Proportional range: Setting knob
A
To make sure that the control unit maintains the desired room tem-
perature, an operating range (regulation range) is to be given. The
operating range defines the relation between the room temperature
and flow temperature or the setting of the regulating unit. Since
there is always a specific relation (proportion) between the room
and flow temperature in the operating range, it is also called
proportional range Xp. For most 90/70 hot water heating systems,
A
è
4
is correct as the basic setting.
If with this setting (
A
è
4
) a constant room temperature is obtai -
ned and the mixing valve position remains more or less the same
over a long period of time, no correction is necessary.
If, however, periodic room temperature oscillations occur, becau-
se the mixing valve opens and closes intermittently, a larger pro-
portional range is to be set (e. g.
A
è
5
).
Description of the Operating Diagram
With the setting knob
A
the proportional range can be set. The
numeric value set on setting knob
A
means a proportional range in
% (or °C) for an operating range of the actuator of 0 to 100 %. The
smaller the numeric value on the setting knob
A
, the steeper the
operating characteristic curve of the regulation is. A steep opera-
ting characteristic curve implies that already at a small room tem-
perature oscillation a relatively intense heat convection to the
room occurs.