Technical data
Technical documentation 
Technical documentation
STZS ed 06/03
8
ZEUS SUPERIOR
HYDRAULIC CIRCUIT 
SECONDARY CIRCUIT (D.H.W. CIRCUIT) 
The domestic hot water circuit is engaged every time the water contained in the storage tank and 
measured by means of the d.h.w. NTC sensor (4) has to be restored to the desired temperature. 
This occurs when domestic hot water is used and to restore the losses due to thermal dispersion. 
- OPERATION 
Following a d.h.w. request, the modulation board starts the boiler pump (7) and powers the 
motor of the electric 3-way valve (8). 
The consequent movement of the valve to domestic hot water position (see 3-way electric valve 
operation), closes the system return pipe (R) and, at the same time, opens the return pipe of the 
storage tank coil (4). 
This way, circulation is allowed in the coil (4) which, through its walls, enables the cold 
domestic water to absorb the heat contained in the primary circuit water. 
In this phase, the central heating function is disconnected as the production of d.h.w. has 
priority. 










