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Q: What is a Fan Coil Unit (FCU)?
A: A fan coil unit is an indoor terminal device of a water-based central air conditioning system, consisting of a heat exchanger, fan, and filter. It provides cooling or heating by circulating chilled or hot water, while the fan delivers the treated air into the room. Since water is the medium, the airflow is gentle and temperature/humidity control is precise, making FCUs a popular choice for high-end hotels and residences.
Q: Is water-based central air conditioning widely used?
A: A: Very widely. All five-star hotels, hospitals, and large public buildings worldwide adopt water-based central air conditioning. Nowadays, more high-end residences and villas also choose it as their preferred solution, focusing on its outstanding comfort and stability.
Q: How effective is a water-based air conditioning system?
A: Widely adopted in five-star hotels, water-based central air conditioning is known for its soft airflow, uniform temperature distribution, absence of strong drafts, and low-noise operation—making it a standard for high-quality indoor comfort. However, its superior performance depends heavily on professional design and proper installation, especially on precise matching between outdoor main units and indoor terminals.
Q: Some people say this is a new product. Is the technology mature?
A: Water-based air conditioning is not new. It has been in use for over a century, and the technology is very mature. Terms like “air-source heat pump,” “air-cooled heat pump,” and “hydronic system with underfloor heating” all fall under the water system category, though names vary by application and historical context.
Q: Is a water-based central air conditioning system the same as the commonly seen refrigerant (VRF) system?
A: No. Central air conditioning has two major technical routes: water-based systems and refrigerant (VRF) systems. Water systems, originating in the U.S., emphasize comfort, can be connected to FCUs and underfloor heating, and provide stronger overall performance. VRF systems, originating in Japan, focus on cost efficiency and energy savings, are easier to install, but less comfortable compared to water systems.
Q: Why is a water-based system more comfortable?
A: The key lies in controllable water temperature and a small heat exchange temperature difference (only about 5°C). This results in gentle airflow, avoids excessive dehumidification, and prevents indoor dryness. By contrast, VRF systems operate with a much higher heat exchange temperature difference (40–70°C), which easily leads to excessive condensate and dry indoor environments, causing discomfort during prolonged use.
Q: VRF systems can also provide heating. Why still recommend water-based systems?
A: VRF systems are mainly designed for cooling, with heating as a supplementary function. Under low-temperature, high-load conditions, their performance is often unsatisfactory. Water systems, on the other hand, are designed for year-round use and can be combined with underfloor heating in winter, offering efficient, quiet, and evenly distributed heating—far superior to direct VRF heating.
Q: How should one choose a system?
A: For those pursuing maximum comfort, year-round mild heating and cooling, and with sufficient budget, the combination of water system + fan coil units + underfloor heating is the ideal choice. If the focus is more on initial investment and installation convenience, VRF systems remain the mainstream solution. It is recommended to decide after in-depth consultation with professional service providers.
