Variable Water Flow system (VWF)
Carrier Variable Water Flow
COOLING
Recommended by Carrier, the AquaSnap can be equipped
with one or two variable-speed pumps to save significant
pumping energy cost (more than two-thirds), ensure tighter
water flow control, and improved overall system reliability.
Carrier Variable Water Flow (VWF) is a hydronic control
function package that permits control of the water flow rate.
The Carrier VWF not only ensures control at full load, a
specific Carrier algorithm linked to an electronic frequency
converter also continuously modulates the flow rate to
minimise pump consumption at full load as well as part load.
The Carrier hydronic module includes pressure transducers
that permit intelligent measurement of the water flow rate
and real-time display on the Pro-Dialog+ or Touch Pilot
user interface. All adjustments can be made directly on the
interface, speeding up start-up and maintenance.
As Carrier VWF acts directly on the pump, the system no
longer requires the control valve at the unit outlet. However,
for applications with two-way valves a bypass system must
be kept to guarantee the minimum flow rate.
Operating logic
■■ Full-load set point
The flow rate control at full load uses the Pro-Dialog+ or
Touch Pilot user interface, reducing the pump speed. This
first control saves energy that would normally be dissipated
in the control valve. For example, if the pressure supplied by
the pump is reduced by 20% the power consumption of the
pump is reduced by the same ratio, compared to a traditional
installation.
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■■ Operating mode at part load
Pro-Dialog+ includes three part-load operating modes:
-- Fixed speed control
-- Constant delta P control
-- Consta