4
Installation
The ThermoBloc™ boiler protection recirculation and distribution unit can be installed on both
sides of the boiler following the flow directions indicated on the body. Installation is recommended
on the return to the boiler in mixing mode, in vertical postion (axis of the pump horizontal and
the axis of the thermostatic sensor vertical). This allows for the proper functionality of the natural
circulation flapper check valve. Separately purchased ball valves (Caleffi code NA39753- 1” FNPT
or NA39588- 1–1/4”
FNPT) installed on
each inlet and the
mixed flow outlet are
highly recommended
for isolation and
maintenance.
Natural circulation flapper check valve
The flapper check valve allows the natural thermosyphon circulation
of the system heat transfer fluid when the pump stops running
due to power failure. When the pump is running under normal
conditions the thrust of the flowing medium keeps the flapper
closed, forcing flow past the thermostatic sensor. When the pump
stops running and the fluid in the boiler is at high temperature,
natural circulation begins, by-passing the thermostatic sensor,
preventing over heating in the boiler.
Flapper check valve – lock
Before installation, remove the screw that
keeps the flapper check valve closed.
This screw is factory-installed to prevent
breakage during shipment. Removing the
protective screw ensures full functionality
of the flapper check valve as a natural
circulation device. To do this, unscrew the
union located on the mixed water outlet
port (to boiler) and access the screw
inside the valve body, unscrewing it using
a phillips head screwdriver.
BO IL ER
BO IL ER
