Written by IAPMO 12:45 pm ASSE, Backflow Prevention

ASSE International Publishes New Listing Evaluation Criteria (LEC) for Proportional Flow Control Devices, with Protection from Cross Contamination via Hydronic Water

ASSE International has published a new Listing Evaluation Criteria (LEC) document — ASSE LEC 2010-2020, Proportional Flow Control Devices, with Protection from Cross Contamination via Hydronic Water, for Use in Drinking Water Installations.

ASSE LEC 2010 devices control the flow of potable water based on the pressure of hydronic water from a hydronic system. The device performs this hydraulically and has integral cross-contamination protection between the potable and hydronic water. Proportional flow- control devices are typically installed in conjunction with a heat exchanger and a part of a hydronic system loop.

Typically, these products are installed as part of an integrated system to balance flow into both sides of a double-wall heat exchanger — one side increases the cold water supply temperature to supply domestic hot water, and the other side receives hydronic hot water that is cooled to supply the hydronic loop. The device controls the flow of water of both the cold water supply and the hydronic loop based on the temperature and flow requirements of the hydronic loop. This helps minimize dead legs in the hot water distribution system to supply fittings.

“LEC 2010 seeks to import the requirements surrounding proportional flow control devices, commonly found in European hydronic systems, and add the appropriate U.S. and Canadian code needs,” said Christopher White, ASSE Manager of Product Certification and Standards. “The LEC adapts translated requirements from DVGW VP 201, Testing Specification for Flow-rate Control Devices with Double Diaphragm and Safety Valve, and ASSE 1012, Performance Requirements for Backflow Preventers with an Intermediate Atmospheric Vent, for low hazard backflow protection.”

To purchase ASSE LEC 2010-2020, please visit the ASSE International Webstore at www.assewebstore.com. For questions regarding the LEC, contact White at chris.white@asse-plumbing.org.

ASSE International is an ANSI-accredited standards developer and product certification body composed of members representing all disciplines of the plumbing and mechanical industries.
ASSE’s product performance standards, professional qualifications standards, professional certification and product listing programs aim to improve the performance and safety of plumbing and mechanical systems. Learn more about ASSE International at

Last modified: December 19, 2023