Central air conditioning fresh air unit maintenance and common problems

The fresh air system refers to the air pipe system that is fed into the room after the air is filtered and humidified by the fresh air unit. The fresh air system regulates and controls the fresh air volume in the room, meets the normal needs of people, and avoids air conditioning diseases and boredom caused by insufficient fresh air volume.

The fresh air unit is composed of a filter, a surface cooler, a heater, a humidifier and a fan, which has a simple structure and a high possibility of failure. The fresh air unit may be used for temporary heating in the construction stage before it is officially put into operation, and it is a kind of heat exchange equipment that is easy to freeze and crack. When the outdoor temperature is low, any link in the pressure test and water filling, pipeline flushing and operation are prone to freeze and crack failures.

Insufficient attention to the safe operation of the fresh air unit often causes the freezing crack of the heat exchanger, which not only brings economic losses to the air conditioning system itself, but also indirect economic losses caused by the freezing crack of the heat exchanger are often not small, because the freezing crack accident of the heat exchanger is often found late, and the running water everywhere often endangers the nearby elevator, cable well and the floor below. If attention is paid to the safe operation of the fresh air unit in the various stages of construction, commissioning and operation, the freezing cracking accident of the heat exchanger can be basically avoided.

Process of use and inspection of fresh air units

First, check the items before and after starting

1. Check whether the drive belt of the fan is relaxed.

2. Check whether the bearing of the fan and motor is normal.

3. Check whether the condensate coil is clean and whether there is foreign matter at the water outlet of the water receiving pan.

4, check whether the heater is normal, measure the voltage and resistance.

5, check the machine for other abnormal conditions.

6. Check the seal and leakage of the filter

7. Check whether the inlet and supply air valves are open

2. Daily inspection and maintenance

1, the filter in the air conditioning unit is cleaned once a month.

2. Pay attention to the working current of the daily fresh air unit

3, pay attention to the pressure difference before and after the filter, if the pressure difference is too large to clean in time.

4, pay attention to belt wear, if the belt wear is serious timely replacement.

Third, fresh air unit safety recommendations

1, winter operation should pay attention to the anti-freezing of all air conditioning equipment and pipelines. Outdoor temperature should be paid attention to when pipeline pressure test flushing, and the system must be completely emptied after flushing. Temporary heating with fresh air units should also be tested according to normal procedures, if there is no self-control measures and special management, it is recommended not to use fresh air conditioning equipment for temporary heating.

2. Establish and improve the operation management system. At night, the fresh air unit should also use a fixed water flow rate or temperature controller to automatically control the opening of the water valve or set an electric heating device to ensure the temperature of the heater of the fresh air unit. The fresh air unit should be regularly inspected during winter operation to track weather changes, and it is not appropriate to arrange the commissioning and maintenance of the air conditioning system in cold weather to ensure the safety of the operation of the air conditioning water system.

3, the design of the fresh air unit must be set up effective anti-freeze automatic control interlock monitoring device. When the fan is running, the rated water flow of the heater must be ensured first. When the water temperature is too low or the water flow is too small, the alarm function should be provided and the fan and fresh air inlet insulation air valve should be closed in time.