4 Planning and installation – Connecting the thermal safety device
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4.10 Connecting the thermal safety device
In accordance with DIN EN 12828, heating systems must be
equipped with safety devices to prevent the maximum operating
temperature from being exceeded. The safety heat exchanger serves
to protect the boiler against overheating and may not be used for
other purposes (i.e. as a regular heat exchanger). If the heat transfer
capacity is suddenly lost (for example, if the circulation pump for
raising the return temperature fails), heat production cannot be
stopped as quickly as with an oil- or gas-fired boiler. When the
maximum operating temperature is exceeded, the thermal safety
device (TAS) is triggered and cold water flows through the safety
heat exchanger. The resulting excess energy is thus dissipated by this
“emergency cooling”. (This is an alternative to fast regulation.)
However, the safety heat exchanger and thermal safety device can
only serve their purpose if the following requirements have been
met:
•
A flow pressure of at least two
bar must be available at the cold
water inlet of the safety heat exchanger.
•
The distance between the supply and return lines of the thermal
safety device and the safety heat exchanger should not be less
than their nominal width. The supply line may not be equipped
with a shut-off valve.
•
Water must be able to flow freely through the system.
•
The flow pressure at the flue pipe connection on the boiler may
not significantly exceed the prescribed value.
The thermal safety device must be installed according to guidelines
from HDG Bavaria.
Because they depend on the mains power supply, mains-
dependent stand-alone supply systems are not sufficiently reliable
and are not permitted!
The TAS must be inspected annually by a qualified technician to test
that it is working properly.
Important!
In order to prevent leaks, avoid turning the connections of the
safety heat exchanger anticlockwise when installing the thermal
safety device.
