Honeywell EXCEL 5000 User Manual page 118

ALPHABETIC REFERENCE
74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)
The controller uses parameters to performs several tasks to ensure economic
heating. Apart from the basic functions it performs (to control the desired
temperature according to a time program), the controller also ensures that certain
temperatures are maintained to protect the system or building. Default settings for
each parameter are based on years of experience to ensure this safe operation.
Adjustments are only necessary in very special cases.
Heating Curve
The weather-compensated controller requires a heating curve for each heating
circuit to determine the correct flow temperature setpoint according to outside air
temperature. The heating curve graph indicates the relationship between outside air
temperature and associated flow temperature.
For radiator heating systems, a heating curve slope 1.6 and curvature 1.33 is the
default setting. The higher the curvature value, the more pronounced the curvature.
Recommended curvature values are:
• Floor heating systems 1.1 (with a slope of 0.8 and maximum limit of flow
temperature set to highest value, for example, 50)
• Standard radiatorsor panel-type radiators 1.3
• Convectors 1.4 through 1.6
It is important to set the curvature value appropriately for floor heating systems or
damage may result when outside air temperature is low and flow temperatures go
too high. A safety thermostat is recommended to switch off the circulating pump if
flow temperatures are too high.
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EXCEL CARE CONTROL ICONS