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For boilers with a capacity more than 300kW; high pressure protection system
must have at least 1 pressure limit switch (pressure switch) as well as relief
valve. This switch must be tripped before the pressure relief valve and lock the
burner and/or the fuel line by disabling them. The pressure switches should not
have automatic reser function and should not automatically reset itself even if
the pressure drops and falls within the normal range.
The pressure limit switch is not included in the standard equipment supplied
with the boiler. It is the responsibility of the project and assembly units to
properly connect the pressure limit switch with manual reset with the correct
diameter and ampere value to the system. Pressure limit switch and pressure
relief valve can be connected in series to a collector to be installed on a line
from the connection point below the boiler water flow flange, without any cut-off
valve.
Protection against low water level/pressure;
Closed expansion systems must be protected against operation at low water
level. The heat transfer surfaces of the hot water boilers that continue to
operate at low water level can overheat and the boiler may become vaporous,
which is a danger that could cause boiler explosions. Low water level protection
methods include low pressure switch, water flow switch, water level switch. The
low water level controller is not included in the equipment supplied with the
boiler and the project and assembly units are responsible for the selection and
installation of the equipment.
Closed expansion tank;
In closed heating systems, the water which is in the system as the heat carrier
tries to expand and increase inherently when heated, this causes the pressure
increase due to the fact that there is no volume change in closed systems. In
closed heating systems, an expansion tank capable of meeting this increase in
volume and holding at least a certain amount of reserve water must be
connected to the system. In the system which is widely used today, the closed
expansion tanks with membrane perform this function. EN 12828 standard can
be used when selecting closed expansion tanks with membrane type, but
manufacturers' selection calculations and installation criteria of closed
expansion tanks with membrane are prioritized.
In the case of water expansion at the highest possible temperature in the
system, the expansion tank volume and the size of the connecting pipe to the
boiler should be selected so as not to increase the system pressure (without
activating the pressure limit switch and relief valve). When installing the
expansion tank, frost protection should be considered. It is recommended to
connect the expansion tanks with membrane to the connection near the boiler
return water flange. Manual shut-off equipment must not be used in the
connection line between the expansion tank and the boiler. Only for the
purpose of maintenance, repair, pre-gas pressure control of the expansion
tank, it is appropriate to use lock-type valves