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Safety devices
Safety
Installing safety valves
Every heat producer in a heating system must be
protected by at least one safety valve against
pressure exceeding the maximum permissible
operating pressure (see EN 12828). These valves
must be designed such as to ensure the maximum
permissible operating pressure that can arise in the
heating system or parts thereof. The safety valve must
be situated in the boiler room and be easily accessible.
Fig. 6-6: Safety valve
DANGER!
Do not install any shut-off valves, strainers or such like
between the boiler and the safety valve.
The connection size of the safety valve is determined
on the basis of the heating system's maximum heating
capacity, as shown in the table.
Install the safety valve at the highest point of the heat
producer or in the flow pipe close to the heat producer.
Only in this way can it discharge heat by blowing out
hot water and steam.
The safety valve may be installed in any position, but
the upper part of the valve must not face downward.
The flow pipe may be 1 m long maximum and must be
routed in a straight line in the nominal diameter of the
valve inlet.
The safety valve must be installed on the boiler flow. A
connection is already available for this purpose.
Fig. 6-7: Connection for safety valve on flow
DANGER!
Safety valve outlet
The safety valve outlet must be directed to the ground
in a pipe so nobody is endangered by hot water or
steam.
The safety valve outlet (vent pipe) must have at
least the same nominal diameter as the valve
outlet, be installed with a consistent gradient and
be routed to a sewage system (e.g. duct). The vent
pipe may contain a maximum of 2 bends and be
2 m long. If a length of more than 2 m is required,
the next size of pipe must be selected. More than
3 bends and 4 m of length are not permitted. The
mouth of the vent pipe must allow easy inspection
and be routed such as to exclude any danger to
persons. If the vent pipe ends above a funnel, its
discharge pipe must have a cross section at least
double that of the valve inlet.
Shutdown by the safety temperature limiter (STB)
The heat exchanger and combustion chamber is each
equipped with its own safety temperature limiter as
additional protection against boiler overheating. If a
temperature of 105°C (tolerance 100 to 106°C) is
reached, the safety temperature limiters cut off the flow
to the draught fan and stop the fuel feed. An alarm
message appears on the screen. If the temperature
Valve size
a
Nominal diameter (DN)
a. The valve size is determined by the size of the inlet
connection.
Maximum heating ca-
pacity (kW)
15 (G ½)
50
20 (G ¾)
100
25 (G 1)
200
32 (G 1 ¼)
300
40 (G 1 ½)
600
50 (G 2)
900
