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

[5-3 HBC Control ]
5-3-7

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 figure shows the refrigerant flow for the heat recovery defrost. In the heat recovery defrost method, LEV1 and
LEV2 are fully opened and the heat is 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. In the bypass defrost method, LEV1 and LEV2 are closed
and the heat is not exchanged between the refrigerant and water.
The basic defrost method is the heat recovery defrost with the dip switch 001-9 on the HBC turned OFF (default). The bypass
defrost may be performed depending on the water temperature. Setting the dip switch 001-9 to ON performs the bypass de-
frost.
Main-HBC refrigerant system
TH14
Cooling-main
heat exchanger
TH12
TH16
TH15
S
M
Strainer
HIC
SV1
BS_05_M
21S4Mb
TH13
Water
Heating-main
heat exchanger
Water
TH11
LEV2
LEV3
PS PS3
Main-HBC water system
Valve block VB3a
21S4Ma
CPV1
PS1
PS
Water
Refrigerant
Cooling-main
heat exchanger
Refrigerant
Water
LEV1
Port No.1~No.3 Port No.4~No
TH31a TH31b TH31c TH31d
VB3b VB3c VB3d VB3e
M M M M
TH33
TH32
Refrigerant
Heating-main
Pw2
heat exchanger
PS
Pump1
TH35
Refrigerant
TH34
Pw4
PS
Pump2
chapter 5 -
TH
V
M
Pw1
PS
Pw3
PS
27