Maintenance and management methods of central air conditioning

Today, the editor of introduces to you several problems in the installation and maintenance of central air conditioning in the office, and proposes the following specific solutions, hoping to help you.

   1. Excessive noise from air conditioner terminal equipment and handling

   The running noise of the air-conditioning terminal equipment exceeds the standard, which is the most frequently encountered equipment sound problem in practice. Due to the relatively mature technology and other aspects of fan coil units, the products of many domestic manufacturers can meet the standards. However, the situation of large wind turbines is not satisfactory, and the measured values ​​of noise are often much higher than the product sample parameters provided by the manufacturer. The author has come into contact with two projects where the operating noise of the terminal equipment exceeds the standard: one is that the entrance and exit of the ceiling cabinet are equipped with mufflers, but the sound of the equipment itself exceeds the standard and comes out from the return air outlet; another example is There is no muffler at the entrance and exit of the ceiling-mounted cabinet. As a result, the measured value of indoor noise during the trial operation far exceeds the relevant indoor sound addiction standards. In the end, the two workers use frequency converters to reduce the fan speed to reduce the noise, but the cooling effect of the air conditioner is also greatly affected.

   Therefore, the noisy parameter requirements of the equipment should be marked in the design, and noise reduction and sound insulation measures should be considered when designing large air volume units. Carry out the unpacking inspection of the equipment in time when the equipment enters the site. It is best to conduct a power-on trial operation before the installation of the large air volume unit. If the voice exceeds the standard, you can promptly replace, return or modify the noise reduction measures to avoid entering the engineering commissioning after installation. It was discovered that the aircrew had problems with sound addiction, which caused major rectification.

   2. The circulation problem and solution of air conditioning water system

  The water system is the most important and the most critical part of the central air-conditioning project. Problems will directly affect the normal operation of the system. Central air-conditioning chilled water system alleviates common problems. The chilled water system has poor pipeline circulation. The first reason for the poor pipeline circulation is that the pipeline is not coordinated and handled properly during the construction due to the crossover of various professional pipelines, which causes many air bags in the pipeline network, which affects the pipeline network circulation. Second, the inadequate cleaning of the air-conditioning water system pipes directly caused the circulation of the air-conditioning water system to be blocked.

Based on years of practice, the author believes that for the first problem, the solution is to strengthen pre-construction management, rationally arrange pipeline elevations, try to avoid the occurrence of airbags, and at the same time set exhaust valves at the unavoidable airbags, and remove the Connect the exhaust pipe to a safe place to facilitate system exhaust. For the second problem, we should do a good job in several aspects during the construction process: First, the welded steel pipe must be mechanically or manually removed from dirt and rust before installation. When the inner and outer walls of the pipe are cleaned, the nozzle should be closed for installation. During the pipeline construction process, the unclosed pipe openings should be temporarily blocked to prevent dirt from entering, and the welding slag and hemp wire should be cleaned up in time when the pipe is connected. Second, the pipe network item is equipped with an automatic or manual exhaust valve, and a relatively large sewage valve is installed at the lowest point of the pipe network. If the blowdown valve is too small, the blowdown effect is poor, and the cleaning times are many. If it is not at the lowest point, the blowdown will be incomplete. Finally, temporary filters and bypass flushing valves should be appropriately added during the installation of the pipe network. Before connecting the equipment, perform segmented cleaning in conjunction with the water pressure test to prevent dirt from blocking the equipment. After the cleaning work is completed, a trial run of the water system cycle is required. The purpose is to flush and concentrate the dirt in the pipe network to the filter, and then remove the dirt from the filter.

   3. Dripping water formation caused by improper installation and its treatment

   There are many reasons for the problem of dripping and sleeping during commissioning and operation of the air-conditioning system. In summary, there are two major reasons: pipe installation and insulation. The connection between pipelines and fittings, pipelines and equipment is not tight, and the main reasons for water leakage are: pipeline installation does not strictly comply with the operating regulations. The quality of the pipe fittings was inferior, and the materials were not inspected carefully when they entered the site. The system did not conduct hydraulic pressure test strictly according to specifications.

  Common problems due to improper installation of the condensate pipe include:

   (1) The condensate pipe is too long, it is difficult to guarantee the ceiling during installation, or the slope is difficult to guarantee, or even the condensate pipe falls down, causing dripping: the condensate pipe of the air conditioning unit is not equipped with a water seal and the condensate of the unit cannot be removed.

(2) The solution to the installation problem during the construction of the above condensate pipe is to discharge the condensate as close as possible to avoid the phenomenon of the condensate pipe falling down and accumulating water or fighting with the ceiling; the condensate pipe of the cabinet should be set according to the negative pressure in the machine. Water seal to make the condensate drain unblocked.

  The main causes of heat preservation are: insufficient bulk density of the heat preservation material or uneven thickness of the heat preservation material. As a result, the outer surface temperature of the heat preservation material reaches the dew point temperature during operation and condensation occurs. The insulation material is not closely integrated with the outer wall of the pipeline. The end of the air-conditioning water pipe is not closed, which causes the moisture and heat insulation layer to cause condensation and dripping. The main reason for the dripping of the freezing pipe at the wall is that the insulation is not tight or the moisture-proof layer of the insulation material is damaged. The drain port of the wind grid coil drip tray was blocked by insulation materials and other sundries, and the condensate pipe was not cleaned up in time after installation and the condensate pipe irrigation and drainage tests were not performed. The insulation material of the drip tray of the ceiling cabinet and the fan coil is damaged, causing condensation on the drip tray.

   In view of these problems, the main solutions are: First, strengthen the inspection of the entry of insulation materials. It is necessary to strengthen the technical disclosure before construction and the inspection during the construction.

  Insulation sleeves cover small pipes to strengthen the quality control of the insulation quality of elbows, valves, flanges and equipment interfaces to ensure that the insulation layer is closely integrated with the outer wall of the pipeline. The third is to add insulation protection sleeves to the freezing pipes at the wall-piercing parts to strengthen inspections to ensure the continuity and tightness of the insulation layer at the wall-piercing parts. The fourth is to strengthen the cleaning and inspection of debris on the fan coil drip tray before the ceiling sealing plate. The fifth is to strengthen the protection of the equipment drip tray, especially the inspection before the ceiling sealing plate.

   Fourth, the selection and treatment of fire and smoke dampers

   Once a fire occurs in an office, it will often cause serious casualties and economic losses. In order to minimize the losses caused by the fire, effective fire prevention and smoke exhaust measures must be taken to control the spread of fire. Fire and smoke exhaust air valves play an important role in the rational design of ventilation, air conditioning and smoke prevention and exhaust systems. The fire damper is installed on the air supply and return pipes of the ventilation and air-conditioning system. It is usually open. When the temperature of the gas in the pipeline reaches 70~C during a fire, it will automatically close. It can meet the fire stability and complete fire resistance within a certain period of time. The valve is installed on the pipe of the smoke exhaust system. It is usually closed and automatically opens in the event of a fire. When the gas temperature in the pipe reaches 280qC, it automatically closes. Within a certain period of time It is a valve that can meet the requirements of fire resistance stability and fire integrity, and play a role in preventing smoke and fire. Many models of fire and smoke exhaust dampers are mainly evolved from the above two categories.

  There are often some problems in the management of air-conditioning project implementation. , Some problems are still very difficult. This requires us to do a good job of quality control carefully. Before the air-conditioning project is constructed, we must understand the design intent, be good at grasping the control points of the project, and manage the control points before, during, and after the event. The construction is purposeful and targeted. Carry out, point control, this will help us to do better engineering quality management.