HDG Navora 20, Operation Manual

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4 Planning and installation – Electrical system
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4.8 Electrical system
The electrical connections must be made in accordance with DIN IEC
60364 “Setting up low-voltage electrical installations”.
✎
The technical details are described in chapter “3 Mode of
operation”, section “3.3 Technical data”.
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The circuit diagram is enclosed with the supplied documentation.
This is created based on the system selected.
4.9 Water
Before putting the system into operation, the pressure of the
diaphragm expansion vessel must be adjusted for the conditions in
the heating system and in the building.
After putting the system into operation, heat up the system to the
maximum boiler temperature and bleed air from the system again to
make sure that there are no air pockets.
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 normal 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.
Important!
The heating system must be filled with water in accordance with
VDI guideline 2035, “Avoiding damage in hot water heating
systems”.
Mains-dependent, stand-alone supply systems are not safe enough
due to dependence upon the power supply!