Freeze Protection; Restart After Power Failure - Hitachi YUTAKI Series Service Manual

5.1. frEEZE ProTECTIon

Using setting point =1. The unit is controlling the pump in order to avoid water circuit freeze as the following graphic
indicates:
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 five
minutes and stops for 55 minutes. The segment displays shows "PU" when the pump is running for five 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
fulfillment of winter antifreezing control release conditions.

5.2. rESTArT AfTEr PoWEr fAIlUrE

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.
SMGB0066 rev.0 - 12/2009
152

Restart after power failure

Ambient temperature (Ta)(ºC)
Available Optional
functions
Service Manual
Intermitent 5' ON / 50' OFF
Permanent