The comfort of life to the environment is getting higher and higher, and more and more intelligent, in today's ever-changing society, air conditioning has become an indispensable part of people's living status, the use and installation have become things we often encounter, and the good operation of air conditioning equipment is inseparable from the installation process. To ensure the quality control of the construction process of the air conditioning installation project, standardize the operation of the quasi-side, inspection and testing, is an indispensable link, the early drawing review and pipeline drawing is the preferred way to avoid bad operation.
There will be many problems in the installation process of the purification air-conditioning system in the dust-free workshop, including the most main: first, the pipeline elevation, the problem of positioning crossing, the second design drawings are unreasonable, the inoperability of the air-conditioning installation, the third vibration and noise exceeds the standard, the fourth, the drainage is blocked or unsmooth, the problem of condensation dripping, the problem of water circulation of the fifth air-conditioner, etc., Hejing Smart Construction Company will explain in detail the relevant discussion of HVAC construction.
HVAC installation and construction problems and detailed responses
First, the pipeline elevation and positioning cross seriously
HVAC engineering is a very critical link in the building facilities, the pipelines involved are varied because of different uses, and relatively speaking, it is very complex, although in the early stage of construction, the accurate calculation of the cooling load of the construction area has also been formulated feasible engineering design drawings, but the detailed proofreading can not be carried out during the construction, it will cause the serious phenomenon of pipeline elevation and positioning crossing, and it has become the biggest obstacle in the actual construction process. Usually, in the case of construction according to the design drawings, the construction of the first installed pipeline is very convenient, and the later installation of HVAC becomes very difficult, which will affect the progress and quality of the installation.
Problem analysis and response:
Usually, the complete design drawings are drawn by the professionals of the design unit, including the ambiguity, fire protection, process pipelines, electrical, etc., but the construction unit must integrate the existing pipelines, conduct comprehensive consideration, reasonably control the elevation, and carry out pipeline distribution in line with the piping principle.
Such as: 1) Small tube makes big tube: small tube is easy to bend, and the cost is low and the space occupied is small, easy to change and move the installation.
2) Branch pipe let the main pipe: the branch pipe is generally smaller in diameter, and the cost is low, in addition, the influence range and importance of the branch pipe is not as good as the main pipe.
3) There is a pressure pipe to let the non-pressure pipe; The medium in the non-pressure pipe flows from high to low by gravity, and its main characteristics are slope requirements, pipeline impurities, and easy blockage, so the non-pressure pipeline should be kept in a straight line, meet the slope, and try to avoid too many turns to ensure smooth drainage and meet the height of the space. Generally speaking, changing the direction of the pipeline, cross arrangement, and detour will not affect its water supply effect, while the non-pressure pipeline will have a greater impact on the flow rate if it changes the slope and flow direction.
4) The construction is simple and the avoidance construction is difficult: this is considered from the aspect of avoiding increasing the difficulty of installation; If the amount of work is small, the amount of work will be large: this is considered from the aspect of avoiding increasing the amount of installation work. New pipelines avoid existing pipelines: this is considered from the aspects of reducing cost, engineering quantity and construction difficulty.
5) Electricity is on top, water is on the bottom: the liquid pipeline is installed in the vertical direction of the electrical equipment of the electrical box below to avoid secondary damage and equipment loss caused by pipe bursting or condensate due to pressure changes.
According to the piping principle, the reasonable configuration of the integrated pipe frame and pipeline can be considered. In this way, the pipelines can be arranged neatly, and the cost of the bracket can be saved; More importantly, rearranging and assigning each professional drawing can make the direction of the pipeline clearer and avoid cross-conflict in advance.
Second, the design drawings are unreasonable, and the air conditioning installation is not operable
In the early stage of construction, it is necessary to design reasonable and effective construction design drawings, in order to ensure the effectiveness of the construction drawings, the staff should carry out a simulation plan for the construction area, formulate the most reasonable engineering construction plan while solving the basic elements of the project, and only ensure the progress and quality of the project while ensuring the scientific rationality of the engineering drawings, and improve the speed and quality of HVAC in the installation and construction; But if the design is detached from the site and the construction is not executed, then the design is a failure.
Problem analysis and response:
After the construction simulation plan makes a preliminary plan for the pipe diameter, type, size of air conditioning equipment and maintenance space of the drawings, it is necessary to determine the piping direction, installation type, size and so on for pipeline installation and equipment procurement.
If it is found that the installation location of the air-conditioning equipment cannot meet the normal construction and maintenance space, or the pipeline elevation conflicts with the limited space of the ceiling, it is necessary to submit construction doubts or apply for design changes to the design unit, and list and summarize the problems one by one, so as to answer and solve the construction problems in a unified manner.
3. Excessive vibration and noise
This is the most common problem in HVAC design, such as the measurement of the noise index, the actual measured value is much higher than the sample parameters given, which requires that in the actual construction process, the noise index of the air conditioning equipment should be clarified, and the sound insulation treatment of the large air volume unit, during the construction, the large air volume air conditioning unit should be energized to test the noise index, once it does not meet the standard, it should be replaced in time to ensure that the sound insulation effect is good and then the construction is carried out to prevent future rework.
Problem analysis and response:
Noise reduction is still targeted, and noise generation is also divided into several types:
1) Mechanical friction sound of equipment operation: This can be eliminated through debugging and inspection, such as the contact between the fan impeller and the shell or the shock absorber fixing piece for equipment transportation is not removed, which can be corrected and adjusted.
2) Pipe noise caused by air duct wind speed, elbow and pipeline installation: First of all, the designed air duct installation occasion should be evaluated, and the wind speed of the air duct should be controlled at 5 10m s according to different functions, and the higher the noise requirements, the lower the wind speed should be; The second is the position of the elbow and the equipment interface, because it is connected with the equipment, the sound of the fan will be directly transmitted to the pipeline.
3) The equipment selection is not matched, and the pressure head is too large: this situation may be that the pressure loss along the original design pipeline is too large, but the actual pressure loss is small, and there may be a large difference between the rated air volume and the actual air volume, resulting in noise, which can still be corrected later; Through the air volume test of return air or air outlet, and compared with the original design air volume, the transmission ratio of the motor and the impeller can be adjusted, the pulley can be replaced, and the appropriate adjustment can be made, so the method can only be regarded as a remedial measure, and the range of adjustment is limited, so the control source or the early stage of design should be fully considered.
Fourth, the drainage is blocked or not smooth, and the problem of condensation and dripping
Drainage blockage or poor drainage, condensation and dripping problems are annoying problems in the air-conditioning system, and the matter is not big or small; Most of the reasons for the frequent drainage blockage and dripping make the HVAC unable to use normally are due to air leakage in the air duct, poor insulation, inadequate insulation of the water pipe valves, etc., which are summarized as follows:
1) The drainage slope is not enough, the pipeline has accumulated water for a long time, the water quality microorganisms and bacteria breed, moss, etc., which are easy to cause blockage, and the solution is to ensure that the drainage slope is above 1%, and regular maintenance is required.
2) If there is a negative pressure cavity in the air conditioning cabinet, a water trap needs to be installed, and the drop of the trap should consider its negative pressure overcoming height.
3) The pipeline insulation is not constructed according to the standard, the material of the pipeline is of inferior quality, there is no timely maintenance, and the water pressure is not tested in time. The thickness of the material is not enough, and the surface temperature of the insulation material reaches the highest temperature during operation and condensation is generated.
Solution: Replace or thicken the insulation cotton.
4) The condensation and dripping of water at the air outlet are mainly due to the low air supply temperature, the ambient temperature is too high or the intersection with the external airflow, reaching the highest temperature, and the condensation appears;
Workaround:1The position of doors and windows near the air outlet should be closed or reduced as much as possible.
2.Consider replacing the material of the air outlet, the metal material is prone to condensation, and can be made of wood and ABS (plastic).
3.If it is a cold water system, the system can properly control the water supply temperature, which can increase the supply air temperature and reduce the possibility of condensation.
4.When designing, the air-conditioning equipment with a small number of high air volume coil rows is used as far as possible, the air supply temperature is higher, and the air-conditioning equipment with 4 rows of pipes has less condensation probability than 6 rows and 8 rows of pipes, and the possibility of condensation of the equipment is also less.
Fifth, the problem of water circulation of air conditioning
In addition to the cooling tower and the amount of water, the main reason for the smooth flow of water circulation is related to the quality of the installed HVAC pipeline and the quality of the water quality, if the pipeline of the water system is not cleaned in time, the poor water quality of the cooling water will seriously damage the equipment, reduce the life of the equipment, and eventually lead to the waste of resources; The air conditioning system is not supplied with water over a long distance, and the refrigeration effect near the pump is good, and the effect is poor at a distance.
Cooling water system.
1) The cooling water tower and cooling water device must be higher than the suction inlet of the cold water pump, and there can be no high arch in the cooling water tower and the water pump, and the water level is higher than the cooling water tower. Try to avoid the low level of the cooling water tower and the high position system of the main engine, which is easy to cause the loss of cooling water and the difficulty of secondary starting.
2) Regularly carry out water treatment testing to keep the water quality good, which is conducive to the heat exchange effect of the host and reduces the operating current. It is more energy-saving and reduces operating costs.
Chilled water system.
1) The area of high-rise and flat floors is too large, which will cause uneven water supply and excessive water pressure difference, so it is recommended to adopt horizontal and vertical same-way pipeline design to maintain the same cooling effect.
2) It is also possible to use dynamic pressure balancing valve, but the investment cost is higher.
Conclusion
To sum up, the design should consider energy conservation and emission reduction, the system is clear, can be used for a long time as the principle, the construction should be honest in the later operation management is simple and convenient maintenance as the goal, the early stage of construction is fully considered, and the development of a detailed construction plan can avoid many problems, according to some of the problem solutions summarized in the actual work, which can be used for your reference.
This article was edited by Zhang Zhixiong, an engineer of KWG Construction (Guangdong).