Designing and commissioning variable flow hydronic systems

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · ASHRAE Journal (American Society of Heating, Refrigerating and Air-Conditioning Engineers); (United States)

OSTI ID:6012999

Avery, G ^[1]

---

1. Kele and Associates, Memphis, TN (United States)

Direct return variable flow hydronic systems (VFHS) must (in this author's opinion) be designed to be self-balancing. However, in practice, many design engineers will use customary pipe sizing routines, piping detail drawings and specifications that apply to more familiar constant flow systems. Substituting a two-way valve in place of a three-way valve and bypass pipe, while retaining the balancing valve and balancing specification, ultimately creates control problems and wastes energy. The use of balancing valves on VFHS is detrimental to the system's performance because it reduces the authority of the control valve and adds a permanent restriction in every branch. This restriction increases the pumping costs for the life of the building. Specifications for VFHS must stress the importance of the valve actuator and the need for high quality valve bodies to withstand the additional dynamic forces and static pressures that are present in these systems. The working pressures for VFHS are always higher than for equivalent constant flow hydronic systems (CFHS). On many VFHS, the use of conventional HVAC control valves may not be suitable. This article addresses these problems and the important role the balancing contractor has in testing and commissioning these systems.

• OSTI ID: 6012999
• Journal Information: ASHRAE Journal (American Society of Heating, Refrigerating and Air-Conditioning Engineers); (United States), Journal Name: ASHRAE Journal (American Society of Heating, Refrigerating and Air-Conditioning Engineers); (United States) Vol. 35:7; ISSN 0001-2491; ISSN ASHRAA
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320106* -- Energy Conservation
Consumption
& Utilization-- Building Equipment-- (1987-)
CONTROL EQUIPMENT
DESIGN
ENERGY SYSTEMS
EQUIPMENT
FIELD TESTS
FLOW REGULATORS
PERFORMANCE TESTING
PIPES
SPACE HVAC SYSTEMS
TESTING
VALVES