Hitachi YUTAKI Series - Heating Circuit (Secondary) Pump; Automatic No-Load Function; DHW Control Functions; DHW Storage Tank Loading

85
DHW control functions
SMGB0066 rev.0 - 12/2009
Controller pack
Service Manual
4
 

Whentheheatingcircuitisenabled,thesecondarypumpwillbeswitchedon.Whentheheatingcircuitisdisabled,the
secondary pump is switched off after a pump overrun time.
Ifthescreedfunctionisactivatedorsystemfrostprotectionisactive,thesecondarypumpcontinuestorun.
IfthesystemusesaDHWdivertingvalveandDHWstoragetankloadingisactive,thenthesecondarypumpcontinuesto
run,sinceitisalsousedfortheDHWloading.

P2 Secondary Pump Selection (default 0 – no secondary pump)
P3 Pump Overrun Time (default 2 min)

CONF1,2: IfabuffertankorhydraulicseparatorisusedbetweentheHeatPumpandtheheatingcircuit,itis
necessary to set parameter P2=1 to enable control of the secondary pump.
CONF3,4,5: Secondarypumpcontrolisalwaysenabled.
CONF4,5: Ifthemixedcircuitmaximumtemperaturelimitisactive,thenthesecondarypumpisswitchedoff.
 

When the calculated supply temperature setpoint (from OTC heating curve + room setpoint shift + room compensation
shift)islessthantheroomtemperature,thentheheatingcircuitcanbeswitchedofftosaveenergy.Aswitching
differential of +/- 1K is applied.

OTC supply setpoint < room temperature (TR1) – 1K => No-Load condition is active
OTC supply setpoint > room temperature (TR1) + 1K => No-Load condition is not active.
WhentheNo-Loadconditionisactive,theheatingcircuitisswitchedoff.

P30 No-Load Function enable/disable (default 1)
= 0 disabled
= 1 enabled

 

TheDHWcontrolfunctionisavailableforcongurationsCONF1,2,3,and5.

ToenableDHWcontrol,parameterP1shouldbesetaccordingtowhetherthesystemusesadivertingvalveorseparate
pump for the DHW circuit.