User Manual

Siemens Building Technologies VISONIK DCS Functions and System Messages VVS18 CM2U8567E / 04.1999
Landis & Staefa Division System Messages --- DCS Messages 3-77
OSTP: exp. period to OCC xx>=yyh
DIAG TYP 00:00:00 NAME
OSTP: exp. period to OCC xx>=yyh
->MSGDEV (M.OTHT)
The pre-heating or pre-cooling time calculated by OSTP for the NAME zone, displayed
in xx hours, exceeds yy hours.
Such an excessive action time is interpreted by OSTP as "impossible", i.e., it must have
occurred as a result of either a defect in the plant or in the measured values (see
possible reasons below). The heating and cooling zone constants are constantly being
optimised. Nevertheless, they can be reset to programmed initial values when plant
defects are assumed to have corrupted them. Such corruptions could, of course,
negatively influence adaptation to the inertial characteristics of the building, resulting in
improper pre-heating or pre-cooling.
Reasons for this message could be
–
Incorrect measurement values (defective sensors, etc.)
–
Windows inadvertently left open in the building.
–
Frost protection limit set too low.
The heating or cooling plant is not able to reach the setpoint within zz hours.
–
A poor heating/cooling sequence on the previous day, which improperly adjusted the
building zone constants.
Check measured values. Possibly increase the frost protection limit (SPHD parameter).
The building zone constants are automatically set back to their initial values following
the message.
Explanation
Action