Daikin J Series Service Manual download pdf (Page 122)

SiE18-201 System control

Main Functions 111

3.30 SH Control in Cooling Operation

Purpose of the

Function

This function ensures appropriate refrigerant distribution when many room units are operating in

the cooling mode.

Outline The heat exchanger temperatures and gas pipe temperatures of operating room units are

detected by the gas pipe thermistors, and the motorized valves' flow rates are corrected so as to

adjust each room unit's heat exchanger temperature and gas pipe temperature (hereafter

referred to as SH) close to the target values.

When SH is higher than average → Opens the valve of that room unit

When SH is lower than average → Closes the valve of that room unit

However, the closing operation is restricted to prevent the valve operation that results in a flow

rate that exceeds a certain level at one time. When the liquid pipe temperature is higher than the

heat exchanger temperature, the motorized valve is opened without providing the above control.

(Protection function to prevent rotor dew condensation)

Details The gas pipe temperature and indoor heat exchanger temperature are detected at the time of

every sampling time of 40 sec for the cooling SH control.

In order to prevent dew condensation in connection pipe, gas pipe lower-limit temperature is set

as follows.

Gas pipe lower-limit temperature = 0.2 ° DOA + 1

Outside Temperature Gas Pipe Lower-Limit Temperature

-5 0

10 3

15 4

20 5

25 6

30 7

35 8

40 9

45 10

-20 0 20 40 60

Outside temperature

Gas pipe lower-limit temperature

(M1049)

1 2 ... 117 118 119 120 121 122 123 124 125 126 127 ... 343 344

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Daikin J Series Service Manual Page 122