Hitachi YUTAKI Series - Heatpump Control Functions; Heatpump Control

91
Heatpump control functions
SMGB0066 rev.0 - 12/2009
Controller pack
Service Manual
4


P24 CongurationofTariff/TimerInput(default4)
  
0 Tariff/Timer input is ignored
1 Tariff/Timer input is used for Heat Pump blocking
2 Tariff/Timer input is used for Heat Pump blocking
3 DHW is blocked DHW is enabled
4 DHW is enabled DHW is blocked

note
The tariff/timer input can be used for DHW time switching OR Heat Pump blocking, not both -

 

The System Controller normally switches the heat pump on when there is a demand from the heating or the DHW circuit.
The Heat Pump on/off output of the System Controller is connected to the Remote on/off input of the heat pump.
Theheatpumpwillstartthewatercirculationpump(primarypump)whentheremoteon/offinputisswitchedon,and
enable its internal control of the compressor and heat pump system components.
The System Controller switches the heat pump off when :
theoutdoortemperature(TEXT)<-20°C(adjustable,see“HeatPumpoperatinglimits”)
or,thereturnwatertemperature>60°C (adjustable,see“HeatPumpReturnHighLimit”)
or,heatpumpblockingisactive (tariff/timerinput)

note
The compressor will not always run when the remote on/off signal is switched on by the System Controller. The -
Heat Pump has an internal control function “thermo-off” which will switch the compressor off when the target water
temperature is exceeded. The compressor will also be switched off when there is an internal heat pump fault.