HVAC Construction Technology and Management: All Key Points to Note Are Here!

Process Flow of Laying Air Conditioning Water Pipe Pipeline:
Pipeline Painting:
When the welded steel pipes and seamless steel pipes are transported to the site, the first step is to carry out surface rust removal treatment. First, use a grinder to polish off the surface rust until the surface is smooth. Prepare the anti-rust paint with the appropriate concentration and evenly apply it twice. Place the pipes in a well-ventilated area. After drying, store them in the warehouse.
Bracket Fabrication:
Use a cutting machine for cutting. Measure the length of the section steel to be cut in advance, place it in the work area, and prepare for welding to fabricate brackets of the required size. Ensure that the cut ends are flush and free of burrs.
Pipe End Fabrication on the Ground:
File the pipe ends flat to make them smooth and free of burrs. Remove all iron filings and oil stains inside the pipes. Carry out pre-processing according to the pipeline connection requirements. Generally, there are three connection methods: threaded connection, welding, and hoop connection.

For pipes that need threading, use a threading plate or a threading machine. Select the die specifications according to the outer diameter. There are two threading methods: manual threading and machine threading. In large projects, machine threading is usually adopted. When the pipe diameter is above DN25, it should be threaded twice. The threads should be regular, not too long, and clear and full.
For pipes that need welding, prepare the bevel according to the pipeline wall thickness. Use a grinder to polish at a 45-degree angle to ensure that the pipe end bevel is even and smooth, meeting the specification requirements.
For pipes that need hoop connection, use a grooving machine. Select the groove depth according to the outer diameter. The pipe ends must be flush, and the groove depth must be clear and full.
Installation of Pipeline Brackets:
Pipeline brackets are generally divided into three types according to the installation position: suspended installation, side installation, and top installation.
For suspended installation of brackets, select appropriate expansion bolts according to the floor and load-bearing requirements. After tightening them with the brackets, ensure that they are stable, safe, and have a certain safety factor.
For side installation of brackets, select appropriate expansion bolts and connection methods according to the load-bearing requirements. For those with low load-bearing requirements, simply select appropriate expansion bolts and tighten them with the brackets. For those with high load-bearing requirements, select an appropriate load-bearing position according to the weight, choose an appropriate area at the connection position and attach a thick steel plate to disperse the stress points, ensuring stability, safety, and a certain safety factor.
For top installation of brackets, select an appropriate bracket form according to the load-bearing requirements, select an appropriate load-bearing position, and tighten it with the bottom surface to ensure that the bracket form and the load-bearing position are safe and stable.
Pipeline Connection and Installation:
Pipeline connections are generally divided into three types according to the connection form: threaded connection, pipeline flange or welding, and hoop connection.
Threaded connection: Wrap hemp yarn around the pipe end and tighten it with the pipe fitting.
Pipeline welding: Align the pipes, select an appropriate welding machine and current, and weld twice. The surface should be smooth and the weld lines should be even.
Hoop connection: Select appropriate hoop fittings, align the pipe ends, and tighten the pipe fittings.
Installation of the External Thermal Insulation Layer of the Air Conditioning Water Pipe:
The thermal insulation material for the air conditioning water pipe is generally rubber and plastic, and the thickness should be in accordance with the design requirements. If rubber and plastic insulation is used, first make the surface of the water pipe clean, and then bond it with special rubber and plastic glue. Apply an additional layer of insulation to the valve. Check the joints to ensure that there is no glue opening.
Selection of the External Protective Layer of the Air Conditioning Water Pipe:
The materials of the external protective layer of the insulation are generally divided into four types: tie straps, thin galvanized steel sheets, aluminum sheets, and stainless steel sheets. For those with general requirements, tie straps are usually used. For outdoor areas or machine rooms with not very high requirements where people often go, thin galvanized steel sheets are used. For areas with high requirements, choose between aluminum sheets and stainless steel sheets according to the environmental conditions and the requirements of the property owner.
Process Flow and Key Points for Attention of Laying Air Conditioning Duct Pipeline:
Pipeline Processing:
The materials of the air conditioning duct generally include galvanized steel sheets, composite glass fiber ducts, phenolic composite ducts, glass fiber reinforced plastic ducts, etc. Here we only talk about the processing of galvanized steel sheet ducts. Cut the galvanized steel sheet according to the design size, use a corner folding machine to fold a right angle, use a special grooving machine to groove the joint, and then tap the corners with a wooden hammer after it is assembled.

When the duct size is relatively large, special reinforcement is required for the duct. Usually, the methods adopted include: processing the steel sheet into convex ribs; longitudinally setting reinforcement ribs on the inner wall of the duct; using angle steel to make a reinforcement frame.
Bracket Fabrication:
Use a cutting machine for cutting. Measure the length of the section steel to be cut in advance, place it in the work area, and prepare for welding to fabricate brackets of the required size. Ensure that the cut ends are flush and free of burrs.
Flange Fabrication:
There are two methods for fabricating the flanges of the galvanized air conditioning ducts according to the different wind pressure and functions of the ducts: worker plate flanges and angle iron flanges.
Worker plate flanges are processed with special machines, which are fast and convenient for installation, but they can bear relatively low wind pressure and are generally used for medium and low-pressure pipelines.
For angle iron flanges, punch a bolt hole every ten centimeters with a punch press and weld them according to the design size. They are generally used for medium and high-pressure pipelines. According to the specification requirements, angle iron flanges are used in the fire protection system.
Installation of Pipeline Brackets:
Pipeline brackets are generally divided into three types according to the installation position: suspended installation, side installation, and top installation.
For suspended installation of brackets, select appropriate expansion bolts according to the floor and load-bearing requirements. After tightening them with the brackets, ensure that they are stable, safe, and have a certain safety factor.
For side installation of the brackets, appropriate expansion bolts and connection methods should be selected according to the load-bearing requirements. For those with low load-bearing requirements, simply select appropriate expansion bolts and tighten them with the brackets. For those with high load-bearing requirements, an appropriate load-bearing position should be selected according to the weight, and a thick steel plate should be attached to an appropriate area at the connection position to disperse the stress points, ensuring stability, safety, and a certain safety factor.
For top installation of the brackets, an appropriate bracket form should be selected according to the load-bearing requirements, an appropriate load-bearing position should be chosen, and it should be tightened with the bottom surface to ensure that the bracket form and the load-bearing position are safe and stable.
Pipeline Connection and Installation:
Pipeline connections are generally divided into three types according to the connection form: pipeline welding, flange connection, and socket connection.
Pipeline welding: The pipeline is directly welded with a welding machine, which is generally used in places with clean grade requirements such as kitchens, laboratories, and hospitals.
Flange welding: Adhere a suitable sealing strip to the pipe end, align the pipe ends, and connect them with bolts or special connectors to ensure that the joint is smooth and airtight.
Socket connection: Select appropriate socket connectors, align the pipe ends, firmly connect the socket connectors with the air duct, and insert the connectors to ensure that the joint is smooth and airtight.
Installation of the External Thermal Insulation Layer of the Air Conditioning Duct:
The air conditioning duct should be insulated as required. The insulation material is generally rubber and plastic or glass wool, and the thickness should be in accordance with the design requirements. If rubber and plastic insulation is used, first make the surface of the air duct clean, and then bond it with special rubber and plastic glue. Apply an additional layer of insulation to the flange. Check the joints, and it is qualified if there is no glue opening or air drum phenomenon. If glass wool insulation is used, first bond the insulation nails. Try to select thicker insulation nails and bond them as required. When placing the insulation board, try to make it penetrate the insulation layer. Bond the joints with aluminum foil adhesive tape, and apply insulation to the flange separately.
Selection of the Protective Layer of the Air Conditioning Duct:
The materials of the external protective layer of the insulation are generally divided into four types: tie straps, thin galvanized steel sheets, aluminum sheets, and stainless steel sheets. For those with general requirements, tie straps are usually used. For outdoor areas or machine rooms with not very high requirements where people often go, thin galvanized steel sheets are used. For areas with high requirements, choose between aluminum sheets and stainless steel sheets according to the environmental conditions and the requirements of the property owner.
Process Flow and Precautions for Equipment Installation:
Model Selection of Fan Coil Units:
Fan coil units are divided into three types according to the wind pressure: ordinary type (wind pressure 12pa), high static pressure type (wind pressure 30pa), and ultra-high static pressure type (wind pressure 50pa).
Fan coil units are divided into two types according to the motor form: DC type and AC type. Generally, AC motors are used.
Fan coil units are divided into two types according to the form of the static pressure box: with a built-in static pressure box and without a static pressure box. Generally, fan coil units without a static pressure box are used.
Fan coil units are divided into two types according to the number of rows of the cooling coils: three-row pipes and two-row pipes. Generally, three-row pipes are used.
Fan coil units are divided into two types according to the form of condensed water drainage: pressure drainage and gravity drainage. Generally, gravity drainage is selected.
Model Selection of Air Handling Units:
Air handling units are divided into three types according to the fresh air: pure fresh air units, hybrid units, and pure indoor air handling units.
Air handling units are divided into preheating section, heating section, refrigeration section, and humidifying section according to their functions.
Air handling units are divided into variable frequency DC motors and AC motors according to the motor type.
Air handling units are divided into 220V or 380V according to the voltage.
Air handling units are divided into primary efficiency, medium efficiency, and high efficiency according to the filtration grade.
Model Selection of Fresh Air and Exhaust Air Fans:
Fresh air and exhaust air fans are divided into axial fans and turbine fans according to the blade form.
Fresh air and exhaust air fans are divided into fire-fighting fans and ordinary fans according to the fire protection requirements.
Fresh air and exhaust air fans are divided into box-shaped fans and circular fans according to their shapes.
Model Selection of Water Pumps:
Water pumps are divided into vertical type and horizontal type according to the installation form.
Water pumps are divided into circulating water pumps, pressure stabilizing water pumps, and water supply pumps according to their functions.
Water pumps are divided into DC motors and AC motors according to the motor type.
Model Selection of Heat Exchangers:
Heat exchangers are divided into two forms: volume heat exchangers and plate heat exchangers.
Volume heat exchangers are generally used in hot water supply systems. The heat exchange power is relatively small, with one side having relatively high pressure and the other side having relatively low pressure.
Plate heat exchangers are generally used in air conditioning, heating, and other systems. The heat exchange power is relatively large, and the pressure on both sides is relatively high.
Model Selection of Refrigeration Units:
Refrigeration units are divided into centrifugal type, screw type, and turbine type according to the refrigerant compression form. Generally, turbine type is used for small units, screw type for medium-sized units, and centrifugal type for large units.
Refrigeration units are divided into air-cooled and water-cooled according to the cooling and heating sources.
Refrigeration units are divided into R22, R410a, etc. according to the refrigerant.
During the installation process of the refrigeration monomer, when conducting the strength test and tightness test, if the following conditions are met, only the tightness test can be carried out without conducting the strength test.
① The manufacturer has already carried out the strength test and has a certificate of conformity;
② There is no damage or rust phenomenon;
③ Within the time limit specified in the technical documents.
Installation of Fan Coil Units:
Fan coil units are divided into concealed installation and exposed installation according to the installation form.
For fan coil units that need to be installed concealed, they are generally installed in the suspended ceiling and hoisted directly with through-threaded rods. Pay attention to the slope direction of the condensed water.
For fan coil units that need to be installed exposed, equipment brackets are generally required to be made to be as aesthetically pleasing as possible, and pay attention to the connection position and direction.
Symbol Explanation: 1 - Flexible connection; 2 - Electric two-way valve; 3 - Globe valve; 4 - Y-type filter; 5 - Suspension rod; 6 - Fan coil unit; 7 - Flexible connection of the air duct; 8 - Condensate drainage.
Installation of Air Handling Units:
Air handling units are divided into floor-mounted installation and suspended installation.
For suspended air handling units, suspended shock absorbers should be added, and appropriate brackets and expansion bolts can be selected.
Floor-mounted air handling units generally require a concrete foundation. Small units come with built-in shock absorption, and adding shock absorption pads is sufficient. Large air handling units require floor-mounted shock absorbers.
Installation of Fresh Air and Exhaust Air Fans:
The installation of fresh air and exhaust air fans is divided into suspended installation and floor-mounted installation.
For suspended fresh air and exhaust air fans, suspended shock absorbers should be added, and appropriate brackets and expansion bolts can be selected.
Floor-mounted fresh air and exhaust air fans generally also require a concrete foundation. Small units come with built-in shock absorption, and adding shock absorption pads is sufficient. Large air handling units require floor-mounted shock absorbers.
Installation of Water Pumps:
The installation of water pumps mainly involves the installation of the base. For small water pumps, a base is made of channel steel, and it is fixed with shock absorption pads. For large water pumps, floor-mounted shock absorption is required. A concrete block is made on top of the shock absorber, and the water pump is fixed on the concrete block.
Installation of Heat Exchangers:
The main difficulty in the installation of heat exchangers is the transportation problem of the equipment. The volume of the volume heat exchanger is particularly large, so the transportation channels and equipment should be prepared in advance. The plate heat exchanger has a small volume but a considerable weight. After ensuring a proper bracket is made, appropriate equipment and tools should be selected.
Installation of Refrigeration Units:
The installation of refrigeration units mainly depends on whether the cooling source of the equipment is air-cooled or water-cooled.
Air-cooled units are all installed outdoors. After completing the civil engineering foundation and base, they can be transported to the designated position and fixed using large cranes and transportation equipment.
Water-cooled units are generally installed on the indoor ground floor. The reservation of the transportation channel and the selection of the transportation equipment are the key points.
Process Flow and Key Points for Attention of System Debugging:
Pressure Test of the Air Conditioning Water Pipeline:
The chilled water, hot water, and cooling water systems of the air conditioning pipeline belong to a closed system and operate under a certain pressure. When the working pressure is less than or equal to 1.0MPa, the test pressure is 1.5 times the working pressure, but not less than 0.6MPa at the minimum; when the working pressure is greater than 1.0MPa, the test pressure is the working pressure plus 0.5MPa. After maintaining the pressure for 24 hours without seepage or leakage, it is considered qualified.
The air conditioning condensate pipeline should undergo a full water test. After being filled with water for 24 hours, check that there is no seepage, no leakage, smooth drainage, and no reverse slope. If so, it is considered qualified.
Light Leakage Test of the Air Conditioning Air Duct:
According to the different wind pressures and uses of the air conditioning air duct, spot checks are carried out for inspection according to the requirements of the code. Generally, 20% of the ducts are randomly inspected. It is considered qualified if there is no air leakage and no light leakage points.
The light leakage detection is to choose a pitch-black night, turn off all the lights, shine an incandescent lamp inside the pipeline, and check the light leakage situation outside.
Equipment Commissioning:
After all the installation work is completed, check whether all the circuits are normal, whether the water pipeline valves are opened and closed as required, and whether all the air duct valves are in the required state. After all the work is normal, start the equipment and observe whether it is operating normally. If not, check the cause, make corrections, and then test the machine again until it operates normally.
Air Conditioning Water Balance Debugging:
After the construction of the air conditioning water system is completed and the operation is stable, communicate with the design party, calculate the valve flow rates at all points, use a special instrument to test the ratio of the actual flow rate of the entire main system to the theoretical value, calculate the actual flow rates of the valve points uniformly according to the proportion, and adjust the opening degree of each valve uniformly according to the achievable actual requirements until the actual value is reached, and the debugging is completed.
Air Conditioning Air Balance Debugging:
After the construction of the air conditioning air system is completed and the equipment operation is stable, communicate with the design party, calculate the air volume of the air valves at all points, use a special instrument to test the ratio of the actual air volume of the entire unit to the theoretical value, calculate the actual flow rates of the air valves uniformly according to the proportion, and adjust the opening degree of each valve uniformly according to the achievable actual requirements until the actual value is reached, and the debugging is completed.
Debugging of Building Intelligent Control:
After all the above work is completed and the weak current, strong current, HVAC, and water supply systems are normal, start each unit in the control room using the weak current system, test the opening status of the valves that require electricity, test the equipment. If there are any problems, check the cause, repair it immediately. After everything is normal, the debugging is completed.
Matters Ne Management:
1. First, make a good record of the drawingeding Attention in review, be familiar with the drawings of this professional field, and go to the site to check whether the construction is carried out in accordance with the drawings.
2. When inspecting, be familiar with the construction specifications and construction process standards of this professional field.
3. Control the materials, check the inventory records of the construction unit for incoming and outgoing materials, and strictly prevent the phenomenon of material waste.
4. Manage the civilized construction on site, and require the construction unit to clean up the site, use up the materials, and keep the site tidy after the work is completed.
5. Timely convey the changes proposed by the Party A to the following construction units to avoid unnecessary rework, and make good visa records.