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The supply pipe supplies either cold or hot water to the unit depending on the time of year. Four-pipe fan coil units have two supply pipes and two return pipes. This allows either hot or cold water to enter the unit at any given time. Since it is often necessary to heat and cool different areas of a building at the same time, due to ...
A chiller boiler system is a hydronic system. It uses water instead of air to heat and cool a structure. A properly designed hydronic system is usually more efficient than a standard forced air system. [1] Chiller boiler systems use radiant heating and cooling or fan coil systems to condition a home or business. This allows for multiple zones ...
A chilled beam is a type of radiation/convection HVAC system designed to heat and cool large buildings through the use of water. [1] This method removes most of the zone sensible local heat gains and allows the flow rate of pre-conditioned air from the air handling unit to be reduced, lowering by 60% to 80% the ducted design airflow rate and the equipment capacity requirements.
A run-around coil installation, serving air handling units on the roof of an office building. A run-around coil is a type of energy recovery heat exchanger most often positioned within the supply and exhaust air streams of an air handling system, or in the exhaust gases of an industrial process, to recover the heat energy. Generally, it refers ...
Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented by Daikin Industries, Ltd. in 1982. [1] Similar to ductless mini-split systems, VRFs use refrigerant as the primary cooling and heating medium, and are usually less complex than conventional chiller-based systems.
By comparison, most modern "warm air" furnaces typically use a fan to circulate air to the rooms of house and pull cooler air back to the furnace for reheating; this is called forced-air heat. Because the fan easily overcomes the resistance of the ductwork, the arrangement of ducts can be far more flexible than the octopus of old. In American ...
For a human-powered version, see yakhchal.. When the ambient air temperature drops to a set temperature, a modulating valve allows all or part of the chilled water to by-pass an existing chiller and run through the free cooling system, which uses less power and uses the lower ambient air temperature to cool the water in the system.
In a design study of functionally equivalent 5 kW HVAC heat exchangers, tube materials in the coils weighed 3.09 kg for 9.52 mm diameter tube, 2.12 kg for 7 mm diameter tube, and 1.67 kg for 5 mm diameter tube. Tube weight was reduced by 31% when copper tube diameters were downsized from 3/8 inch to 7 mm. Tube weight was reduced by 46% when ...