Daikin FTX25JVEA9, Руководство по обслуживанию

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Si18-201 System control
Main Functions 127
3.11.2 Outdoor Unit Motorized Valve High Pressure (Heating Capacity)
Control
Outline This function opens the gas pipe motorized valve then forms a discharge-suction bypass circuit
to prevent high pressure rise during cooling due to excessively low indoor heat exchange
capacity even when operating at the minimum frequency.
The peak-cut control, low Hz high pressure control and high pressure control lower the
operating frequency to the minimum level. If the high pressure is high, target high pressure
saturation temperature TDSET is calculated, and the gas pipe motorized valve and discharge
bypass motorized valve are controlled to attain the target high pressure saturation temperature.
Details When the operating frequency lowers to the minimum frequency due to the peak-cut control and
high pressure control, the heating capacity control is activated.
The heating capacity control provides 2-step control.
1st step: Opens the EVG to increase the condensing capacity of the auxiliary heat exchanger
located under the outdoor heat exchanger in order to decrease the high pressure.
2nd step: Opens the EVG fully. If the high pressure is high, the discharge bypass is used for the
capacity control.
The heating capacity control adjusts the EVG and EVP to vary the target high pressure
equivalent saturation temperature based on the peak-cut and high pressure control zones so
the target high pressure equivalent saturation temperature is attained.
The upper-limit and lower-limit values of target high pressure equivalent saturation temperature
shall be
between 48°C and 66°C respectively.
The target high pressure equivalent saturation temperature at start is 56°C.
Determination of motorized valve operating amount
The target high pressure equivalent saturation temperature is detected during each sampling
operation. The difference from the target high pressure equivalent saturation temperatures is
used to determine the amount of valve operation.
In case of high pressure equivalent saturation temperature > Target high pressure equivalent
saturation
temperature,EVG or EVP: To be opened
In case of high pressure equivalent saturation temperature < Target high pressure equivalent
saturation
temperature,EVG or EVP: To be closed
Decrease in target HP : 0.25˚C/40sec
Increase in target HP : 0.25˚C/40sec
Drooping zone
No-change zone
Reset zone
(M1017)