Bypass Control; Plate Heat Exchanger Control - Mitsubishi Electric PURY-M200YNW-A1 Service Handbook

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

Bypass Control

Solenoid valves have two types: (SV1) that bypass the high- and low- pressure sides; LEV (LEV3). They perform the following
functions.
(1) Bypass solenoid valve (SV1) (ON: open)
Operation mode
Cooling-only Thermo-ON
Cooling-main Thermo-ON
Heating-only Thermo-ON
Heating-main Thermo-ON
Defrost
Stop
Cooling-only Thermo-OFF
Thermo-OFF (Heating-only, Mixture of
units in cooling and heating)
Cooling-only test run
Test run for stop
5-3-6

Plate Heat Exchanger Control

(1) Cooling-only Thermo-ON and Cooling-only test run
When three minutes have passed after the LEV operates with initial opening, the LEV opening is adjusted every 1 minute to
keep the amount of superheat before and after the plate heat exchanger constant.
(2) Heating-only Thermo-ON
When three minutes have passed after the LEV operates with initial opening, the LEV opening is adjusted every 1 minute to
keep the amount of subcool before and after the plate heat exchanger constant.
(3) Cooling-main/Heating-main Thermo-ON and Cooling-main/Heating-main refrigerant recovery
1) Periodic control for LEV1
The LEV opening is adjusted the same way as described in (2) Heating-only Thermo-ON and Heating-only refrigerant recov-
ery.
2) Periodic control for LEV2
To be fully open (3000)
26
- chapter 5
Always ON during heat recovery de-
frost
SV1
Always ON
Always OFF
Always OFF
Always OFF
OFF except to perform heat recovery
defrost
Always OFF
Always ON
Always OFF
Always ON
Always ON
BS_05_M