TÜV/CE safety valves for heating and cooling
Series 451bH

Rueckruf EN

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Safety valves with bellows made of stainless steel,angle type with threaded connections

For demanding requirements in hot-water and heating-systems, there is also a version available made of high-quality corrosion- and acid-resistant stainless steel. This valve is suitable for all hot- water systems, where protection cannot be achieved by using a standard safety valve with diaphragm with the standard set pressures of 2,5 or 3 bar, for example in the case of all large building complexes.

  • Examples of use
  • Approvals
  • Downloads

For the protection of:

  • thermostatically protected closed-circuit water heating systems with flow temperatures of up to 120°C for all static heights or rated output above 350 kW according to TRD 721, DIN 4751 and  DIN EN 12828.
    Should the thermostatic limiting and control unit fail, the safety valve has to blow-off the total heating output of the boiler as hot water and steam.
  • Closed-circuit solar heating plants according to  DIN 4757-1 and 2 with flow temperatures up to 120°C for all static heights.
  • district heating sub-stations, district heating building substations and domestic systems suitable for connection to a hot water district heating network according to DIN 4747-1 and AGFW 505.
  • heating plants for building technology and industrial applications
  • co-generation plants (CHP)
  • biogas plants
  • district heating transfer stations, building sub-stations
  • solar plants

Safety valves are set and sealed at the factory.


TÜV Type test approval 665

EU type examination

TR ZU 032/2013 - TR ZU 010/2011

TRD 721
AGFW 505
DIN 4751 Part 2
DIN 4747 Part 1
DIN 4757 Part 1 and Part 2
DIN EN 12828
DIN EN ISO 4126-1
PED 2014/68/EU

Suitable for
Stainless steel
1/2" - 2"
- 10°C to + 120°C
0,5 - 25 bar
Data sheet/Capacity table