My colleague Terry Burger has written about the efforts to include ASSE’s two newest standards, ASSE 1103, Performance Requirements for Pilot Operated Water Pressure Reducing Valves for Potable Water, and ASSE 1379-2024, Proportional Flow Control Devices, with Protection from Cross-Connection via Hydronic Water, for use in Potable Water Installations, into the plumbing codes (see his article “ASSE 1103, ASSE 1379 and Codes.”). I wrote about ASSE 1103 in the July-September 2024 edition of Working Pressure, so this article will focus on ASSE 1379.
ASSE 1379 was developed to maximize the heating efficiencies of domestic hot water while controlling the flow of potable water, using proportional flow control devices. These devices control the flow of water based on the pressures of the hydronic water in a hydronic system. This is achieved by using an integral cross-connection protection between the potable and hydronic water, used in conjunction with a heat exchanger, as part of a hydronic loop system to provide domestic hot water locally. A 1379 device facilitates a constant ratio of flow between the potable and hydronic water streams entering the heat exchanger, which enables a stable hot potable water supply. As the ASSE 1379 scope states: This device consists of a single potable cold water supply inlet and outlet, and a single hydronic supply inlet and outlet, a means of dynamic flow control (piston), an atmospheric vent, and two sets of three dynamic seals between the potable and hydronic flow paths (see figure).
The performance requirements and compliance testing of this standard includes the following: a tightness test, hydrostatic testing of the device, suitability for use, life cycle testing, as well as a backsiphonage test and two different backflow tests. Some parameters of the standard are as follows:
- The maximum rated flow rate on the potable flow path shall be 0.57 L/sec (9.0 GPM).
- The maximum rated flow rate on the hydronic flow path shall be 0.57 L/sec (9.0 GPM).
- The maximum operating temperature for the device is 90°C (195°F).
- The maximum static pressure, on the potable and hydronic flow paths, is 1241 kPa (180 psi.)
The Tightness Test requires the potable and hydronic water side of the device to be pressure tight at 1600 kPa (232 psi) for 60 seconds. This is tested to ensure no contamination of the potable water supply. Likewise, the entire device must undergo a Hydrostatic Pressure Test at 2500 kPa (363 psi), or two times the manufacturer’s rated pressure, whichever is greater, which is applied for a period of 10 minutes.
The Suitability for Use testing requires devices to demonstrate their ability to maintain the appropriate flow rate with respect to the acceptable pressure loss as laid out in the standard. This section also ensures the seals of the device will not fail at elevated flow rates while operating with acceptable pressure losses as well as the applicability of the devices for its intended use.
In order to pass the Life Cycle Test, the device must demonstrate its ability to work without failure for a minimum of 10 years without damage. This is validated by cycling the device 182,500 times. The large number of cycles simulates 10 years of service (~50 cycles per day for 10 years).
The final three tests require the device to demonstrate its ability to avoid contamination of the potable water line. The backsiphonage test simulates the case where a vacuum is created on the potable water line of the device and the hydronic pressure is operating at atmospheric pressure and all seals have failed. The next test is used to verify that no backflow from the hydronic piping into the potable water supply occurs when one set of seals fails. The final backflow test verifies that no backflow into the potable water supply will occur when the vent port outlet is sealed closed then the maximum rated working pressure is applied to the hydronic piping side of the device.
Employing an ASSE 1379 device can result in significant energy costs savings due to eliminating the standby losses of a centralized domestic water system. Additionally, an ASSE 1379 device allows for a reduction in the amount of domestic hot water (DHW) and the number of DHW recirculation lines needed in buildings. Beyond the energy savings, designers will realize savings as a result of fewer pipe supports needed, fire penetrations, insulation and accessories required for the overall design of building projects.
If you have an ASSE 1379 device that you would like certified, please contact staffengineer@asse-plumbing.org.
