Hitachi YUTAKI S COMBI Series Installation And Operation Manual

28
PMEN0645 rev.0 - 04/2023
5
WATER PIPING
REFRIGERANT PIPING
5.3.3 Requirements and recommendaons for the hydraulic circuit
• The maximum piping length depends on the maximum pressure availability in the water outlet
pipe. Please check the pump curves.
• The indoor unit is equipped with an air purger (factory supplied) at the highest locaon of the
Indoor Unit. If this locaon is not the highest of the water installaon, air might be trapped
inside the water pipes, which could cause system malfuncon. In that case addional air
purgers (eld supplied) should be installed to ensure no air enters the water circuit.
• For heang oor system, the air should be purged by means of an external pump and an open
circuit to avoid air bags.
• When the unit is stopped during shut-o periods and the ambient temperature is very low,
the water inside the pipes and the circulang pump may freeze, thus damaging the pipes and
the water pump. In these cases, the installer shall ensure that the water temperature inside
the pipes does not fall below the freezing point. In order to prevent this, the unit has a self-
protecon mechanism which should be acvated (refer to the Service manual, “Oponal
funcons” chapter).
• Check that the water pump of the space heang circuit works within the pump operang range
and that the water ow is over the pump’s minimum. If the water ow is below 6 litres/minute
,alarm is displayed on the unit.
• An addional special water lter is highly recommended to be installed on the space heang
(eld installaon), in order to remove possible parcles remaining from brazing which cannot
be removed by the indoor unit water strainer.
• When selecng a tank for DHW operaon, take into consideraon the following points:
✓ The storage capacity of the tank has to meet with the daily consumpon in order to avoid
stagnaon of water.
✓ Fresh water must circulate inside the DHW tank water circuit at least one me per day during
the rst days aer the installaon has been performed. Addionally, ush the system with
fresh water when there is no consumpon of DHW during long periods of me.
✓ Try to avoid long runs of water piping between the tank and the DHW installaon in order to
decrease possible temperature losses.
✓ lf the domesc cold water entry pressure is higher than the equipment’s design pressure
(6 bar), a pressure reducer must be ed with a nominal value of 7 bar.
• Ensure that the installaon complies with applicable legislaon in terms of piping connecon
and materials, hygienic measures, tesng and the possible required use of some specic
components like thermostac mixing valves, Dierenal pressure overow valve, etc.
• The maximum water pressure is 3 bar (nominal opening pressure of the safety valve). Provide
adequate reducon pressure device in the water circuit to ensure that the maximum pressure is
NOT exceeded.
• Ensure that the drain pipes connected to the safety valve and to the air purger are properly
driven to avoid water being in contact with unit components.
• Make sure that all eld supplied components installed in the piping circuit can withstand the
water pressure and the water temperature range in which the unit can operate.
• YUTAKI units are conceived for exclusive use in a closed water circuit.

Hitachi YUTAKI S COMBI Series Specifications

General

Type	Air-to-Water Heat Pump
Energy Efficiency Class (Cooling)	A++
Refrigerant	R32
Operating Temperature Range (Heating)	-20°C to 35°C
Energy Efficiency Class (Heating)	A+++
Integrated DHW Tank	190 liters
Dimensions (Indoor Unit)	Varies by model
Dimensions (Outdoor Unit)	Varies by model
Weight (Indoor Unit)	Varies by model
Weight (Outdoor Unit)	Varies by model
Operating Temperature Range (Cooling)	+10°C to +46°C