Maximum economy changeover (MECH), (cont’d)
When controlled via the heating sequence: Possibility 2: Changeover
at an adjustable value
For that purpose, MECH
input 1 (MECH 1) must
be assigned an alalog
input. Function with
TYPE = ERC:
When the set MECHU limit value (MECHSET) is exceeded, the output of the HR
equipment (HREC) will be inverted.
When controlled via the cooling sequence:
When the set MECH limit value (MECHSET) is exceeded, the output of the HR
equipment (HREC) will no longer be inverted.
X3
OUTS
0 %
CTLOOP 1
y1 y2
HREC
HREC
OT > MECH limit value
OT < MECH limit value
Examples of changeover at an adjustable value:
Application examples
• Changeover at an outside temperature >25 °C
• Changeover at an outside enthalpy > 30 kJ/kg
• Changeover via an external enthalpy difference processor at an
enthalpy difference ≥2 kJ/kg
66 / 174
Siemens Universal Controllers RLU2… CE1P3101en
Building Technologies Aggregates 29.08.2008
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