Defrost (Only Air-Cooled Heat Pump Type) - Hitachi RCUE40AG2 Service Manual

Control System

Defrost (only air-cooled

4.16. Defrost (only air-cooled heat pump type)

heat pump type)
pag. 72
SMGB0003 rev.0-01/2007
Ambient temperature, evaporating temperature and evaporating pressure are detected
during heat operation to detect the frost volume. By the changeover of 4 way valve,
reverse-cycle defrosting is performed.
Defrosting start conditions

2 min from starting unload
Compressor operation >
designed time (limitation of
defrost interval)*
Evaporating temp≤-6 ºC
(air side HE inlet refrigerant)
(ambient temp) - (evaporating
temp) ≥ ambient temp corrected
value (detection of frost vol.)
Low pressure Ps ≤ 0.1MPa
Manual defrost SW ON
Not during defrost operation
Defrosting is performed for 6 minutes at longest. (automatic stop when all frost is
−
taken out).
In case that all frost is taken out very quickly, the period till next frost is extended
−
automatically in order to avoid too much defrost.
Warm water outlet temperature is lower than inlet temperature due to the reverse
−
cycle defrost.
(*) Normal: 55min. At longest: 115min.
AND
AND
OR
AND
Defrost