Heating Curve =
For example:
• design outdoor temperature = 5
°
F (-15
°
C)
• room temperature = 70
°
F (21
°
C)
• design supply temperature = 160
°
F (71
°
C)
Heating Curve =
=
= 1.4
8
Heating Curve
As outdoor temperatures drop, heat losses from a space become
greater and the heating system supply water temperature must be
raised to maintain a constant room temperature. The heating curve
value describes how many degrees the supply water temperature is
raised for a one degree drop in outdoor temperature. The supply
temperature starts to increase when the outdoor temperature falls
below the WWSD point. To calculate the correct setting for the Heating
Curve, use the following formula.
design supply temperature – room temperature
room temperature – design outdoor temperature
0.4
2.0
3.6
Heating Curve
Outdoor air temperature
Supply water temperature
50
(10)
30
(-1)
10
(-12)
-10
°
F
(-23)
°
C
110
(43)
70
(21)
70
(21)
90
(32)
210
(99)
170
(77)
150
(65)
130
(54)
190
(88)
3.6 3.0 2.4 2.0
1.6
0.8
0.4
1.0
0.6
90
(32)
50
°
F
(10)
°
C
Heating
Curve
WWSD
Point
1.2
160
°
F - 70
°
F
70
°
F - 5
°
F
90
°
F
65
°
F
For more information regarding the Heating Curve, refer to page 2 of this brochure. If the actual designed supply water temperature
for a system is unknown, a trial setting can be calculated using these typical supply temperatures:
• Fan coils …180
°
to 210
°
F (82
°
to 99
°
C) • Baseboards …160
°
to 190
°
F (71
°
to 88
°
C) • Radiant floors …100
°
to 130
°
F (38
°
to 54
°
C).
Occupied temperature
When there is no room temperature feedback to the control, the Occupied dial setting determines the starting
point of the heating curve (WWSD point) and the Heating Curve setting will reset the water temperature as
described in the Heating Curve instructions above.
When an Indoor Sensor 074 is connected to the control, the Occupied dial setting becomes the actual controlled
temperature of the room. This feature will help the control compensate for an incorrectly set heating curve
or for unexpected internal heat gains or losses. If the room temperature is too high or too low, the indoor
sensor allows the heating curve to be shifted up or down accordingly.
When a tekmar Zone Control or 2K RTU (Room Temperature Unit) is connected to the control, the RTU
setting
becomes the controlled temperature and the Occupied dial becomes inactive.
Unoccupied temperature
The Unoccupied dial operates in the same way as the Occupied dial.
When the terminals
Com Sen — UnO Sw (17 and 18) are shorted out, the control switches from operating
at the Occupied dial setting to operating at the Unoccupied dial setting. When a tekmar Zone Control or 2K
RTU (Room Temperature Unit) is connected to the control, the RTU setting becomes the controlled temperature
and the Unoccupied dial becomes inactive.
Zone Control/Indoor Sensor switch
When this selector switch is in the "Indoor Sensor" position, and a tekmar Indoor Sensor 074 or a tekmar 2K
RTU is connected, the control receives room temperature feedback from the RTU or Indoor Sensor and the
Occupied/Unoccupied dials operate as described above.
When the switch is in the "Zone Control" position, and a tekmar Zone Control is connected, the control receives
information from the Zone Control that allows the heating curve to be shifted so the supply water temperature
is hot enough to satisfy the requirements of the zone with the highest heat demand.
DHW
When the control receives a DHW Demand signal from either a DHW Sensor or from 24V applied to the
DHW Dem terminals, the control will operate in the DHW mode.
See DHW operation, pg. 4
DHW during Unoccupied mode
When this selector switch is in the "On" position, DHW will continue to be generated when the control is
switched into the Unoccupied mode and a DHW Demand signal is received. When the switch is in the "Off"
position, the DHW mode becomes inactive when the control is in Unoccupied mode and the control will ignore
any DHW Demand signal.
DHW Priority switch
When this selector switch is in the "On" position, DHW generation will be given priority over heating operation
when a DHW Demand signal is received. When the switch is in the "Off" position, DHW generation is
simultaneous with heating operation.
See Application Brochure A 252.
DHW Valve/Pump switch
Set this selector switch to the "Valve" position when a valve is used in DHW generation and the "Pump"
position when using a pump.
See Application Brochure A 252.
Occupied
35
(2)
105
(41)
70
°
F
(21
°
C)
140
°
F
80
200
DHW
35
(2)
105
(41)
70
°
F
(21
°
C)
Unoccupied
1
2
3
4
5
6
7
8
Auto
Stage
1 2
Perm. Heat Demand
External Heat Demand
Indoor sensor
Zone control
DHW during unoccupied
DHW priority
Rotate
Off
DHW valve
DHW pump
1
2
3
4
5
6
7
8
Auto
Stage
1 2
Perm. Heat Demand
External Heat Demand
Indoor sensor
Zone control
DHW during unoccupied
DHW priority
Rotate
Off
DHW valve
DHW pump
1
2
3
4
5
6
7
8
Auto
Stage
1 2
Perm. Heat Demand
External Heat Demand
Indoor sensor
Zone control
DHW during unoccupied
DHW priority
Rotate
Off
DHW valve
DHW pump
