Hitachi YUTAKI Series - Freeze Protection; Restart after Power Failure

Available Optional
functions
Service Manual
152
Restart after power failure
SMGB0066 rev.0 - 12/2009

Using setting point =1. The unit is controlling the pump in order to avoid water circuit freeze as the following graphic
indicates:
Intermitent 5’ ON / 50’ OFF
Permanent
Ambient temperature (Ta)(ºC)
Yutaki water
temperature
(Tw)(ºC)
Wheninoperationinwinterintheoutdoorairtemperatureat2ºCorlower,thewaterpumpoperatestoprotectYutakiunit
fromfreezing.Whentheoutletwatertemperatureis15ºChigher,thepumpperformswithoutinterruptions,i.e.,runsforve
minutesandstopsfor55minutes.Thesegmentdisplaysshows“PU”whenthepumpisrunningforveminutes,and“88”
when at stop for 55 minutes. This control is released when the outdoor temperature becomes 4 ºC or higher.
Winter antifreezing control (pump intermittent operation) becomes inactive when OFF is selected in the setting mode. When
runoperationisperformedduringthiscontrol,releasethecontrolandrunthepump.
The winter antifreezing control is not performed in any abnormality such as when wiring of outlet water thermistor or outdoor
air thermistor is broken or short-circuitted (Alarm display “12” or “22”). The pump turns off after 10 seconds following the
fulllmentofwinterantifreezingcontrolreleaseconditions.

Jumper JP2 forces the unit to maintain the status before the failure.
Iftheunitwasrunning,oncethepowerisrecoveredtheunitwillrunagain.Ontheotherhand,iftheunitwasstopped,itwill
remain stopped.