Electric boilers MINI BTH Installation & Operating Manual (Revision: May 2015), 7
Figure 4 : Typical installation on high temperature application
3.4.1 Flow check valve
If the heating system includes a single pump,
without motorized zone valve and that the
heating distribution system is located above the
boiler, a flow check valve must be installed on
the supply distribution piping system to eliminate
hot water to flow by gravity in the heating
distribution piping when there is no heat
demand. As an alternative, a circulating pump
incorporating a spring check valve could be
used.
On heating systems having more than one
pump, each pump will need to be equipped with
a flow check valve either incorporated into the
pump or separated.
On heating systems with motorized zone valves
this component is not required because the
valve stops all water flow when closed.
3.4.2 Pressure relief valve
This component supplied with the unit must be
installed directly to the boiler housing to the
appropriate connection according to the
mounting position.
Connect the outlet of the relief valve downward
to a safe location in case of discharge.
The piping diameter used for the discharge
piping shall not be smaller than that of the valve
outlet. . No valve of any type, restriction or
reducer coupling should be installed on the
discharge line. Local codes shall govern the
installation of relief valves.
3.4.3 Expansion tank
The expansion tank must be able to store the
required volume of boiler water during maximum
operating temperature. The maximum allowable
operating pressure is 30 psi (207kPa). Contact
your installing contractor, plumbing supply
house, or local plumbing inspector for
assistance.
3.4.4 Water pressure regulator
The boiler should be installed in such a way that
it can be automatically be fed with water in the
event of a pressure drop (local regulation should
be applied).
The minimum pressure obtained when the
system is cold is generally 12 psi (83kPa).
This accessory shall be equipped with one or
more check valves to avoid all possibilities of the
boiler water returning to the potable water
supply network (local regulation should be
applied).
3.4.5 Air eliminator
Installation of manual or automatic air vents are
required to eliminate all air from the boiler and
the heating distribution system.
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