Danfoss MTCV DN 20, Version O — self-acting multifunctional thermostatic circulation valve for automatic thermal balancing of domestic hot-water (DHW) return risers. It throttles the circulation flow as the return-water temperature rises toward the set point, keeping every riser at the required temperature and reducing pumping energy and Legionella risk. Bronze (Rg5) body, Internal thread ISO 7/1Rp ½, PN 10, Kvs 1.8 m³/h, factory setting 50 °C, temperature setting range 35 °C to 60 °C, media temperature max 100 °C. Approval: ACSPZH. OEM P/N 003Z0553. EAN 5702421547274. Technical data quoted verbatim from store.danfoss.com (code 003Z0553).