Dhw Piping - Hitachi YUTAKI S80 Series Installation And Operation Manual

WATER PIPING
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Hydraulic optional elements
In case of a recirculation circuit for the DHW circuit:
• 1 Recirculation pump (field supplied): this pump (3) will help to
correctly recirculate the hot water to the DHW inlet.
• 1 Water check valve (ATW-WCV-01 accessory): this Hitachi
accessory (2) is connected after the pump (3) in order to en-
sure the non-return of water.
• 2 Shut-off valves (field supplied): one (4) before the pump (3)
and one (4) after the check valve (2) in Shut-off valve (field
supplied).
N O T E
lf the domestic cold water entry pressure is higher than the equip-
ment's design pressure (6 bar), a pressure reducer must be fitted
with a nominal value of 7 bar.
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Recommendations for the DHW hydraulic circuit
• Connect all pipes as close as possible to the unit, so that dis-
connection can be easily performed when required.
• It is recommended to use flexible joints for the water piping
inlet and outlet in order to avoid vibration transmission.
• Apply thermal insulation on the hydraulic system pipes in or-
der to avoid accidental injure due to excessive heat on piping
surfaces and also to avoid heat losses.
• Proper water pipe inspection should be performed after pip-
ing work to assure there is no water leakage in the circuit by
completely opening the DHW inlet and outlet shut-off valves.
• The heating coil of the tank is placed in a highest position
than the indoor unit air purger. Then, to totally purge the space
heating circuit, it is very important that the heating coil of the
tank will be fully air purged.
• The indoor unit is equipped with an air purger (factory sup-
plied) at the highest location of the indoor unit. If this location
is not the highest of the water installation, air might be trapped
inside the water pipes, which could cause system malfunc-
tion. In that case additional air purgers (field supplied) should
be installed to ensure no air enters the water circuit.
• When the unit is stopped during shutdown periods and the
ambient temperature is very low, the water in the pipes and
the circulating pump may freeze, thus damaging the pipes
and the water pump. In order to prevent this, the unit has a
self-protection mechanism which should be activated (refer to
Optional functions chapter of the Indoor unit Service Manual).
• Fresh water must circulate inside the DHW tank water circuit
at least one time per day during the first days after the instal-
lation has been performed.
• The storage capacity of the tank has to meet with the daily
consumption in order to avoid stagnation of water.
• Try to avoid long runs of water piping between the tank and
the DHW installation in order to decrease possible tempera-
ture losses.
• Insure that the installation, testing and applied materials com-
ply with applicable legislation.
19 PMML0291A rev.2 - 09/2014

5.1.2 DHW piping

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Water pipes connection
Indoor unit connections
The DHW connections of the indoor unit are located where it is
visible in the following images:
3-way valve
3-way
valve motor
(upper part)
Metal plug
3-way valve
connection for
heating coil inlet
3-way valve connection for
heating coil inlet
(Left side view)
T-branch
Metal
T-branch
plug
connection for
heating coil outlet
T-branch connection for
heating coil outlet