Instruction manual
PrimoBox ACB 910 mixing unit for condensing boilers
15
6.3.2
Connection of individual heating circuits
(direct circuit and mixing circuit)
The connection between the ACB unit and the heating system is made
via supply and return connections with female
G¾” threads located
at the bottom of the ACB unit. The maximum length of underfloor
heating pipes, resistance of flow, as well as the flow of medium by the
circuit with mixing must comply with the permissible values of flows
and resistances according to the chart presented in subsection 4.2.
6.4
Differential pressure relief valve DU
In a direct circuit with thermostatic valves
or zone valves, it is necessary to use
a pressure
differential
bypass
valve
(bypass). It is designed to maintain
a constant
pressure on the boiler pump,
which also works as a direct zone (radiator
zone) circulation pump. Recommended
DU
valve
setting
is
0.1-0.2
bar
overpressure.
Fig. 8: Differential pressure relief valve AFRISO DU
If the direct installation is characterized by high hydraulic resistance
and the relief valve opens too early (not allowing for adequate flow
on the radiator furthest away from the heat source) the setting should
be increased to 0.2-0.3 bar.
If thermostatic valves are not installed in the direct circuit next
to the radiators and no zone valves are used, set the differential
pressure relief valve DU to 0.5 bar overpressure.
6.5
Electrical connections
Make sure that the power supply has been disconnected and
protected against accidental switching on.
Comply with the accident prevention regulations and other rele-
vant accident prevention regulations.
The ACB mixing unit for condensing boilers is connected to 230V AC.
The ACB mixing kit has a built-in electrical box. During assembly
there is only a need to connect the pump and actuator dedicated ca-
bles to the electrical box. The connection between the electrical box
and the pump and actuator is already made at the factory.
