Direct Digital Controller
Direct Digital Controller fw 4.013 – Ed. 01/2013
111
•
Internal ambient temperature higher when the external temperature is higher:
the slope is
insufficient;
lower
the water temperature for external temperature 35°C (95° F) or
raise
the value for
external temperature 25°C (77° F).
•
Internal ambient temperature higher when the external temperature is lower:
the slope is too steep;
raise
the water temperature for external temperature 35°C (95° F) or
lower
the value for external
temperature 25°C (77° F).
If, however, the slope is correct (internal environment temperature stable on variation of the external
temperature), but the internal temperature does not coincide with that set as set-point, the following cases may
occur:
•
Internal ambient temperature still higher than the set point: in this case, intervention must be made on the
Offset parameter of the climatic curve, setting a
negative
value equal to the offset of the internal
temperature from the set-point; for example, if the set-point is 24 °C (75,2° F) and the effective internal
temperature is 27 °C (80,6° F), set the Offset parameter at a value of -3 °C (-5,4° F).
•
Internal ambient temperature still lower than the set point: in this case, a
positive
value must be set for the
Offset parameter of the climatic curve; for example, if the set-point is 24 °C (75,2° F) and the effective
internal temperature is 22 °C (71,6° F), set the Offset parameter at a value of 2 °C (3,6° F). Water T.
Figure 21
–
GRAPHICS OF THE “CONDITIONING CURVES”
Regarding heating, the family of climatic curves is indicated in Figure 22 and the choice of the curve to use is
made by specifying the value of a parameter that indicates the slope of the curve. The curve defined in this
way refers to an internal environment set-point temperature of 20 °C (68 °F) . If the set-point temperature is
different, the system automatically adapts the curve used.
To initially set a suitable heating climatic curve, operate as follows:
•
Obtain the data relative to the temperature necessary when the external temperature is equal to the
“project temperature” (for example: waterT = 60 °C (140 °F) when External = -10 °C (14 °F).
•
Using the Figure 22 graphics, select the curve that satisfies the requisite of the previous point; for the
example in the previous point, see Figure 23.
Take note of the value of the parameter that expresses the slope of the curve and set it.
For the example in the previous points, set the value of 1.5, as indicated in Figure 23.
NOTE
: if no curve passes through the point corresponding to the project temperature, select an
intermediate value between those of the curve immediately above or immediately below this point.
Water set point at Test.25° C = 10°C
Water set point at Test.77° F = 50° F
Water set point at Test.35° C = 7° C
Water set point at Test.95° F = 44,6° F
Curve for internal environment
T = 25 °C (77° F)
External environment T
(77° F)
(95° F)
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