Fan coil units
Controls expose savings potential for fan coil units
Mike Holding has some insight into the significant savings benefits of reconfigurable and cost-effective controls for fan coil units with reference to Dunham Bush’s recently launched Zone Flow – a fully integrated method of controlling fan coil units which will form part of a building’s overall control strategy
control a single fan within a unit, a complete multi fan unit, or operate as part of an integrated building management system (BMS). Whereas older sys- tems had separate control pack- ages, the Zone Flow provides a fully integrated unit mounted con- trol system. Zone Flow addresses two main concerns for customers and end users: it is innovative and reconfigurable so it gives much greater and more effective temper- ature control, and it is a particular- ly cost-effective arrangement offering savings of up to 25 per cent when compared with more traditional arrangements offering similar functionality.
Intelligent controls
Zone Flow has been designed to have BACnet based software but works with most, if not all, other BMS’s including LON and Modbus protocols. The intelligent con- troller is configurable for each individual client but utilises estab- lished stable and robust compo- nents and software and it is designed to communicate with other systems within a building utilising established protocols. The default programme covers most eventualities, but can be config- ured to communicate with most industry standard systems. As well as simplifying set up and maintenance, Zone Flow provides an ideal platform to opti- mise the operation of FCUs before they arrive on site, as we confirm and set the speed control and air volume of individual EC fan motors before a unit leaves the Dunham-Bush factory. Completed units are clearly marked to ease identification at site, and each will have been set to deliver correct output according to the selection and installation for the location in which it is to be installed.
Installation and monitoring Zone Flow can be used to control individual fans within a unit, a complete multi fan unit or multiple
units through a room mounted module. The operating schedule, temperature set points, and fan speeds can be reset in engineering mode with various levels of author- ity provided to suit the building operators’ requirements. A network of control specialists with knowl- edge of the controllers which form the basis of Zone Flow already exists across not only the UK but in many other regions as well. The controls for each FCU can be pre-set to take into account site conditions, ensuring that when the units arrive at site, they will deliv- er the correct air volume flow rate and will compensate for variations in system pressure, automatically. Zone Flow provides compre- hensive operating data and remote monitoring of all units, fan failure, alarms for filter dirty and conden- sate pump failure.
The communication with a BMS allows remote monitoring and adjustment of temperature set points and air volumes, as well as the monitoring alarm status. Where constant volume fans with EC motors are used, Zone Flow ensures design air flow is deliv- ered without adjustment of the unit. Zone Flow provides compre-
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The diagram illustrates the operation of Dunham-Bush’s Zone Flow method of control
hensive operating data and remote monitoring of units.
All communication is initially via BACnet using an RS 485 inter- face, but network communication can be by almost any protocol used by a BMS.
Cost effective solution
The new Zone Flow control units integrate with, and monitor fan coil units, saving on cost; and again are reconfigurable to any building management system. The Zone Flow fan coil unit controls can be specified with many of Dunham-Bush’s industry-leading fan coil units, simplifying commis- sioning, set up, adjustment and maintenance of the FCUs, and will integrate with the requirements of most building control strategies. The complete Zone Flow package is pre-tested, and our engineers ensure that Zone Flow equipped fan coil units are already set up ready to work and verified as part of the commissioning package, saving time and increas- ing efficiency, as well as providing significant savings at initial installation and throughout the life of the product, when compared to more traditional arrangements.
PICVs
In addition to delivering fixed air volume flow rates, temperature control and scheduling, Zone Flow can also control pressure independent control valves (PICVs) – a technology which is accepted as a proven application for optimising hydronic system delta T, enhancing system per- formance and reducing energy cost. A high quality PICV offers precise hydronic flow control for heating and cooling applications for use in the HVAC (heating, ven- tilation and air conditioning) industry and offers five major operational features: accurate flow control; wide range of operation; no need for system balancing due to pressure independent opera- tion; enhanced system delta T per- formance which results in optimis- ing overall system efficiency; and enhanced system control. This simplifies and reduces the cost of commissioning, while ensuring optimum performance in terms of comfort and energy con- sumption. All Dunham-Bush Fan Coil Units are manufactured at Havant and are available with high efficiency EC motors providing infi- nitely variable fan speed control. The new product provides time scheduling, the control of standard or pressure independent water control valves, fan speed control, electric heating where required, as well as the management of the Zero Energy band. Dunham-Bush offers a compre- hensive range of high specifica- tion fan coil units, from the Panther at 280mm deep, the Leopard at 230mm deep and the Cougar at 180 mm deep which has single entry bottom access fans. External Rotor EC fan/motor assemblies are fitted as standard to these units, and other variants such as vertical and cased units are also available.
// The author is the managing director of the fan coil unit specialist Dunham-Bush Limited //
HVR | July 2014 | 31
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