6.10 Outdoor temperature-compensated control
6.10.1 Outdoor temperature-compensated supply air control
The function is basically available in systems with cooling coil and, additionally, in system
Anl 0. The function of
summer compensation
(–> section 6.7) can also be used for an out-
door temperature-compensated supply air control. The
Summer compensation when the out-
door temperature is greater parameter determines from which outdoor temperature onwards
the
Supply air temperature set point should be reduced. The Set point at an outside tempera-
ture of 32 °C parameter determines also the gradient of the characteristic curve.
Example:
A heating coil is to heat the supply air to 35 °C when the outdoor temperature is
−
15 °C .
The foot of perpendicular is to be at 15 °C outdoor temperature / 20 °C supply air temperature.
4
Supply air temperature set point = a = 35 °C
4
Summer compensation when the outdoor temperature is greater = b =
−
15 °C
4
Set point at an outdoor temperature of 32 °C = c
4
Supply air temperature minimum limit = d = 20 °C
4
Foot of perpendicular outdoor temperature = e = 15 °C
The calculation of the temperature required for the parameter
Set point at an outdoor tem-
perature of 32 °C results in:
c = a – (32 °C – b) · (a – d) / (e – b) = 11.5 °C
Parameters
WE
Range of values
Summer compensation when the outdoor temp. is greater
26 °C
–50 to 40 °C
Set point at an outdoor temperature of 32 °C
26 °C
0 to 40 °C
Supply air temperature set point
22 °C
0 to 50 °C
EB 5477 EN
59
Control functions
a
d
c
b
e
32
Fig. 22 · Outdoor temperature-compensated supply air control
Set point °C
Outdoor temperature °C