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Operation
User reference guide
40
EWAA004~008D2 + EWYA004~008D2
Packaged air-cooled water chillers
and packaged air to water heat pumps
4P688016-1 – 2022.04
5.8 Weather-dependent curve
5.8.1 What is a weather-dependent curve?
Weather-dependent operation
The unit operates 'weather-dependent' if the desired leaving water temperature is
determined automatically by the outdoor temperature. It therefore is connected to
a temperature sensor on the North wall of the building. If the outdoor temperature
drops or rises, the unit compensates instantly. Thus, the unit does not have to wait
for feedback by the thermostat to increase or decrease the leaving water
temperature. Because it reacts more quickly, it prevents high rises and drops of the
indoor temperature.
Advantage
Weather-dependent operation reduces energy consumption.
Weather-dependent curve
To be able to compensate for differences in temperature, the unit relies on its
weather-dependent curve. This curve defines how much the leaving water
temperature must be at different outdoor temperatures. Because the slope of the
curve depends on local circumstances such as climate and the insulation of the
house, the curve can be adjusted by an installer or user.
Types of weather-dependent curve
There are 2 types of weather-dependent curves:
▪
2-points curve
▪
Slope-offset curve
Which type of curve you use to make adjustments, depends on your personal
preference. See
"5.8.4 Using weather-dependent curves"
Availability
The weather-dependent curve is available for:
▪
Main zone - Heating
▪
Main zone - Cooling
▪
Additional zone - Heating
▪
Additional zone - Cooling
INFORMATION
To operate weather-dependent, correctly configure the setpoint of the main zone
and additional zone. See
"5.8.4 Using weather-dependent curves"
43].
5.8.2 2-points curve
Define the weather-dependent curve with these two setpoints:
▪
Setpoint (X1, Y2)
▪
Setpoint (X2, Y1)