8.2
Reference design temperature
The reference design temperature is the boiler supply temperature required by
the structure and the heating system to achieve the target room temperature at
an outdoor temperature of 14°F (-10°C).
The reference design temperature helps define the characteristic heating curve
which is the basis for outdoor reset.
It follows the idea that the colder the weather, the greater the heat loss of a
structure, and the higher a boiler supply temperature needed to compensate for
the resulting losses.
The factory default setting results in a characteristic heating curve as shown
(Fig. 8,
Item 1
).
The reference design temperature (Fig. 8,
Item 2
) is used to adjust the heating
curve. Depending on the measured outdoor temperature, the boiler supply
temperature is changed in order to keep the room temperature stable and save
as much on fuel as possible (Fig. 8).
When changing the reference design temperature, the gradient of the heating
curve is adjusted.
Example (Fig. 9):
Design temperature 140°F (60 °C) for +5°F (-15 °C) outdoor temperature.
A boiler temperature of 140°F (60°C) is achieved by setting the reference design
temperature to 133°F (56°C) (at an outdoor temperature of 14°F (-10°C)),
The reference design temperature can be set from 86 to 194°F (30 to +90°C).
Further information on this can be found on the next page.
The factory setting is:
167
REF TEMP
°F
Fig. 8
Determining the heating
curve
194 (90)
167 (75)
158 (70)
68
60
50 41
32
23 14
+5
(+20) (+15) (+10) (+5) (±0) (-5) (-10) (-15)
68 (20)
86 (30)
104 (40)
122 (50)
140 (60)
176 (80)
1
Outdoor temperature [°F(°C)]
Boiler supply te
mperature [°F
(°C
)]
2
Fig. 9
Determining the heating
curve
194 (90)
167 (75)
158 (70)
68
60
50 41
32
23 14
+5
(+20) (+15) (+10) (+5) (±0) (-5) (-10) (-15)
68 (20)
86 (30)
104 (40)
122 (50)
140 (60)
176 (80)
Outdoor temperature [°F(°C)]
Boiler supply temperatu
re [°F(°
C)]
With PERIM HTG:
167°F (75°C)
With FLOOR HTG:
113°F (45°C)
Logamatic 2107 controls - We reserve the right to make any changes due to technical modifications.
3
2
5
4
Heating circuit data
8
