Hitachi RAF-25NH4 Données Techniques page 135

AUTO FRESH DEFROSTING
¥ If auto fresh conditions are established when heating operation stops, defrosting operation can be executed during the stop period.
Auto fresh defrosting consists of [balancing period of 90 seconds when defrosting starts
(1) Auto fresh defrosting defrosting start conditions
¥ Auto fresh defrosting is performed when all the following conditions are satisfied:
Heat-exchanger at low temperature (heat-exchanger temperature
1)
2) Units in all cycles stop
3) Auto fresh defrosting inhibit time (15 minutes) is up
4) Compressor is turned on during operation stop
5) There is a delay of compressor from indoor units during operation stop
(2) Auto fresh defrosting stop conditions
¥ Auto fresh defrosting is released when any of the following conditions is established:
Heat-exchanger temperature is recovered (heat-exchanger temperature
1)
2) Maximum defrosting time (12 minutes) is up
3) A failure occurs
4) Either indoor unit of all cycles starts operation.
※ Release during balancing at start: To stop or start operation when remaining balancing time is up.
Release during reverse cycle period: To stop or start operation when balancing time (3 minutes) is up.
(3) Outputs during auto fresh defrosting
[Defrosting request between outdoor microcomputers] Not to be transferred.
[Indoor defrosting request] To be transferred only to object unit of auto fresh defrosting (indoor unit which has stopped last).
[Compressor] To increase the speed at the rate of DFSTEP rpm/TDFSPT second and reach the maximum defrosting speed [DEFMAX].
[Expansion valves] Non-object units of auto fresh defrosting: To be fully closed when defrosting starts and the balancing time (30 seconds) is up.
Object units of auto fresh defrosting: To be opened by [DFSPPS] pulses, synchronized whith a step-up of rotation speed, and fully opened
[DFPSMX] when the speed reaches [DEFMAX].
(4) Special remarks
¥ Other cycles should remain in the stop mode.
¥ When operation stops during defrosting, the unit should directly shift to auto fresh defrosting.
¥ All indoor units should stop for auto fresh defrosting. Therefore, if two cycles stop operation simultaneously, auto fresh defrosting will not
commence because of delay in communications.
Defrosting signal
Defrosting request between
outdoor microcomputers
Main unit 1
Main unit 2
Sub unit 1
Sub unit 2
Main unit 1
Main unit 2
Sub unit 1
Sub unit 2
Unit 1
Unit 2
Turns on
for cooling
Turns on
for heating
Cooling output
Heating output
Outodoor fan
Auto fresh inhibit period 15s
WMAX2
Compressor
rotation speed
520
480
Unit 1
0
520
480
Unit 2
+100rpm
0
¥ See other sections for details of expansion valve TD control, ÆN correction and distribution control.
※
¥ TSKTM1, SDRCT1, DFSTEP, TDFSPT, DEFMAX, DFCTPS, DFSPPS, DFPSMX and PCLLOSH are EEPROM data.
15s
Balancing period of 90s
WMAX1
60s 30s
Hold
Hold PCLOSH
→ reverse cycle period for 12 minutes maximum]
)
≦ DEF → ON
≧ DEF → OFF
Defrosting request
Reverse cycle period (max. 12 minutes)
30s TSKTM1
Defrosting sequence
DFSTEP min
TDFSPT sec.
SDRCT1
DFSPPS pulse
Hold
DFCTPS
Hold
154
)
Balancing period of 3 minutes
DEFMAX
-1 /
DFPSMX
.
Balancing request
Balancing request
30s
80s