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HVAC (Heating, Ventilation and Air Conditioning) equipment needs a control system to regulate the operation of a heating and/or air conditioning system. [1] Usually a sensing device is used to compare the actual state (e.g. temperature) with a target state. Then the control system draws a conclusion what action has to be taken (e.g. start the ...
These motors are sometimes called DC motors, sometimes EC motors and occasionally DC/EC motors. DC stands for direct current and EC stands for electronically commutated.. DC motors allow the speed of the fans within a fan coil unit to be controlled by means of a 0-10 Volt input control signal to the motor/s, the transformers and speed switches associated with AC fan coils are not required.
These sense the air temperature using the differential expansion of two metals to actuate an on/off switch. [14] Typically the central system would be switched on when the temperature drops below the setpoint on the thermostat, and switched off when it rises above, with a few degrees of hysteresis to prevent excessive switching.
An air conditioning system, or a standalone air conditioner, provides cooling and/or humidity control for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against the system intended to maintain constant indoor air conditions.
This is partly because ice forms on the outdoor unit's heat exchanger coil, which blocks air flow over the coil. To compensate for this, the heat pump system must temporarily switch back into the regular air conditioning mode to switch the outdoor evaporator coil back to the condenser coil, to heat up and defrost. Therefore, some heat pump ...
The study of the behavior of air-water vapor mixtures. Water vapor plays an important role in energy transfer and human comfort in HVAC design. rooftop unit (RTU) A packaged unit that controls both heating and air conditioning. An air handler typically refers to a unit that provides a fan to support either heating or cooling. radiant ceiling panels
Reversing valves are built into the heat pump by the manufacturer, and must be replaced by an HVAC technician if they fail. Since the valve is an integral part of the sealed refrigerant circuit, proper procedures for recovering and then later refilling the refrigerant must be followed, to prevent its loss into the atmosphere.
Some air conditioning equipment manufacturers install crankcase heaters either in the compressor (insertion type), or mount them externally around the base of the compressor (bellyband type). The two wires of the heater are wired directly to the input side of the contact from the main power supply, and power is always supplied to the heater.