HVAC Controls
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Actuated Valves
Head Office
®
Neptronic
400 Lebeau Blvd.
Montreal, Quebec, Canada H4N 1R6
Tel.: (514) 333-1433
Fax: (514) 333-3163
Toll Free: 1-800-361-2308
Under Pressure
Pressure Independent Control Valves (PICV): Principle of Operation
Pressure Independent Control Valves (PICV) can help reduce energy costs and increase
occupant comfort in heating and cooling coil applications in buildings. A PICV is best described
as two valves in one: a standard 2-way control valve and a balancing valve.
PICV obtain optimal results because only the necessary amount of hot water (in GPM) and
chilled water (in GPM) is delivered to the heating and cooling coils. Standard 2-way control
valves allow for overflow and underflow especially if the CV is oversized or undersized. This
generates excess water to the pump to compensate for their inaccuracy, which increases
pumping cost.
The actuators on PICV valves do not cycle as often as standard 2-way valves to compensate for
pressure changes in the system that impact the flow, which results in energy savings.
Here is a simplified explanation of PICV operation using a two-valve system. The second valve
(V2 in the graphic below) regulates the pressure differential across the first valve (V1) using a
rolling diaphragm element counter-acted by a spring. The first valve is a calibrated variable
orifice device adjusted by the actuator (similar to a standard modulating control valve).
The diaphragm reacts to the system and regulates the pressure differential across the actuated
control valve orifice to maintain its flow rate.
USA
NEP Inc.
P.O. Box 1151
Medford Oregon,
USA 97501
Tel.: (541) 531-5746
Middle East & Asia
NEP International FZE
P.O. Box 125687,
Dubai, UAE
Tel.: +97155 8825487
Fax: +9714 3426772
Singapore
Neptronic Pte Ltd
Office D6, #03-38,
Mountbatten Square
229, Mountbatten Road,
Singapore – 398 007
Mobile: +65 8118 4184
Tel: +65 6650 6212
Fax: +65 6491 6423
On a PICV (see graphic below), when pre-setting the maximum flow rate, the inlet orifice
changes in size, which does not interfere with the length of the stroke. When modulating, the
orifice areas are affected by the actuator using the full stroke. This results in the orifice area
changing in size with a vertical movement.
HVAC Controls
Electric Actuators
Actuated Valves
Humidifiers
Electric Heaters