In a building with hot water circulation, it is easy to think the job is done once hot water comes out of the tap. But the temperature has to be held throughout the system, including the long branches and the furthest risers. Otherwise water sits at low temperatures, which is bad for both hygiene and the energy bill.
Why the circulation temperature matters
- Hygiene: Legionella and other bacteria thrive in lukewarm water. When circulation keeps the temperature up throughout the installation, the risk is reduced.
- Energy: If the circulation is not balanced, too much water flows through the short branches while the long ones get too cold. The water heater and circulation pump then have to work harder than necessary.
- Comfort: Users should not have to wait long for hot water, wherever in the building they open the tap.
How Aquastrom works
Oventrop’s Aquastrom valves have been developed specifically for potable water circulation. They sit in the circulation pipe and regulate the flow thermostatically:
- Holds the set temperature. If the temperature drops below the set value, the valve opens and increases the flow of hot water. Once the temperature is reached, it throttles back again.
- Setting range 50–65 °C. Oventrop recommends 55–60 °C, and the valves are preset to 57 °C.
- Residual flow. The valve maintains a fixed minimum flow, so the branch never stands completely still.
- Thermal disinfection. The valve automatically recognises thermal disinfection and opens, so the hot water reaches the whole system.
- Lead-sealable. The temperature setting can be locked, so it is not changed by accident.
The valves have a bronze body, and all parts in contact with potable water are free of brass. They come with an insulation shell and thermometer. On selected models a temperature sensor can be retrofitted for remote monitoring.
From design to installation
Oventrop points out that choosing the right components makes a significant difference to how the complete system performs, from design and specification through to installation. Aquastrom is designed to the German DVGW codes of practice W551 and W553 for balancing potable water circulation.
For the installer, that means fewer readjustments and a system that holds its temperature, even when consumption changes.
Where does it make sense?
- Apartment buildings and housing associations with long circulation branches.
- Institutions, hotels and sports halls, where potable water must be safe.
- Renovation of older systems, where the branches have never been balanced.
Oventrop at Arne Nielsen A/S
Arne Nielsen A/S distributes Oventrop. If you would like to know more about Aquastrom, or need valves for a specific installation, write to us at info@arnenielsen.com. See also our Oventrop page.
Sources: Oventrop product pages for Aquastrom VT and Aquastrom TB, and Oventrop UK on LinkedIn, 13 October 2026.