tekmar 263 Boiler Control - Manual (Page 12)

© 2009 D 263 - 03/09 12 of 36
Section D1
Boiler
Reset
Section D: Boiler Reset Operation
Section D1: Boiler Reset Operation
BOILER DEMAND
A boiler demand is required in order for the control to provide heat to the heating system.
A boiler demand is generated by applying a voltage between 24 and 230 V (ac) across the
Boiler Demand
terminals (1 and 2). Once voltage is applied, the Boiler Demand pointer is
displayed in the LCD. If the control is not in Warm Weather Shut Down (WWSD), the control
closes the primary pump contact. The control calculates a boiler target supply temperature
based on the outdoor air temperature and the characterized heating curve settings. The
control then fires the boiler(s), if required, to maintain the target supply temperature.
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.
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 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.
INDOOR SENSOR
With the indoor sensor connected, the control is able to sense the actual room temperature. Indoor temperature feedback fine-
tunes the supply water temperature in the heating system to maintain room temperature. To adjust the room temperature, use the
Room Occ
or Room UnOcc setting in the ADJUST menu at the control.
The indoor sensor is connected to the Indr and Com terminals (20 and 21). In addition, power must be applied to the Boiler Demand
terminals (1 and 2) as described in the Boiler Demand section.
If a multiple zone system is used with an indoor sensor, proper placement of the indoor sensor is essential. The indoor sensor
should be located in an area which best represents the average air temperature of the zones.
1 2
Boiler
Demand
24 to 230 V (ac)
N
L
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