About Chilled Water Air Conditioning Systems
Controlling temperature, humidity, air movement and air cleanliness, and heat radiation normally with mechanical means, to achieve human thermal comfort, is what Air conditioning means to people.
The means by which the controllable cooling is accomplished in the conditioned space can be categorized for Air conditioning systems. Specific purposes by special equipment arrangement are what they are further segregated to accomplish. The UK has a host of companies, specializing in supply, design and installation of air conditioning systems.
In selecting a suitable air conditioning system for a particular application, a few things should be taken into consideration. Firstly, the System Constraints which include cooling load, zoning requirements, heating and ventilation. Next are Architectural Constraints like size and appearance of terminal devices, acceptable noise level, space available to mount the equipment and its location relative to the conditioned space, and acceptability of components obtruding into the conditioned space. Lastly is the Financial Constraints, which cover capital cost, operating costs, and maintenance cost.
All Air Systems, Air and Water Systems, All Water Systems including cooling towers which can also be applied to the first two systems mentioned, and Direct Expansion Systems – are the four basic system categories for Air Conditioning Systems.
Central chilled water air conditioning systems which are all-air systems are one of these. They provide complete sensible and latent cooling capacity in the cold air supplied by the system. Be it the central system or at a particular zone – the same air stream can accomplish heating for both. Classification into Single duct systems and Dual duct systems is possible for all-air systems.
System Advantages:
* The central plant is located in unoccupied areas, hence facilitating operating and maintenance, noise control and choice of suitable equipment.
* No piping, electrical wiring and filters are located inside the conditioned space.
* Use of greatest numbers of potential cooling situations with outside air in place of mechanical refrigeration is allowed.
* Readily adaptable to climatic control and simple – the seasonal changeover is both.
* A wide choice of zone ability, flexibility, and humidity control under all operating conditions is given.
* Readily available incorporation of Heat recovery system exists.
* Good design flexibility for optimum air distribution, draft control and local requirements is allowed.
* Well suited to applications requiring unusual exhaust makeup.
* Infringes least on perimeter floor space
* Adaption to winter humidification
System disadvantages:
* Unusual floor space can be reduced by additional duct clearance which is required.
* Difficulty exists for air-balancing and great care is required.
* Close cooperation between architectural, mechanical and structural engineers is what accessibility to terminals demands.
Distribution Components
A number of important components exist for Distribution systems.
The Air Handling Unit is a cabinet that includes or houses the central furnace, air conditioner, or heat pump and the plenum and blower assembly that forces air through the ductwork.
Air from the air handler to the rooms in a house is carried by the Supply Ductwork. Each room usually has at least a supply duct and larger rooms generally have several.
From the conditioned space the Return Ductwork carries air back to the air handler. Most houses have only one or two main return ducts located in a central area.
Supply and Return Plenums are boxes made of duct board, metal, drywall or wood that distribute air to individual ducts or registers.
A branching network of round or rectangular tubes generally constructed of sheet metal, fiberglass board, or a flexible plastic and wire composite material located within the walls, floors, and ceilings is what the Ductwork is. Metal, fiberglass duct board, and flex-duct are the three most common types of duct material used in home construction.
Installed between the register and plenum box, or plenum box and air handler, usually in a single, continuous piece is the Flex-duct. While flex-duct has fewer seams, the inner lining and outer insulated covering can tear or be pinched closed. Also longer flex-duct runs can restrict the flow of air; proper design and installation is very important.
Rigid and installed in pieces are what both metal and fiberglass duct board are. An insulation material, like flex-duct, is what the Fiberglass duct board made of. Sections of the duct board is what the Ducts are made of. Carefully sealed with mastic or high quality duct tape, is what seams in the duct board should be.
Rectangular Metal Duct, especially the kind used for plenums and larger trunk runs, is often insulated on the inside with fiberglass duct liner. If it is not insulated on the inside, metal ducts should be insulated on the outside using a fiberglass battery with an attached metal foil vapor retarder. At least two inches thick, is what the insulation should be with the vapor barrier installed on the outside of the insulation facing away from the duct.
Stapled together around the duct and then taped – is what usually happens to seams in the insulation. All of the seams should be sealed before insulation is installed. All return and supply ducts located outside the conditioned space, in attics, crawlspaces, or basements, for example, should be sealed and insulated.
Ductwork Joints, which join pieces of ductwork, are the other important components. Joining the pieces of ductwork, the Ductwork Joints are included as other important components. There are also the Elbows, which are manufactured pieces of duct used for turns. Boots that connect ductwork to registers also exist. Lastly, covering the duct openings into the conditioned space are the Registers and Grilles.
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