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Building Technologies Modular Heating Controller RMH760B CE1P3133en
HVAC Products 5 General functions, fundamentals 05.02.2007
If some other heat consumer without absolute priority is in the same heat distribution
zone, its value will be ignored, even if it is greater.
Generally, the function of absolute DHW priority in combination with heating circuits
does not pose any problems; nevertheless, the correct plant function must always be
kept in mind.
The use of absolute DHW priority poses problems especially in connection with ventila-
tion plants since they often call for low flow temperatures.
In the case of shifting priority or with no priority, DHW heating makes it possible to
select whether the heat demand signal shall be evaluated the normal way (maximum
selection), or whether the DHW flow temperature setpoint shall be adopted as the
resulting setpoint.
Refer to section
10.10 “DHW priority”.
5.7 Mixing valve control
5.7.1 Control
Main menu > Commissioning > Settings > … or
Main menu > Settings > Heating circuit 1 (or 2 or 3) > Mixing circuit controller
Main menu > Settings > DHW > Controller primary circuit
Main menu > Settings > DHW > Controller maint sec temp
Main menu > Settings > DHW > Controller consumers
Main menu > Settings > Primary controller > Mixing circuit controller
Main menu > Settings > Main controller > Mixing circuit controller
Main menu > Settings > Boiler > Return control
Operating line Range Factory setting
Actuator run time 1…600 s
P-band Xp 1…100 K
Integral action time Tn 0…600 s
Depending on
various settings
5.7.2 Setting aids
With the help of the P-band (Xp) and the integral action time (Tn), the mixing valve
algorithm can be optimally adapted to the relevant controlled system.
The controller is supplied with the control parameters set to values suited for the major-
ity of controlled systems (typically flow temperature control with a 3-port mixing valve).
In the case of difficult controlled systems (e.g. heating circuit with heat exchanger), the
control parameters must always be matched to the type of controlled system.
3133D88
T
T
3133D89
A controlled system is usually characterized by the step response. This is explained on
the basis of the following example of a mixing heating circuit.
At the point in time t
o
, the actuating device (actuator of mixing valve) shall be opened
from 40 % to 80 %. As a result, the flow temperature will rise by Δx.
Setting choices
Setting with the help
of the step response
Example
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