With the era of rapid social and economic development, China’s comprehensive strength continues to improve, and the overall living standards of the people have risen. Consequently, there are higher demands for residential environments. HVAC (Heating, Ventilation, and Air Conditioning) systems can further enhance the overall comfort of living spaces and are widely welcomed in society. To maximize the effectiveness of HVAC systems, technicians must strictly control every installation phase and adhere to relevant operational standards during the installation process. At the same time, construction companies should continuously improve installation techniques in line with technological advancements in HVAC systems, ensuring the overall quality of system installations and providing greater assurance for people’s comfortable living.

Keywords: HVAC, ductwork, radiators, installation

1. Overview of HVAC Systems

Installing HVAC systems in modern buildings can effectively maintain a constant temperature and humidity indoors, while also providing ventilation, heating, and other comprehensive effects. This significantly improves indoor air quality, benefiting the health of residents. Traditional air conditioning systems primarily regulate indoor temperatures but do not improve air quality. In contrast, HVAC systems are more intelligent and can enhance the comfort of the entire living environment. However, the installation process and technical requirements for HVAC systems are higher than those for traditional air conditioning systems. Therefore, it is crucial to strengthen quality control during the installation process to effectively avoid issues that could affect the air regulation functions of HVAC systems. Currently, HVAC construction has become a top priority in building installations, and due to the complexity of the installation steps, it can impact subsequent usage. Thus, the installation process must be rigorously inspected to avoid any loopholes. The design of HVAC installations mainly includes three aspects: the air conditioning water system, fresh air system, and exhaust system. Any oversights during the installation process could affect the performance of the air conditioning system, making it essential to strictly control the construction process to ensure the quality of HVAC installations and achieve the desired results.

2. Case Study

2.1 Overview

This article takes Building No. 2 of Beixian Pavilion in Xicheng District (now known as Guang’an Hotel) as an example. Building No. 2 of Beixian Pavilion was invested and constructed by Beijing Haicheng Investment Co., Ltd. It is located at the northeast corner of Guang’anmen Bridge, and has six floors above ground and two underground, with a total construction area of 13,000 m². Floors 2 to 5 contain guest rooms, totaling 152 suites. The HVAC system for this project employs a traditional fan coil plus fresh air approach, with one horizontal fan coil installed in each room for indoor temperature regulation. Each floor is equipped with one fresh air unit that delivers compliant fresh air to each room via metal ducts, adjusting indoor air humidity and cleanliness.The fan coils use a two-pipe system, supplying chilled water in summer and hot water in winter. The chilled water temperature ranges from 5 to 12°C, provided by two screw chillers in the refrigeration room. The hot water temperature is between 50 and 60°C, supplied by two plate heat exchangers in the heat exchange station. The heat source is provided by municipal heating. Both the refrigeration room and the heat exchange station are located on the first underground floor. The refrigeration room is also equipped with two chilled water circulation pumps, two cooling water circulation pumps, and two makeup water pumps. The heat exchange station includes two heating circulation pumps, two makeup water pumps, and softened water tanks. Cooling towers are installed on the roof. The piping materials for the HVAC water system are as follows: for cold and hot water pipes with a diameter of DN≤40, hot-dip galvanized steel pipes with threaded connections are used; for DN>40, welded steel pipes with welded connections are used. Cooling water pipes are made of welded steel, while condensate pipes use hot-dip galvanized steel with threaded connections. The basement is equipped with a mechanical supply exhaust ventilation and smoke extraction systems. Mechanical supply and exhaust ventilation are also installed in the elevator machine room, transformer room, pump room, and heat exchange station.

2.2 Installation of Fan Coils

Process Flow: Preparation → Unpacking Inspection → Motor Check and Trial Run → Water Pressure Test of the Coils → Bracket Installation → Secure Fan Coil Installation → Piping Connection → Control Panel Installation → Inspection.

Installation Preparation: After the fan coils arrive on-site, they should be properly stored. Installation should occur as they are transported, ensuring product protection during concurrent work with other trades to prevent damage. During civil construction, proper coordination is essential, with holes reserved according to design locations. Once civil work is complete, the installation dimensions should be checked against design requirements. Fan coils should be installed as they are transported, with care taken to protect finished products during overlapping work.

Equipment Unpacking Inspection: Each motor casing and surface heat exchanger should be inspected for damage, corrosion, or defects. The fan coil and induced draft fan should include packing lists, equipment manuals, quality certificates, and performance testing reports. Imported equipment must also have inspection certificates. The structural form, installation method, outlet direction, and inlet position of the fan coil and induced draft fan must meet design installation requirements. The main materials and auxiliary materials used for equipment installation should comply with design specifications and possess factory quality certificates.

Individual Pressure Testing and Three-Speed Trial Operation of Equipment: Equipment should be tested in coordination with electrical professionals for three-speed operation. The fan coil should undergo a water pressure test at 1.5 times the working pressure, with no leaks within 2 minutes deemed acceptable.

Bracket Installation: Horizontal fan coils and induced draft fans should have independent support and hanging brackets. Their installation height and position must be correct and securely fixed. The hanging rods should not sway and should allow for easy disassembly and maintenance. The hanging rods and trays should be secured with double nuts, and leveled, and the condensate tray should have a slight slope toward the condensate pipe. Effective and reliable vibration reduction measures should be taken where required.

Secure Installation of the Unit: The installation should be straight, firm, and correctly positioned. Concealed horizontal fan coils and induced draft fans should have accessible inspection doors in the ceiling for easy disassembly and maintenance.

Piping Connection: The connection between ducts, return air boxes, and fan coil fans should be tight and secure.

Inspection: After installation, equipment and piping should be inspected. The fan coil must be stable, with a reasonable slope, and all instruments and valve components installed correctly. The condensate drainage pipes (troughs) should be unobstructed, with no air leaks, water seepage, or condensate drainage issues. After installation, the fan coil should be cleaned, ensuring no debris remains inside the unit.

Quality Standards: Each fan coil should undergo individual three-speed trial operation and water pressure testing before installation. The mechanical components must not rub against each other, and electrical components must be free from leakage. Each fan coil should pass a water pressure test at 1.5 times the working pressure, with no leaks within 2 minutes deemed acceptable. The unit should have independent support and hanging brackets, with the correct installation position, height, and slope, and the connection to ducts, return air boxes, or outlets must be tight and reliable.

2.3 Installation of Air Conditioning Water Pipes

Piping Installation Process: Construction Preparation → Pipe Anti-Corrosion → Prefabrication → Support and Bracket Installation → Pipe Installation → Pipe Water Testing → Pipe Anti-Corrosion and Insulation → Pipe Testing → Acceptance.

Construction Preparation: Familiarize yourself with the drawings, understand the design intent and requirements, and clarify the process flow, construction procedures, and technical quality requirements. Refer to relevant professional equipment diagrams and architectural drawings to comprehensively arrange various pipelines, checking for coordinate and elevation intersections. Verify that all reserved openings and embedded sleeves are correctly sized and positioned, with any necessary adjustments confirmed by relevant professionals. Before valve installation, check the model and specifications against design requirements and ensure proper cleaning. Both the inner and outer walls of the pipes and fittings should be free from rust and contaminants. After cleaning, the pipe ends should be sealed and kept dry. Any required anti-corrosion treatments should be conducted without omissions. Prefabricated support and hanging brackets according to design specifications. For insulated pipes, use treated wooden pads to separate contact points with the pipes, ensuring the thickness is not less than that of the insulation layer.

Prefabrication: Draw sketches of the piping routes, pipe diameters, transitions, reserved openings, and valve locations based on design drawings. Mark the actual installation positions on-site, measuring accurate dimensions for installation and recording them on the construction sketches. Cut the pipes according to the measurements, using specialized tools for vertical cuts, ensuring smooth edges without burrs. Clean the connecting parts of the pipes and fittings to avoid damage from sand or dust. The pipe connection form should comply with design requirements.

Support and Bracket Installation: The placement of supports and brackets needs to be controlled for stability, ensuring tight connections with the pipes. The connection points of pipelines and equipment should have independent supports and brackets. For the main and branch pipes of the chilled (hot) water and cooling water systems, supporting measures should be used to prevent shaking, and pipes connected to equipment should have vibration-dampening functions. If a single rod support is used for horizontal branch pipes, supporting measures should be provided at the starting point, valve locations, tees, and bends, spaced every 15 meters. For pipes without thermal displacement, the hanging rods should maintain a 90° angle; for pipes with thermal displacement, they should be slightly offset in the direction opposite to thermal expansion, with the degree of offset determined by calculations. The sliding supports should be kept clean, and the installation location should move 1/2 of the displacement value from the center of the support surface. Vertical pipe installations in shafts should have supports spaced every 2-3 floors. The spacing of supports and brackets for horizontal metal pipes should meet acceptance standards, and when installing hot water pipes, the spacing should be widened as required.

2.4 Piping Installation

2.4.1 Piping Installation Deployment

For the air conditioning water system, install the main pipes first, followed by vertical pipes, branch pipes, and accessories, and finally connect to the fan coils.

2.4.2 Connection Process for Hot-Dip Galvanized Steel Pipes

Threading: For cut pipes, thread according to pipe diameter, generally two threads for diameters 15-32 mm, three threads for diameters 40-50 mm, and three to four threads for diameters over 70 mm. For threading machines, clamp the pipe in the threading machine chuck, leaving an appropriate length, and tighten the chuck. Align with the threading gauge, adjust the position according to the required scale; secure the fixed plate and align the lubricant pipe with the threaded end. Start the machine to push the plate, and when the threads reach the appropriate length, gently release the fixed plate. For manual threading, adjust the fixed plate to loosen it, set the threading plate to 0°, and according to the numbered sequence, set the thread cutter to precisely align with the relevant scale. Secure the fixed plate, place the pipe in the pressure clamp, reserving the required length, and tighten it. Gently lower the threading plate onto the pipe while adjusting the tightness, using both hands to push the threading plate to create 2-3 threads, then flip the threading plate to the side. When the threads are completed, slowly release the fixed plate, start the machine, and retract the plate, ensuring proper thread tapering.

2.4.3 Fitting Installation

Based on the site-measured sketches, fit the threaded pipes with fittings. During the fitting installation process, ensure that the required fittings are threaded, adjusting the tightness. Apply lead oil and wrap it with hemp (or Teflon tape) before inserting the fittings, using a pipe wrench to tighten them securely, leaving 2-3 threads exposed. Remove any filling materials and clean off the lead oil. Select appropriate pipe wrenches based on the specifications of the installed fittings.

2.4.4 Straightening Pipe Segments

Before installation, straightening of the already installed fittings is necessary. Apply lead oil to the threaded sections of the connected pipe segments. When connecting two or more segments, in addition to considering the position of reserved openings, pay attention to the straightness of the pipes. After adjustments, ensure the reserved openings are positioned reasonably and straight. Before straightening, verify the pipe diameters, reserved openings, and transitions against the design drawings. The straightening work should ensure the pipes are level, using a pipe adjustment rack or platform. Typically, two people should work together, one at one end of the segment to visually check the level, and the other at the bend using a hammer to adjust. While striking, observe the straightness of the pipe segment, marking the connection points after straightening. Once detached, connect the next segment until all segments are adjusted. When straightening segments with installed valves, first remove the valve cover, ensuring the valve is secured before striking to prevent damage to the valve body. During straightening, avoid damaging the pipes and fittings, and do not use heating methods for straightening galvanized carbon steel pipes or steel-plastic composite pipes.

3. Improvement and Optimization of HVAC System Installation Techniques

3.1 Optimizing Pipeline Installation Techniques

Before implementation, a representative sample location must be selected and thoroughly understood to identify key difficulties in the operation and propose corresponding solutions. Summarize potential hazards and determine relevant countermeasures, creating targeted operational plans to ensure smooth pipeline installation. Design parameter calculations, specifications, and operational drawings are the main references for the installation phase, making the accuracy of design content fundamental to ensuring correct implementation. Conducting preliminary site surveys to assess actual working conditions comprehensively allows for optimized design depth and proper pipeline layout. Coordination among various departments is key to enhancing pipeline installation efforts.

3.2 Controlling Noise Issues

In recent years, the noise generated by HVAC equipment has increasingly affected people’s lives and work. Therefore, noise reduction measures are typically implemented during equipment installation. First, a noise control work plan should be developed. When installing fan coils, vibration pads should be used to reduce operational noise. When connecting chilled and hot water to fan coils, corrugated pipes should be installed on the supply and return water branches to isolate noise and prevent propagation through the pipes. Additionally, sound-absorbing devices should be installed at detailed locations to ensure effective noise treatment during the operational phase. When selecting equipment, prioritize ultra-low noise fan coils and install canvas flexible connections at the junctions between fan coils and ducts to mitigate operational noise. Prior to implementation, relevant personnel should receive technical training to ensure they understand the related technical measures, adhering to national standards and technical specifications for pipe work.

3.3 Improving Construction Techniques and Enhancing Technical Proficiency

First, enhance the design plan. Before design work, conduct thorough site surveys to assess evaluation needs, comparing technical and economic aspects of each plan to find the best design content. Second, enhance functionality. Optimizing HVAC functions is a crucial step in energy conservation and environmental protection efforts, such as improving insulation materials for exterior walls. Third, enhance product selection. Based on implementation standards and relevant design content, choose products reasonably to ensure effective implementation and meet user needs, ultimately enhancing the application of talent.

Ensure your HVAC systems deliver optimal performance and comfort with professional installation and HVAC testing services. Contact Kingda today to discuss how we can help you meet quality standards and enhance your products’ market appeal!