Hitachi YUTAKI S Series Installation And Operation Manual page 59

◆ Water pump 3 (Default for Output 2)
When the boiler is configured with the heat pump or needs an additional pump for the system, a
hydraulic separator or buffer tank must be used to ensure a correct hydraulic balance
Auxiliary boiler or heater (Default for Output 3)
◆
The auxiliary boiler or heater can be used when the heat pump cannot achieve the require
temperature by itself.
◆ Solar (Default for output 4)
This output is used when solar mode is enabled (from Unit controller) and the temperature in
the solar panel rises above the water temperature in the domestic hot water tank (DHWT). The
connection between terminals 39 and 40 shall be closed in order to activate the dedicated water
pump for solar panel combination.
PMEN0643 rev.0 - 04/2023
34 36
(L)
(N)
M
Water pump III
(Output 2)
37 38
Free
contact
Auxiliary
Heat
39 40
Solar (out)
(Output 4)
6
50