Fewer problems in DHW circulation systems Presentor Onno

Fewer problems in DHW circulation systems Presentor: Onno Leever

I’m passionate about DHW circulation systems

How my passion led to recommendations for DHW • Solved problems • Collected opinions • Approved for publication

Overview • When is a DHW circulation system necessary? • Single loop or multi-branch? • Airventing • Insulating • Balancing • Selecting a pump

Only use a circulation system when necessary • 20 seconds rule • Boiler-design in central position • Using more water heaters

Advantages of not using a circulation system • Saving energy • Less pipe • No insulation

Disadvantages of not using a circulation system • Waste water • Exploitation costs • Maintenance costs

How the systems works

Single loop or multi-branch • Simple building • Lower pressure drop • Connection order

Temperatures • Boiler temperature: 65°C (150°F) • Less scale: below 67°C (152°F) • Return temperature: 60°C (140°F)

Insulating • Lambda-rule: 0. 04 Watt/meter. Kelvin • Thickness-rule: 35 millimeter • Maximize waste per meter: 10 Watt/meter • Insulate valves, pumps, etc.

Venting DHW circulation systems • Let the flow be at least 0, 5 meter per second • Mount the pipe at a slight angle • Attach the pump upwards in a vertical pipe

Balancing • Static balancing • Thermostatic balancing

How to select a circulator • Select a pump based on the balancing method • Calculate the operating point • NPSH

Summary • • • 20 seconds rule Multi-branch when it leads to lower pressure drop Temperature drop 65 to 60°C or 150 to 140°F Lambda 0. 04 Watt/meter. Kelvin, thickness 35 mm Advise maximize 10 Watt/meter Use an automatic air vent Mount pipes at a slight angle Try to minimize the flow rate at 0. 5 m/s Attach the pump upwards in a vertical pipe Balancing: static or thermostatic NPSH

More You can reed more recommendations in my paper. If you have tips for me; Please connect me at a break Or send a message to Onno Leever on Linked. In

The end Thanks!