Improper setting of air supply gear, excessive dust accumulation on filter screen, excessive dust accumulation on coil fins, low voltage and fan reversal.
Manifestation: the fan rotates but the air volume is small or no air is emitted

Poor lubrication or damage of fan bearings, excessive dust accumulation or damage of fan blades, friction between fan impeller and casing, soft connection between air outlet and external air duct or air supply outlet, soft connection between coil and drip tray and return pipe and drain pipe, operation of fan coil at high speed, loose fittings for fixing fan, loose louvers of air supply outlet.
Manifestations: excessive vibration and noise.

In the hydraulic strength test and leak test of pipeline system, only the pressure value and water level change are observed, and the leakage inspection is not enough.
Manifestation: leakage occurs after the pipeline system runs, which affects the normal use.

Improper setting of temperature gear, air in coil, abnormal water supply temperature, insufficient water supply, oxidation of coil fins.
Manifestation: the blown wind is not cold (hot) enough

Condensate pipes are concealed without water closing test
Manifestation: It may cause water leakage and loss to users.

The fan coil selection system was not washed carefully before completion, and the flow rate and speed could not meet the pipeline flushing requirements. Even water pressure strength test drainage is used instead of flushing
Manifestation: the water quality can not meet the operation requirements of the pipeline system, which often leads to the reduction or blockage of the pipeline section.

Hydrostatic test under negative temperature in winter construction
Manifestation: due to the quick freezing in the pipe during the hydrostatic test, the pipe is frozen.

After testing the water in the pipeline in cold areas, the accumulated water in the pipeline was not discharged in time in winter
Manifestation: pipes and parts are damaged by freezing, which causes water stoppage and repair, and affects normal production and domestic water consumption.

Rooms of the same type with the same pipes will not be used as model rooms.
Manifestations: The pipes in the room are the same but the practices are different, and the sizes of the throats are not uniform, resulting in rework.

The flange and gasket of pipeline connection are not strong enough, and the connecting bolts are short or thin in diameter. Rubber pad is used for heat pipe, asbestos pad is used for cold water pipe, double-layer pad or inclined pad is used, and flange pad protrudes into the pipe
Manifestation: the flange joint is not tight, even damaged, and leakage occurs. The flange gasket protrudes into the pipe, which will increase the flow resistance.