changed
to better match the installed system. If a factory default has been changed, refer to section A to reload the factory defaults.