Hitachi YUTAKI Series Service Manual

103
General functions
SMGB0066 rev.0 - 12/2009
Controller pack
Service Manual
4

Withsomeboilers,especiallyoilboilers,thereisariskofunwantedliquidcondensationonthegassideoftheboiler
heat exchanger if the temperature falls below the water condensation temperature. This can cause reduced boiler life. In
thesesituations,itisdesirabletoallowtheboilerheatexchangertowarmupbeforetheheatingcircuitwateriscirculated
through the heat exchanger. This function prevents the mixing valve opening until after the boiler has been switched on
for a set period of time (parameter P35).
The recommended setting will depend on the size and type of boiler. (delay time can be set between 1 and 20 minutes).

P35 Mixing Valve Opening Delay Time (default OFF)

note
If P35 is set to OFF, this function is disabled. -

 

The System Controller has a frost protection function to help prevent the heating system pipe-work freezing. When the
actualoutsidetemperaturefallsbelowtheparameter(P22),thesupplywatertemperaturewillbemaintainedatleastat
the parameter value (P21). A switching differential of 1K is applied.
Outside temperature (TEXT) < P22 Supply Setpoint (SSUP) determined by heating or DHW demand but always >= P21
Outside temperature (TEXT) > P22+1K Supply Setpoint (SSUP) determined by heating or DHW demand.

P21 Frost Protection minimum Supply Temperature (default 20°C)
P22 Frost Protection Activation Temperature (default 2°C)

Todisablethesystemfrostprotectionfunction,setP22=OFF.
 

At higher outside temperatures it doesn’t make sense to keep heating the building. The System Controller will switch
the heating off when the average daily outdoor temperature (averaged over 24hrs) rises above the parameter (P26). A
control differential of +/-0.5K is applied.

Average Outside Temperature > P26 Summer Switch-Off condition is active.
Average Outside Temperature < P26-0.5K Summer Switch-Off condition is not active.
WhentheSummerSwitch-Offconditionisactive,theheatingisswitchedoff.

P26 Summer Switch-off Temperature (default 20°C)

Todisabletheautomaticsummerswitch-offfunction,setP26=OFF.

Hitachi YUTAKI Series Specifications

General

Heating Capacity	5.0 kW - 16.0 kW
Cooling Capacity	5.0 kW - 16.0 kW
Energy Efficiency Class	A+++
Refrigerant	R32
Operating Temperature Range (Cooling)	46°C
Noise Level (Indoor Unit)	45 dB
Noise Level (Outdoor Unit)	45 dB