Siemens Building Technologies (Controls) - Control Valves in HVAC Applications
Control Valves - HVAC Applications - Kvs - Sizing Chart - Variable Flow
General Guidance for the Use of Control Valves in HVAC Applications
This information is intended as a general guide for the application of HVAC control valves. Please consult the manufacturers relevant data sheets for detailed specifications.
- Control valves must be suitable for the medium and operating pressure
- Modulating type control valves must not be used where tight shutoff is required
- Control valves can be manufactured with +/- 10% tolerance on the Kvs value. They should not be used as a reference for balancing purposes
- “Mixing valves” have 2 inlets and 1 outlet
- “Diverting valves” have 1 inlet and 2 outlets
- Most manufacturers' valves are “mixing valves” and when used in a diverting application must be placed in the return
- Most valves will work when installed in any position (see relevant manufacturers' details), however they should be installed upright as far as possible
- Installing valves upside down should be avoided as any water leakage will run into the electrical actuator and may result in damage
- Valves should be installed with sufficient room available for removing the actuator and complete valves for inspection purposes.
- Isolating valves and quick disconnect fittings should be installed to ease removal
- Water systems should be cleaned, flushed and treated in accordance with current good practice, as described, for example in the BSRIA Applications Guide AG 8/91 and AG 2/93
- For further relevant information, see CIBSE Guide B (Section 7)
(For Valve Sizing Chart and Typical Mixing Valve Applications see diagrams right).
Hints on Sizing Control Valves
The valve sizing chart is based on the Siemens Building Technologies magnetic valve, Kvs/size may vary for other types and manufacturers
Control valves should be sized relative to the pressure drop in the “variable flow part” of the circuit
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