Measurement Modes in the Main Menu
45
6.7
Option „U value“
Fig. 50: Application example DC 430
Flow
with Special Wall Temperature Probe
Fig. 51: U value
The heat transfer coefficient (U value) describes
the heat flow W/m²k flowing through a building
element.
NOTE!
A Special Wall Temperature Probe is needed to
measure the heat transfer coefficient (see acces-
sories). All temperatures (also the inside air tem-
perature t
ai
and the outside air temperature t
ao
should be measured with the same sensor.
The temperature values measured by the Wöhler
DC 410
FLOW
and the Special Wall Temperature
Probe are necessary for the determination of the
U value. The u-value is calculated with the follow-
ing equation according to the DIN standard 4108.
AO
AI
WI
AI
i
current
t
t
t
t
U
U
current
U-value in W/(m²k), current value
t
AI
interior air temperature
t
WI
interior wall temperature
t
AO
outside air temperature
i
fix value, 7,69 W/(m²k)
All temperatures (also the interior air temperature
t
ai
and the outside air temperature t
AO
) should be
measured with the same temperature sensor.
