Defrost Operation Control - Mitsubishi Electric PUHY-M200YNW-A1 Service Handbook

[5-3 Hydro Unit Control ]
5-3-4

Defrost Operation Control

(1) Defrost cycle type
The defrost cycle has following two types: Bypass defrost that is the same method as that used in a CITY MULTI series sys-
tem and heat recovery defrost (default) that the heat is collected from the water circuit and the defrost cycle ends early.
The following figures shows the refrigerant flow for the bypass defrost and the heat recovery defrost. In the bypass defrost
method, LEV1 is closed and the heat is not exchanged between the refrigerant and water. In the heat recovery defrost method,
the defrost cycle ends early because the heat is caught from the water.
The basic defrost method is the heat recovery defrost with the dip switch 001-10 on the Hydro unit turned OFF (default). The
bypass defrost may be performed depending on the water temperature. Setting the dip switch 001-10 to ON performs the by-
pass defrost.
The bypass defrost
Hydro unit refrigerant system
S
Strainer
Check valve
CV1
Solenoid valve
SV1
S
Strainer LEV1
The heat recovery defrost
Hydro unit refrigerant system
S
Strainer
Check valve
CV1
Close
Solenoid valve
SV1
S
Strainer LEV1
24
- chapter 5
TH13
Water
PS
Prf
Heat
exchanger
TH11
Water
Close
Refrigrant flow
TH13
Water
PS
Prf
Heat
exchanger
TH11
Water
Refrigrant flow
Hydro unit water system
TH32
Refrigerant
Heat
exchanger
PWD
PS
TH35
Refrigerant
Water pump
WP1
Manual rereif valve
MRV
Water flow
Hydro unit water system
TH32
Refrigerant
Heat
exchanger
PWD
PS
TH35
Refrigerant
Water pump
WP1
Manual rereif valve
MRV
Water flow
Water pressure
protection valve
PRV
PWS
PS
Strainer
(accessory)
S
Expansion vessel
Main piping
Water pressure
protection valve
PRV
PWS
PS
Strainer
(accessory)
S
Expansion vessel
Main piping
BS_05_E