4-Way Valve Operation - Daikin FTX25JVEA9 Service Manual

System control
3.37

4-Way Valve Operation

3.37.1 4-Way Valve Operation Security
Purpose of the This function ensures proper operation of the 4-way valve. (Because the pilot-system drive
method is used, the current from the coil cannot provide fail-proof 4-way valve operation.
Function
Therefore, the difference of pressure before and after the valve is used to ensure proper valve
operation.)
Outline Because the pilot-system drive method is used, the current from the coil cannot provide fail-
proof 4-way valve operation. Therefore, the use of the difference of pressure before and after
the valve is required. At the time of operation when the 4-way valve switches, the operating
frequency exceeding a specified frequency is output for a predetermined time duration to
ensure differential pressure necessary for the 4-way valve operation.
Details
Continuing time of 4-way valve
operation
Frequency of 4-way valve operation
3.37.2 4-Way Valve Switching
Outline When the outdoor heat exchanger is used as a condenser (in cooling and defrosting), the 4-way
valve is not supplied with current. When the indoor heat exchanger is used as a condenser, it is
supplied with current. To reduce the switching noise when heating operation stops (ON →
OFF), the 4-way valve switching after heating operation shutdown is delayed.
Details The 4-way valve switching delay is 140 seconds for OFF delay.
To reduce power consumption during current flow, a OFF process is conducted when the
heating thermostat OFF time exceeds 60 minutes.
166
Cooling Heating
90sec 90sec
62Hz 41Hz
Si18-201
Main Functions