COOLING
Variable water flow system ( VWF )
Variable water flow is a hydronic control function package that permits control of the water flow rate .
The 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 hydronic module includes pressure transducers that permit intelligent measurement of the water flow rate and real-time display on the Touch Pilot Junior interface . All adjustments can be made directly on the interface , speeding up start-up and maintenance .
As 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
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Full-load set point The flow rate control at full load uses the Touch Pilot Junior 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 Touch Pilot Junior includes two part-load operating modes : --
Constant outlet pressure control
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Constant delta T control .
Features and advantages
Quiet operation
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Compressors --
Low-noise scroll compressors with low vibration level
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The compressor assembly is installed on an independent chassis and supported by anti-vibration mountings
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Dynamic suction and discharge piping support , minimising vibration transmission ( Carrier patent )
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Condenser ( 30RBSY ) section --
Vertical condenser coils
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Protection grilles on anti-vibration mountings to protect the heat exchanger against possible shocks ( 30RBSY 090-160 ( optional )).
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Low-noise latest-generation Flying Bird IV fans , made of a composite material ( Carrier patent ) are now even quieter and do not generate intrusive low-frequency noise
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Fan motor controlled by a variable-frequency controller , to allow adjustment of the fan speed in accordance with the ducting for optimised efficiency .
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Rigid fan installation for reduced start-up noise ( Carrier patent )
1 – Constant unit outlet pressure control
The control continuously acts on the pump speed to ensure a constant outlet pressure .
This solution is suitable for installations with two-way valves . When these close , the water speed will accelerate in the system branches that are still open . For a fixed-speed pump this results in an unnecessary increase of the pressure at the pump outlet .
The outlet pressure control mode ensures that each circuit branch always has a uniform supply , without unnecessary energy waste .
In industrial processes such as plastic injection moulding , this solution ensures that each terminal unit has the correct pressure supply .
2 – Constant delta T control
The VWF algorithm maintains a constant delta T no matter what the unit load , reducing the flow rate to the minimum .
This solution can be used for systems with two-way or threeway valves and achieves higher energy savings than the “ Constant unit outlet pressure control ” mode . It is suitable for the majority of comfort applications .
Easy and fast installation
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Physical features --
Flying Bird IV fans controlled by a variable-frequency controller to provide up to 240 Pa available pressure ( depending on the size ) at nominal flow rate
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Flow control in accordance with the ducting for optimised efficiency with the possibility to program a maximum supply air flow .
-- Supply air duct connection frame .
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Suction air connection frame standard for sizes 30RBSY 039-080
-- Suction air filters optional ( 30RBSY 039-080 )
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Small unit footprint with a low height ( 1371 mm ) for easy installation in most buildings
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The unit is enclosed by easily removable panels , covering all components ( except air heat exchanger and fans ).
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Integrated hydronic module ( option ) --
Centrifugal low or high-pressure water pump ( as required ), based on the pressure loss of the hydronic installation .
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