tekmar 265 Boiler Control - Manual (Page 11)

11 of 36 © 2010 D 265 - 07/10
BOILER DESIGN TEMPERATURE
The boiler 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.
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.
ROOM
The ROOM setting 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 increases or decreases the amount of heat available to the building. A room setting is available for both
the occupied (day) and unoccupied (night) periods.
BOILER TARGET TEMPERATURE
The boiler target temperature is determined from the characterized heating curve settings and the outdoor air temperature. The
control displays the temperature that it is currently trying to maintain as the boiler supply temperature. If the control does not
presently have a requirement for heat, it does not show a boiler target temperature. Instead, “– – –” is displayed in the LCD.
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.
Terminal Unit High Mass
Radiant (1)
Low Mass
Radiant (2)
Fancoil
(3)
Fin-Tube
Convector (4)
Radiator
(5)
Baseboard
(6)
BOIL DSGN 120°F (49°C) 140°F (60°C) 190°F (88°C) 180°F (82°C) 160°F (71°C) 150°F (66°C)
BOIL MAX 140°F (60°C) 160°F (71°C) 210°F (99°C) 200°F (93°C) 180°F (82°C) 170°F (77°C)
BOIL MIN OFF OFF 140°F (60°C) 140°F (60°C) 140°F (60°C) 140°F (60°C)
High Mass Radiant (1)
This type of a hydronic radiant floor is embedded in either a thick concrete or gypsum
pour. This heating system has a large thermal mass and is slow acting.
Low Mass Radiant (2)
This type of radiant heating system is either attached to the bottom of a wood sub-floor,
suspended in the joist space, or sandwiched between the sub-floor and the surface.
This type of radiant system has a relatively low thermal mass and responds faster than
a high mass system.
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.
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.
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
(21)
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 INDR
WWSD OCC
WWSD UNOCC