Si33-105 Outline of Control (Outdoor Unit) < Symbols using in this manual >
Function R407C PLUS Series Heat Recovery System 57
3.3.2 4-Way Valve Changeover Ensuring Control
Purpose
!
To ensure the changeover 4-way valve, when difference in high and low pressure does not
generate due to mid-stop of the 4-way valve in each startup mode, increases the circulation
amount of compressor and forcibly generates the differential pressure with pressure loss in
the 4-way valve.
Contents
!
Varies the compressor loads under the following conditions in all startup control, 4-way valve
changeover control, and equalizing control.
Computes Pc-Pe every 10 seconds when 20 seconds elapsed after the control turns on, and
varies the compressor operation steps depending on the computed value.
When the following condition is met, conducts step down.
When stepping down, the lower-limit frequency is to be as follows.
At the normal startup of cooling and heating operation
Within 1 minute after startup : 41Hz + OFF + (OFF)
Elapsed time of 1 minute after startup : 52Hz+OFF+(OFF)
At the startup of 4-way valve changeover
41Hz + OFF + (OFF)
At the (startup of) pressure equalizing
41Hz + OFF + (OFF)
In any cases, fix the frequency in the initial compressor operation step at 41Hz + OFF +
(OFF).
Pc-Pe<0.196MPa
10-sec. timer counts up
Current compressor operation step + 3
However, the upper-limit frequency should
be 41Hz + ON + (OFF)
&
(V2564)
Pc-Pe>0.39MPa Current compressor operation step – 3
(V2565)
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