4. Special Controls

W-2WAY ECO-i SYSTEM Control Functions

4-3-6. Outdoor unit cycle defrost

Outdoor unit cycle defrost is performed in systems where 2 outdoor units are connected to the refrigerant system.

(1)Description of outdoor unit cycle defrost

With this defrost method, when 1 outdoor unit operates in defrost mode (heat exchanger operating as a con- denser), another outdoor unit operates as an evaporator in the same way as in ordinary heating mode.

In this way, the other outdoor unit is heating the unit where defrost is occurring. When 1 outdoor unit completes

defrost, the other outdoor unit performs defrost in the same way.

1 Because the amount of time that the unit operates as an evaporator is very short, there is little danger of frost forming again quickly. Rather, because the heat source is very powerful, it is possible to shorten the defrost operating time.

(2)Defrost sequence

Outdoor unit cycle defrost is always completed in 2 defrost operations.

(A) When there are 2 outdoor units

Defrost

outdoor unit

Evaporator outdoor unit

Switch

Evaporator outdoor unit

Defrost

outdoor unit

First operation

Second operation

• Defrost flow

E: Evaporator operation

 

 

 

 

 

 

 

 

 

 

 

 

C: Condenser operation

 

 

 

 

 

 

 

 

 

 

 

 

S: Shut off

 

 

 

 

 

 

 

 

 

 

 

 

E C: Switching from evaporator operation to condenser operation

 

 

C E: Switching from condenser operation to evaporator operation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Defrost

Defrost in

Switch

 

Defrost in

Defrost

 

 

 

 

 

preparation

progress

 

progress

preparation

 

 

 

 

 

 

 

 

Outdoor unit(s) where defrost occurs first

 

E C

C

 

 

C

E

E

 

 

 

E or S

Outdoor compressor(s) where defrost occurs first

 

OFF

ON

 

 

OFF

ON

 

 

OFF

Outdoor unit(s) where defrost follows later

 

E

E

Defrost

E

C

C

 

Defrost

C E or S

Outdoor compressor(s) where defrost follows later

 

ON

ON

OFF

ON

OFF

 

 

 

 

 

 

 

end

 

 

 

 

 

end

 

 

Stopped indoor unit(s)

 

S

S

 

 

S

S

 

 

S

 

judgment

 

 

judgment

Indoor units where fan is operating

 

S

S

 

S

S

 

S

 

 

 

 

 

 

 

Heating mode indoor

 

Thermostat ON

 

C

C

 

 

 

C

C

 

 

 

C

units

 

 

Thermostat OFF

 

C

C

 

 

 

C

C

 

 

 

C

 

Time

 

 

1 min

Max. 6 min

1 min

 

Max. 6 min

1 min

1 - 12

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Sanyo CHDXR09663, CHDXR07263, CHDX09663, CHDX07263 service manual Outdoor unit cycle defrost, Off
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