Continuous Heating Mode Control - Mitsubishi Electric HP120TNU-A Service Handbook

[5-2 Outdoor Unit Control ]
5-2-8

Continuous heating mode control

(1) Continuous heating mode start conditions
Continuous heating mode will start when all the conditions listed in the table below are met (outside temperature, cumulative
compressor operation time, and piping temperature).
However, even when the conditions are met, after the maximum number of consecutive continuous heating operation shown
below is performed, the reverse defrost operation will be performed one time.
Outside temperature
(TH7)
Cumulative compressor
operation time
Piping temperature
(TH3)
Maximum number of consecutive continuous heating operations
7 times
(2) Valve operation during Continuous heating cycle
1) When Single unit
Continuous heating operation is performed in the order shown below.
On a single unit model of HP72-HP144, defrosting is performed on the front and rear heat exchangers separately. Operation
patterns are shown in the table below.
Front HEX defrosting
Outdoor unit fan 1
Outdoor unit fan 2
SV1a
SV2
LEV2a
LEV2b
LEV2c
LEV2d
21S4a
21S4b
21S4c
HWE18220_GB
Single unit
1.0°C [33.8°F] TH7 < 7.0°C [44.6°F]
When 50 minutes have passed
TH7 10°C [50°F] < TH3 < 2.0°C [35.6°F]
Rear HEX defrosting
Stopped Stopped
Stopped Stopped
OFF
OFF
200
1500
-
6000
OFF
ON
-
Combination units
-5.0°C [23.0°F]
When 50 minutes have passed
TH7 10°C [50°F] < TH3 < 2.0°C [35.6°F]
3000
400
20
ON
OFF
TH7 < 7.0°C [44.6°F]
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