Hitachi YUTAKI S80 Serie Manuel D'instructions page 32

MAINTENANCE
10.3 DRAINING
10.3.1 Heating coil circuit

Tank over the indoor unit
1 Switch OFF the main power supply of the indoor unit.
2 Close the 2 shut-off valves (field supplied) installed at the
space heating pipes (Water inlet and outlet connections).
3 Open the safety valve of the indoor unit manually. The water
will be expelled by its connected drain pipe and will be
driven to the base hole.
4 There will be a part of the water contained into the indoor
unit which may not be expelled through the safety valve.
Open the cap placed in the lower part of the water pump
piping in order to expel it.
5 Once all the water has been drained, close both safety valve
and cap.
!
C A U T I O N
Check that drain pipe for safety valve is correctly connected and placed
as far as possible from the indoor unit.

Tank beside the indoor unit
To drain the tank's heating coil water
1 Switch OFF the main power supply of the indoor unit.
2 Close the recommended 2 shut-off valves (field supplied)
installed between the heating coil pipes (connected to the
tank) and the flexible water pipes of the kit ATW-FWP-02
(connected to the indoor unit safety valve and T-branch).
3 Disconnect the 2 heating coil pipes (connected to the tank)
from the shut-off valves (field supplied) to expel the water
contained into the heating coil of the tank.
To drain the indoor unit water
Follow the same procedure explained in
unit", and finally, disconnect the 2 flexible water pipes of the kit
ATW-FWP-02 (connected to the indoor unit safety valve and
T-branch) from the shut-off valves (field supplied) to expel the
remaining water in these pipes.
!
C A U T I O N
• Take care when draining the water of the tank's heating coil and the
remaining water of the kit ATW-FWP-02 (connected to the indoor
unit safety valve and T-branch). Perform the draining work as far as
possible to the indoor unit.
• The expelled water could be hot and could keep in pressure. Take
care with this draining.
24 PMML0344B rev.2 - 01/2021
10.3.2 DHW circuit
For the draining process of the DHW circuit it is highly
recommended to provide to the installation with the elements
explained in section
elements for DHW". The installation of those elements ease the
process of the DHW tank drain. Whether installed, proceed as
explained below:
1 Switch OFF the main power supply of the indoor unit.
2 Close the main DHW inlet valve (recommended shut-off) in
3 Close the shut-off valve of the DHW outlet (field supplied).
4 Open manually the drain valve (Additional recommended
5 When the water begins to drain more slowly, disconnect the
6 Continue with the draining process until the tank has been
!
When disconnecting the DHW outlet pipe from the shut-off valve, the
expelled water could be hot and could keep in pressure. Take care with
this draining and perform this work as far as possible to the tank.
"Tank over the indoor
"4.1.1 Additional hydraulic necessary
order to avoid the tank filling.
accessory)
DHW outlet pipe from the shut-off valve. By this way, the air
enters to the tank and helps to the draining process.
fully emptied of water.
C A U T I O N